WO2020035607A1

WO2020035607A1 - Novel catalytic materials

Info

Publication number: WO2020035607A1
Application number: PCT/EP2019/072050
Authority: WO
Inventors: Nadežda KONGI; Kaido TAMMEVESKI; Pavel STARKOV; Kefeng PING
Original assignee: University Of Tartu; Tallinn University Of Technology
Priority date: 2018-08-17
Filing date: 2019-08-16
Publication date: 2020-02-20
Also published as: GB201813439D0; EP3837732A1

Abstract

The present invention relates to novel catalysts, methods of making said catalysts, associated chemical intermediates and uses of said catalysts.

Description

Novel Catalytic Materials

Technical field

Background to the invention

Proton exchange membrane fuel cells (PEMFCs) address both alternative energy demands and sustainability by virtually converting dihydrogen and dioxygen into water (Wang, 201 1 ; Debe, 2012; Katsounaros, 2014; Shao, 2016). Electrode materials for such devices have to be cost- effective in order to drive the technology into the marketplace. While carbon supported platinum- group metal catalysts remain the state-of-the-art approach (Gasteiger, 2003), in particular 0.4 mgPt cm^-2, the cost of precious metals (e.g. platinum, palladium, iridium and gold) means alternatives are highly sought after.

One potential approach is the use of non-noble metal and nitrogen-doped carbon-based systems, in particular Fe/N/C-type (Wu, 201 1 ). Such systems exhibit excellent electrocatalytic activity towards the oxygen reduction reaction (ORR), while being highly durable and immune to methanol and CO poisoning (Li, 2010; Xia, 2016). Typically, these electrocatalysts are prepared in a‘top- down’ approach from a carbon rich starting material (e.g. carbon nanotubes (CNTs), graphene, carbide-derived carbon, and the like) using carbonisation/pyrolysis by (often, repetitively) doping the precursors with various metals and heteroatom-sources (Masa, 2015; Ratso, 2018).

Early examples of non-platinum-group catalytic materials for ORR were based on metal phthalocyanines (Jasinski, 1964), however, they were not sufficiently active or stable in either acidic or alkaline media, and decomposed on pyrolysis. The sites in metal-nitrogen-carbon (M/N/C) based catalytic materials which are particularly responsible for ORR activity are still under debate (Sarapuu, 2018). It was suggested that high electrocatalytic activity is attributed to MN_X sites e.g. FeN_x, CoN_x (Kim, 2017), however, it remains unclear whether the metal ion participates as an active site or it only facilitates the formation of active sites responsible for high electrocatalytic behaviour towards the ORR. In recent years, several mechanistic studies have also introduced the possibility of ligand-centred molecular pathways (Guo, 2016; Yang, 2016; Miner, 2017; Dey, 2018):

A promising alternative to top-down approaches to prepare ORR catalysts is the use of metal- organic frameworks (typically, 3D MOFs), which deliver both the required metal centres and the organic constituents (Wang, 2016; Wu, 2017; Liao, 2018). Typically, MOFs form standalone crystals, which are based on imidazolates or carboxylate precursors, with only a few examples of polycatechols and related systems (i.e. the sulphur and nitrogen analogues) known to date (Cote, 2005; Spitler, 2010; Fei, 2014; Miner 2016). For energy conversion and storage purposes, both carbonisation and nitrogen-doping of MOFs are almost always required to achieve good performance (Wang, 2016; Liao, 2018). In addition to 3D MOFs, two- and three-dimensional porous materials such as covalent organic frameworks (COFs) and 2D metal-organic frameworks (2D MOF) are other alternatives to precious metal catalysts (Colson 2013; Cooper, 2017; Das, 2017). However, the chemistry of these materials received limited attention, with only one work on carbonisation- and dopant-free use of nickel-based 2D MOF Ni3(HITP)2 reported to date (Miner, 2016).

International patent application W0201401 1831 discloses the use of carbendazim (CBDZ) in the manufacture of catalytic material.

carbendazim

A 2D MOF derived from 1 /-/-benzimidazole-5, 6-dicarboxylic acid and manganese ions has been described. However, the catalytic properties of this framework were not investigated (Zhang, 2016).

1 /-/-benzimidazole-5, 6-dicarboxylic acid

International patent applications W002088148, W003064030, W02004101575 and

W02007038508 disclose porous MOFs said to be of use in fields such as gas storage.

Although several catechol-incorporating MOFs (Hmadeh, 2012; Nguyen, 2015) and COFs (Cote, 2005; Spitler, 2010; Ding, 201 1 ) as well as MOFs that are post-synthetically modified to introduce catechol moieties (Fei, 2014) were previously reported, such catechol-based systems rely on the use of either trigonal hexahydroxytriphenylene and quadrilateral octahydroxyphthalocyanine precursors or post-synthetic introduction or unmasking of catechol units.

In regard to chemical catalysis, the metal-based catalyst systems are based on either 1 ) homogenous metal-ligand complexes, which are either pre-made or pre-formed in situ by mixing a metal source and a ligand, or 2) heterogeneous including nanoparticles, nanoclusters, etc. In addition, several MOF-based catalytic materials have been described (Zhu, 2017; Chen, 2018). Upon carbonisation, the chemical nature of the metal-organic linker pairs in pre-formed MOFs can be altered to enhance or alter catalytic properties of the catalytic material. Additionally, the physical properties of the catalytic material may improve (decrease in metal-leaching, induction of magnetic properties leading to ease of catalyst recuperation and recycling).

There remains a need for alternative catalysts which are cost-effective and demonstrate an attractive profile. Such catalysts may have one or more benefits relative to known catalysts, such as cost, stability, durability, catalytic properties (including for example, onset potential or half- wave potential), ease of manufacture, ease of use, ease of separation, be non-leaching and the like.

Summary of the invention

The present invention provides a method for forming a catalytic precursor, said method comprising the step of reacting a metal precursor with a benzoimidazolediol-type linker. Also provided is a method for forming a catalytic material, said method comprising the carbonisation of a catalyst precursor obtainable by reacting a metal precursor with a

benzoimidazolediol-type linker.

Additionally provided is a method for forming a catalytic material, said method comprising the steps:

(a) reacting a metal precursor with a benzoimidazolediol-type linker to form a catalyst precursor;

(b) carbonisation of the catalyst precursor.

Further is provided a catalytic precursor and catalytic material as described herein, together with the use of catalytic material as described herein as a catalyst. Electrodes comprising said catalytic material and fuel cells comprising said electrodes are also provided by the present invention. Solutions suitable for the preparation of said catalytic precursors, uses of said catalytic precursors and catalytic materials and are also provided.

Description of the figures

Figure 1 Diagrammatic representation of Fe(lll) 1 /-/-benzo[c/]imidazole-5,6-diol derived catalytic material TAL-001 C@800 according to Example 2.

Figure 2 X-ray diffraction pattern of Fe(lll) 1 /-/-benzo[c/]imidazole-5,6-diol-based catalyst precursor TAL-001 , TAL-002, TAL-004, TAL-005.

Figure 3a-d Characterization of TAL-001 catalyst precursor material - a, XPS survey

spectrum, inset: core-level spectrum in Fe2p region; b, XPS core level spectrum in the N1 s region; c and d, SEM images at different magnifications.

Figure 4a-d Characterization of TAL-001 C@800 catalytic material - a, XPS survey spectrum, inset: core-level spectrum in Fe2p region; b, XPS core level spectrum in the N1 s region; c and d, SEM images at different magnifications.

Figure 5 TEM images of TAL-001 C@800 catalytic material at different magnifications. Figure 6a-e Electrochemical characterisation of TAL-001 C@800 catalytic material.

Figure 7a-f Electrochemical characterisation of Fe(lll) and 1 /-/-benzo[c/]imidazole-5,6-diol derived catalysts prepare at various carbonisation temperatures (TAL- 001 C@800, TAL-001 C@900 and TAL-001 C@1000) and with acid leaching (TAL-001 C@900L); insets: electron counts.

Figure 8 Scanning electron micrographs at different magnifications of various metal

catalyst precursor (TAL-002, TAL-003, TAL-004, TAL-005, TAL-006 and TAL- 007) and catalytic materials TAL-002C@800, TAL-003C@800, TAL-004C@800 TAL-005C@800, TAL-006C@800 and TAL-007C@800.

Figure 9 Electrochemical characterisation of various metal catalytic materials.

Figure 10 Electrochemical comparison of 1 /-/-benzo[c/]imidazole-5,6-diol, 1 H- benzo[c/]imidazole-5,6-dicarboxylic acid and 5,6-dimethoxy-1 /-/-benzo[c/]imidazole derived catalysts TAL-006C@800 and TAL-007C@800.

Figure 1 1 a-c Characterization of TAL-001 C@900L, TAL-006C@900L and TAL-007C@900L - a, TEM images; b, XRD patterns; c, XPS core level spectrum in the N1 s region. Figure 12a-j Electrochemical characterisation of TAL-001 C@900L and TAL-002C@900L in alkaline and acidic conditions.

Figure 13a-e Electrochemical characterisation of iron and cobalt catalytic materials containing different linkers.

Figure 14a-b Electrochemical characterisation of bimetallic catalytic materials.

Detailed description of the invention

The present invention provides a method for forming a catalytic precursor, said method comprising the step of reacting a metal precursor with a benzoimidazolediol-type linker.

Also provided is a method for forming a catalytic material, said method comprising the carbonisation of a catalyst precursor obtainable by reacting a metal precursor with a benzoimidazolediol-type linker.

(b) carbonisation of the catalyst precursor.

Further is provided a catalytic precursor and catalytic material as described herein, together with the use of catalytic material as described herein as a catalyst. Solutions suitable for the preparation of said catalytic precursors, uses of said catalytic precursors and catalytic materials are also provided.

Benzoimidazolediol-type linker

By the term‘benzoimidazolediol-type linker’ as used herein is meant a compound of formula (I):

wherein

Wi and W₂ are each independently selected from OH, NH2, SH, COOH, B(OH)2, Si(OH)₃, CN, CºCH, CONH2, OCH₃, Ci-₆alkyl and halo;

X is selected from NH, O and S;

Zi and Z2 are each independently H or may be any substituent which allows the compound to retain ability to form a catalyst precursor and catalytic material; and Y is selected from CH or a group which allows the compound to retain ability to form a catalyst precursor and catalytic material;

or a salt thereof.

The invention also provides a compound of formula (I):

wherein

Wi and W2 are each independently selected from OH, NH2, SH, COOH, B(OH)2,

Si(OH)₃, CN, CºCH, CONH2, OCHs, Ci_-6alkyl and halo;

X is selected from NH, O and S;

with the proviso that the compound is not 1 /-/-benzimidazole-5, 6-dicarboxylic acid; or a salt thereof. The invention also provides a compound of formula (I):

wherein

Wi and W₂ are each independently selected from OH, NH2, SH, COOH, B(OH)2, Si(OH)₃, CN, CºCH and CONH₂;

X is selected from NH, O and S;

or a salt thereof.

The invention also provides a compound of formula (I):

wherein

Wi and W2 are each independently selected from OH, NH2, SH, COOH, B(OH)2,

Si(OH)₃, CN, CºCH and CONH₂;

X is selected from NH, O and S;

with the proviso that the compound is not 1 /-/-benzimidazole-5, 6-dicarboxylic acid; or a salt thereof. In one embodiment Wi is OH. In a second embodiment Wi is NH2. In a third embodiment Wi is SH. In a fourth embodiment Wi is COOH. In a fifth embodiment Wi is B(OH)2_. In a sixth embodiment Wi is Si(OH)₃. In a seventh embodiment Wi is CN_. In an eighth embodiment Wi is C=CH_. In a ninth embodiment Wi is CONH₂. In a tenth embodiment Wi is halo, such as F. In an eleventh embodiment, Wi is OCH₃. In a twelfth embodiment, Wi is Ci-6alkyl, such as CH₃.

In one embodiment W₂ is OH. In a second embodiment W₂ is NH₂. In a third embodiment W₂ is SH. In a fourth embodiment W₂ is COOH. In a fifth embodiment W₂ is B(OH)_2. In a sixth embodiment W₂ is Si(OH)₃. In a seventh embodiment W₂ is CN_. In an eighth embodiment W₂ is CºCH_. In a ninth embodiment W₂ is CONH₂. In a tenth embodiment W₂ is halo, such as F. In an eleventh embodiment, W₂ is OCH₃. In a twelfth embodiment, W₂ is Ci-6alkyl, such as CH₃.

In one embodiment Wi and W₂ are the same. In a second embodiment Wi and W₂ are different.

Suitably, Wi is selected from the group consisting of OH, COOH, CH₃ OCH₃, NH₂ and F. Suitably, W₂ is selected from the group consisting of OH, COOH, CH₃ OCH₃, NH₂ and F. Suitably, Wi and W₂ are OH or COOH, especially OH.

Suitably, at least one of Wi and W₂ is F. Suitably, at least one of Wi and W₂ is F and the other is OH. Suitably, Wi is F and W₂ is OH.

Suitably, at least one of Wi and W₂ is NH₂. Suitably, Wi and W₂ are NH₂.

Suitably, at least one of Wi and W₂ is OCH₃. Suitably, Wi and W₂ are OCH₃.

Suitably, at least one of Wi and W₂ is CH₃. Suitably, Wi and W₂ are CH₃.

When Wi or W₂ represent halo, the halo may independently be fluoro, bromo, chloro or iodo.

In one embodiment X is NH. In a second embodiment X is O. In a third embodiment X is S.

Zi is suitably H. Z₁ substituents which may allow the compound to retain ability to form a catalyst precursor and catalytic material include optionally substituted Ci-6alkyl (e.g. Ci-6alkyl), such as optionally substituted Ci-₄alkyl (e.g. Ci-₄alkyl), in particular methyl or ethyl, especially methyl. Z₁ may be optionally substituted phenyl (e.g. phenyl). Z₁ may be halo, such as fluoro, chloro or bromo. Z₁ may be NR^xR^y. 2.₂ is suitably H. Z₂ substituents which may allow the compound to retain ability to form a catalyst precursor and catalytic material include optionally substituted Ci-₆alkyl (e.g. Ci-₆alkyl), such as optionally substituted Ci-₄alkyl (e.g. Ci-₄alkyl), in particular methyl or ethyl, especially methyl. Z₂ may be optionally substituted phenyl (e.g. phenyl). Z₂ may be halo, such as fluoro, chloro or bromo. Z₂ may be NR^xR^y.

In one embodiment Zi and Z₂ are the same. In a second embodiment Zi and Z₂ are different.

Y is suitably CH. A Y groups allows the compound to retain ability to form a catalyst precursor and catalytic material may be CR¹. Y groups which may allow the compound to retain ability to form a catalyst precursor and catalytic material may include BH and BR¹. Other Y groups which may allow the compound to retain ability to form a catalyst precursor and catalytic material may include SiH₂, SiHR¹ and Si(R¹)₂.

Each R¹ is independently selected from an optionally substituted Ci-₆alkyl (e.g. Ci-₆alkyl), an optionally substituted C₃-i₂carbocyclyl (e.g. C₃-i₂carbocyclyl, such as C₃-i₂cycloalkyl), an optionally substituted C₃-i₂heterocarbocyclyl (e.g. C₃-i₂heterocarbocyclyl, such as C₃- i₂cheterocycloalkyl), an optionally substituted C₆-i₂aryl (e.g. C₆-i₂aryl), an optionally substituted C₅-i₂heteroaryl (e.g. C₅-i₂heteroaryl), (CH₂)_nC₃-i₂carbocyclyl which C₃-i₂carbocyclyl group may be optionally substituted (e.g. (CH₂)_nC₃-i₂carbocyclyl, such as (CH₂)_nC₃-i₂cycloalkyl), (CH₂)_nC₃- i₂heterocarbocyclyl which C₃-i₂heterocarbocyclyl group may be optionally substituted (e.g.

(CH₂)_nC₃-i₂heterocarbocyclyl, such as (CH₂)_nC₃-i₂heterocycloalkyl), (CH₂)_nC₆-i₂aryl which Ce- i₂aryl group may be optionally substituted (e.g. (CH₂)_nC₆-i₂aryl), (CH₂)_nC₅-i₂heteroaryl which C₅- i₂heteroaryl group may be optionally substituted (e.g. (CH₂)_nC₃-i₂heteroaryl), C(0)R^x, OR^x, COOR^x, SR^X, C(0)NR^xR^y, NR^xR^y, NHC(0)R^x, NHC(0)0R^x, Ci-₆haloalkyl, (CH₂)_nC(0)R^x,

(CH₂)_nOR^x, (CH₂)_nC(0)0R^x, (CH₂)_nC(0)NR^xR^y, (CH₂)_nNR^xR^y, (CH₂)_nNHC(0)R^x or

(CH₂)_nNHC(0)0R^x.

In particular R¹ is selected from Ci-₆alkyl, C₃-i₂carbocyclyl (e.g. C₃-i₂cycloalkyl), C₃- i₂heterocarbocyclyl (e.g. C₃-i₂cheterocycloalkyl), C₆-i₂aryl, C₅-i₂heteroaryl, (CH₂)_nC₃-i₂carbocyclyl (e.g. (CH₂)_nC₃-i₂cycloalkyl), (CH₂)_nC₃-i₂heterocarbocyclyl (e.g. (CH₂)_nC₃-i₂heterocycloalkyl), (CH₂)_nC₆-i₂aryl, (CH₂)_nC₅-i₂heteroaryl, C(0)R^x, OR^x, COOR^x, SR^X, C(0)NR^xR^y, NR^xR^y,

NHC(0)R^x, NHC(0)0R^x, Ci-₆haloalkyl, (CH₂)_nC(0)R^x, (CH₂)_nOR^x, (CH₂)_nC(0)0R^x,

(CH₂)_nC(0)NR^xR^y, (CH₂)_nNR^xR^y, (CH₂)_nNHC(0)R^x or (CH₂)_n NHC(0)0R^x. When Y is SiHR¹ or Si(R¹)₂, suitably each R¹ is phenyl or methoxy. n is 1 or 2. R^x and R^y, in each occurrence, are independently selected from H, an optionally substituted Ci- ₆alkyl (e.g. Ci-₆alkyl), an optionally substituted C₃-i₂carbocyclyl (e.g. C₃-i₂carbocyclyl, such as C₃- i₂cycloalkyl), an optionally substituted C₃-i₂heterocarbocyclyl (e.g. C₃-i₂heterocarbocyclyl, such as C₃-i₂cheterocycloalkyl), an optionally substituted C₆-i₂aryl (e.g. C₆-i₂aryl), an optionally substituted C₅-i₂heteroaryl (e.g. C₅-i₂heteroaryl). Suitably, each R^x and R^y is independently selected from H or Ci-₆alkyl, such as H or Ci-₄alkyl.

Alternatively, Y may form a linking group such that at least two (e.g. two or three) structures of formula (I) are covalently attached to each other:

linking group

In such embodiments each W₁, W₂, Z₁ or Z₂ may be the same or different, suitably the same. Desirably X is NH.

Suitable linking groups may include:

In such groups, the point of attachment is suitably in the para-position.

An additional suitable linking group may include:

In such a group, the points of attachment are suitably in the meta-positions.

Y may form a linking group between two structures of formula (I). In such cases the linking group may be Ci-₆alkylene. The linking group may alternatively be phenyl.

In such embodiments each Wi, W₂, Zi or Z₂ are suitably the same. Desirably X is NH. Suitably, the linking group may be Ci-₆alkenylene.

In such an embodiment each W , W₂, Z or Z₂ are suitably the same. Suitably, the linking group may be Ci-₆alkynylene.

In such an embodiment each W , W₂, Z or Z₂ are suitably the same. Y may form a linking group between three structures of formula (I). In such cases the linking group may be a branched or unbranched saturated carbon chain having 1-6 carbon atoms in total. The linking group may alternatively be phenyl.

In such embodiments each Wi, W₂, Zi or Z₂ are suitably the same. Desirably X is NH.

Suitably, the linking group may be a branched or unbranched unsaturated carbon chain having 1-6 carbon atoms in total. Suitably, the linking group may be Ci-₆alkenylene or Ci-₆alkynylene.

For example, the linking group is Ci-₆alkynylene. Alternatively, the linking group is Ci- ₆alkenylene.

Suitably, the term benzoimidazolediol-type linker is selected from the group consisting of:

In one embodiment of the invention the benzoimidazolediol-type linker comprises entially of

and in particular consists of

ment of the invention the benzoimidazolediol-type linker comprises

such as consists essentially of

and in particular consists of

In a third embodiment of the invention the benzoimidazolediol-type linker comprises

such as consists essentially of

and in particular consists of

In a fourth embodiment of the invention the benzoimidazolediol-type linker comprises

such as consists essentially of

and in particular consists of

I t of the invention the benzoimidazolediol-type linker comprises

such as consists essentially of

sists of

In a sixth embodiment of the invention the benzoimidazolediol-type linker comprises

tially of

and in particular consists of

In a seventh embodiment of the invention the benzoimidazolediol-type linker comprises

such as consists essentially of

and in particular consists of

Suitably the benzoimidazolediol-type linker comprises at least two (such as two or three, in particular two) substructures of the formula

wherein R₂ represents a linking group connecting the at least two substructures and wherein the at least two substructures are independently selected from the groups corresponding to L1 to L5 above. The term benzoimidazolediol-type linker as used herein suitably refers to:

or to combinations (either thereof, or with other chemical entities).

In one embodiment of the invention the benzoimidazolediol-type linker comprises 1 H- benzo[c/]imidazole-5,6-diol, such as consists essentially of 1 /-/-benzo[c/]imidazole-5,6-diol and in particular consists of 1 /-/-benzo[c/]imidazole-5,6-diol. In a second embodiment of the invention the benzoimidazolediol-type linker comprises

such as consists essentially of

and in particular consists of

such as consists essentially of

and in particular consists of

such as consists essentially of

and in particular consists of

In some embodiments the benzoimidazolediol-type linker is not 1 /-/-benzimidazole-5, 6- dicarboxylic acid. In some embodiments the benzoimidazolediol-type linker is not 1 /-/- benzimidazole-5, 6-dicarboxylic acid when the metal precursor is a precursor for manganese. In some embodiments the benzoimidazolediol-type linker is not

When the compound contains a Ci-₆alkyl group, whether alone or forming part of a larger group, the alkyl group may be straight chain or branched. Examples of Ci-₄alkyl are methyl, ethyl, propyl (n-propyl and isopropyl) and butyl (n-butyl, isobutyl, sec-butyl and t-butyl). Ci-₆alkyl may be pentyl or hexyl.

The term Ci-₆alkylene group, whether alone or forming part of a larger group, the alkylene group may be straight chain or branched. Examples of Ci_-4alkylene are methylene, ethylene, propylene and butylene. Ci-₆alkylene may also be pentylene or hexylene.

Ci-₆haloalkyl as used herein, such as in Ci_-4haloalkyl is a straight or a branched fully saturated hydrocarbon chain containing the specified number of carbon atoms and at least one halogen atom, such as fluoro or chloro, especially fluoro. Examples of haloalkyl are CF₃, CHF2 and CH2CF₃. Suitably, the at least one halogen atom may be iodo.

Carbocyclyl as used herein is intended to refer to C3-12 (such as a C3-10) saturated or partially saturated (i.e. not containing any aromatic rings) carbocyclic ring systems, for example C3-12 (such as a C3-10) saturated carbocyclic ring systems (i.e. C3-i2cycloalkyl, such as C3-iocycloalkyl). Carbocyclyl may be monocyclic or contain multiple rings (e.g. bicyclic). Rings may be fused or bridged. Examples of C3-i2cycloalkyl include cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl. Aryl as used herein refers to C6-12 mono or polycyclic groups (such as C6-10 mono or bicyclic groups) having from 1 to 3 rings wherein at least one ring is aromatic including phenyl, napthyl, anthracenyl, 5,6,7,8-tetrahydronapthyl and the like, such as phenyl and napthyl. In a bicyclic system the definition of aromatic will be satisfied by the aromatic nature of at least one ring in the system.

Heterocarbocyclyl, as in C3-i2heterocarbocyclyl, is used herein to refer to 3 to 12 membered (such as a 3-10) saturated or partially saturated (i.e. not containing any aromatic rings) ring systems, for example 3 to 12 membered (such as a 3 to 10) saturated ring systems (i.e. C3- i2heterocycloalkyl, such as C3-ioheterocycloalkyl) containing one or more (for example 1 , 2 or 3, in particular 1 or 2) heteroatoms independently selected from O, N and S. Heterocarbocyclyl may be monocyclic or contain multiple rings (e.g. bicyclic). Rings may be fused or bridged. Examples of C3-i2heterocycloalkyl include 5 or 6 or 7 membered rings including pyrrolidine, tetrahydrofuran, tetrahydrothiophene, piperidine, piperazine, morpholine, 1 ,4-dioxane, pyrrolidine and oxoimidazolidine.

Heteroaryl as used herein refers to 6 to 12 membered mono or polycyclic groups (such as 6 to 10 membered mono or bicyclic groups) having from 1 to 3 rings wherein at least one ring is aromatic and containing one or more (for example 1 , 2, 3 or 4, such as 1 , 2 or 3) heteroatoms independently selected from O, N and S. Examples of heteroaryls include: pyrrole, oxazole, thiazole, isothiazole, imidazole, pyrazole, isoxazole, pyridazine, pyrimidine, pyrazine, benzothiophene, benzofuran, or 1 ,2,3- and 1 ,2,4-triazole. In a bicyclic ring system the definition of heteroaryl will be satisfied if at least one ring contains a heteroatom and at least one ring is aromatic. The heteroaryl may be linked to the remainder of the molecule through a carbocyclic ring or a ring comprising a heteroatom.

Optionally substituted, when referring to substitution of an alkyl, carbocyclyl, heterocarbocyclyl, aryl or heteroaryl group suitably means one or more (e.g. one, two or three, such as one or two, especially one) groups each independently selected from OH, COOH, halo (e.g. chloro, fluoro or bromo) and NH2. Suitably, halo may be iodo.

As the functionalities of the benzoimidazolediol-type linker allow, the linker may be provided in the form of a salt.

Metal precursor

The term metal precursor as used herein refers to a suitable source of metal ions. The metal ion may be selected from the group consisting of Group 1 through 16 metals of the IUPAC Periodic Table of the Elements including actinides, and lanthanides. Examples of suitable metal ions include Li⁺, Na⁺, K⁺, Rb⁺, Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sc³⁺, Y³⁺, Ti⁴⁺, ZH⁺, Hf⁴⁺, V⁴⁺, V³⁺, V²⁺, Nb³⁺, Ta³⁺, Cr³⁺, Mo³⁺, W³⁺, Mn³⁺, Mn²⁺, Re³⁺, Re²⁺, Fe³⁺, Fe²⁺, Ru³⁺, Ru²⁺, Os³⁺, Os²⁺, Co³⁺, Co²⁺, Rh²⁺, Rh⁺, lr²⁺, lr⁺, Ni²⁺, NG, Pd²⁺, Pd⁺, Pt²⁺, Pt⁺, Cu²⁺, Cu⁺, Ag⁺, Au⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺, Ga³⁺, ln³⁺, Tl³⁺, Si⁴⁺, Si²⁺, Ge⁴⁺, Ge²⁺, Sn⁴⁺, Sn²⁺, Pb⁴⁺, Pb²⁺, As⁵⁺, As³⁺ , As⁺ , Sb⁵⁺ , Sb³⁺ , Sb⁺ , Bi⁵⁺ , Bi³⁺ , Bi⁺. Other suitable metal ions include Au³⁺, Ag³⁺ and Ag²⁺. Suitable metal ions include TG, Pt⁴⁺ and Pd⁴⁺. The term metal ions, as used herein, also encompasses metalloids such as boron (e.g. B³⁺) and silicon (Si⁴⁺). In particular, the metal ion may be selected from Co, Cu, Fe, Mn and Ni. Another metal precursor of interest is a source of Zn ions. In one embodiment the metal precursor consists essentially of, such as consists of, a single source of metal ions. In a second embodiment the metal precursor comprises a plurality of sources of a single metal ion, such as consists essentially of a plurality of sources of a single metal ion, such as consists of a plurality of sources of a single metal ion (e.g. a mix of Fe (III) salts). In a third embodiment, the metal precursor comprises a source or sources for a plurality of metal ions (e.g. which may be different forms of a single metal, such as Fe (III) and Fe (II), or may be different metals, such as Fe and Cu).

Suitably the metal precursor comprises a source or sources of a plurality of metal ions wherein at least one metal ion is selected from the group consisting of Co, Cu, Fe, Mn, Ni and Zn, such as Co, Fe and Zn ions. Suitably, the plurality of metal ions comprises Fe, such as Fe(lll) and Zn, such as Zn(ll). Suitably, the plurality of metal ions comprises Co, such as Co(ll) and Zn, such as Zn(ll). Suitably, the plurality of metal ions comprises Fe, such as Fe(lll) and Co, such as Co(ll).

The metal precursor will typically be a salt of the desired metal ion. Suitable salts may be organic salts or inorganic salts. Inorganic salts include sulfate, nitrate, nitrite, sulfite, bisulfite, phosphate, hydrogen phosphate, dihydrogen phosphate, diphosphate, triphosphate, phosphite, chloride, chlorate, bromide, bromate, iodide, iodate, carbonate, bicarbonate, sulfide, hydrogen sulphate, selenide, selenate, hydrogen selenate, telluride, tellurate, hydrogen tellurate, nitride, phosphide, arsenide, arsenate, hydrogen arsenate, dihydrogen arsenate, antimonide, antimonate, hydrogen antimonate, dihydrogen antimonate, fluoride, boride, borate, hydrogen borate, perchlorate, chlorite, hypochlorite, perbromate, bromite, hypobromite, periodate, iodite, hypoiodite. Other salts may include molybdate, isopropoxide, methoxide, ethoxide, pivalate and acetate.

In one embodiment the metal precursor is a precursor for Fe, such as a salt of iron, in particular Fe(lll), such as FeC . In a second embodiment the metal precursor is a precursor for Ni, such as a salt of nickel, in particular Ni(ll), such as NiCh. In a third embodiment the metal precursor is a precursor for Co, such as a salt of cobalt, in particular Co(ll), such as C0CI₂. In a fourth embodiment the metal precursor is a precursor for Mn, such as a salt of manganese, in particular Mn(ll), such as MnCh. In a fifth embodiment the metal precursor is a precursor for Cu, such as a salt of copper, in particular Cu(ll), such as CuCh. In a sixth embodiment the metal precursor is a precursor of zinc, such as a salt of zinc, in particular Zn(ll), such as ZnCh.

In some embodiments the metal precursor is not a precursor for cobalt ions. In other embodiments the metal precursor is not a precursor for zinc ions. In some embodiments the metal precursor does not comprise a precursor for cobalt ions. In some embodiments the metal precursor does not comprise a precursor for zinc ions.

In some embodiments the metal precursor is not MnCh when the benzoimidazolediol-type linker 1 /-/-benzimidazole-5, 6-dicarboxylic acid, in particular the metal precursor is not a precursor for manganese ions when the benzoimidazolediol-type linker is 1 /-/-benzimidazole-5, 6-dicarboxylic acid. Suitably, the metal precursor is not MnCh, in particular the metal precursor is not a precursor for manganese ions.

Reacting a metal precursor with a benzoimidazolediol-type linker

By the term reacting a metal precursor with a benzoimidazolediol-type linker is meant the formation of an amorphous or crystalline MOF incorporating metal ions and the benzoimidazolediol-type linker.

Reacting may take place in any suitable solvent. Typically, the solvent will be a single phase system. Suitably the metal precursor and benzoimidazolediol-type linker fully dissolve in the solvent, consequently MOF formation provides a precipitate which may be readily isolated. The solvent may be single component (e.g. water or an organic components) or may comprise a plurality of components. The plurality of components may be a mixture of organic components or a mixture of water and one or more organic components. The optimal solvent may depend on the choice of metal precursor and the benzoimidazolediol-type linker. Example organic components will typically be polar in nature and include diethyl formamide (DEF), dimethyl formamide (DMF), ethanol and methanol, in particular DMF. An example of a single phase multi-component solvent is a mixture of water and DMF, such as in the range 2:1 and 1 :2 v/v, in particular about 1 :1 , such as 1 :1 . The solvent may be a single component (e.g. water or an inorganic component) or may comprise a plurality of components. The plurality of components may be a mixture of inorganic components or a mixture of water and one or more inorganic components. The plurality of components may be a mixture of inorganic components, water and one or more organic components. The plurality of components may be a mixture of inorganic components and organic components. An example inorganic component is ammonia. An example of a single phase multi- component solvent is a mixture of water and ammonia. Suitably, the solvent is aqueous ammonia.

Reacting may take place at any suitable temperature. Elevated temperatures may expedite the reaction process. The optimal temperature may vary depending on the chosen metal precursor, benzoimidazolediol-type linker and solvent. The temperature will typically be in the range of 20- 200 degrees C, such as 70-120 degrees C, in particular 80-1 10 degrees C. The reaction suitably is allowed to continue for an adequate period of time such that it is close to or has gone to completion. The optimal period of time may vary depending on other parameters. Typically, the metal precursor is reacted with benzoimidazolediol-type linker for a period of up to 14 days, such as 1 hour to 14 days, in particular 4 hours to 12 days, especially 1 day to 6 days, for example about 3 days, such as 3 days.

As described in the Examples herein, variation of the relative amounts of metal/organic linker in the reaction mixture may not significantly impact the composition of the catalyst precursor which is obtained. Consequently, although the molar ratio of metal ions to benzoimidazolediol-type linker will typically be in the ratio 10:1 to 1 :10, conveniently the ratio of molar ratio of metal ions to benzoimidazolediol-type linker will be 2:1 to 1 :2 (e.g. about 1 :1 , such as 1 :1 ). The optimal ratio will depend on the nature of the benzoimidazolediol-type linker.

A further aspect of the present invention is therefore a solution comprising a metal precursor and benzoimidazolediol-type linker as described herein.

Catalytic precursor

Reacting the metal precursor with the benzoimidazolediol-type linker leads to the formation of the catalytic precursor. Both the catalyst precursor per se and methods described herein for the formation of the catalyst precursor are aspects of the present invention.

Consequently, the present invention provides a catalyst precursor obtainable by, and in particular as obtained by, the methods described herein.

In an embodiment there is provided a catalyst precursor comprising Fe, Ni, Co, Mn and/or Cu metal ions and a benzoimidazolediol-type linker, in particular 1 /-/-benzo[c/]imidazole-5,6-diol.

Also provided is a crystalline catalyst precursor derived from Fe(lll) and 1 /-/-benzo[c/]imidazole- 5,6-diol and having an x-ray diffraction pattern with 2Q peaks at at least three, such as at least five, in particular at least seven and especially all nine of 15.1 °, 15.62°, 16.48°, 17.68°, 18.38°, 24,78°, 26.79°, 28.34° and 28.94° (±0.2).

The catalyst precursor is a solid and may conveniently be isolated from the reaction mixture by methods such as filtration or centrifugation. After isolation the collected material may be dried to remove residual solvent. In some embodiments the catalyst precursor is crystalline, in other embodiments the catalyst precursor is amorphous.

The catalyst precursor will typically have limited catalytic capability.

Carbonisation

Catalytic precursor material is carbonised to provide improved properties. These improved properties may be a combination of physical properties (e.g. stability) and catalytic properties (e.g. conductivity).

Carbonisation may be undertaken by heating at a suitable temperature, for example a temperature in the range of 400 to 1500 degrees C, in particular 700 to 1200 degrees C, especially 700 to 1 100 degrees C, suitably about 800 degrees C (such as 800 degrees C) or about 1000 degrees C (such as 1000 degrees C). A further temperature of interest is about 900 degrees C (such as 900 degrees C). Carbonisation may occur under conditions where the temperature is maintained at a consistent level or where it is varied (e.g. increasing, decreasing or a combination of increasing and decreasing, stepwise or linear/non-linear gradient-wise), during carbonisation.

The chemical and structural changes induced by heating may be facilitated by other means of energy input, such as ball milling, the application of microwave energy and the like.

Carbonisation may be undertaken in any suitable environment, which in some circumstances may be a reactive atmosphere (e.g. comprising N H3) or may be an inert atmosphere (e.g. under nitrogen). Carbonisation may also occur under environmental conditions which are varied. Suitably, carbonisation may be undertaken in a reactive atmosphere (e.g. comprising H2).

Carbonisation may be undertaken for any suitable time period, such as for 1 minute to 72 hours, in particular 1 hour to 4 hours, such as about 2 hours (e.g. 2 hours).

Optimal carbonisation conditions may vary depending on the identity of the metal ion, linker and the desired properties of the resulting catalytic material.

Catalytic material

The catalytic material will typically comprise substantial amounts of carbon which is derived from the benzoimidazolediol-type linker, suitably at least 75% of the carbon in the catalytic material is derived from the benzoimidazolediol-type linker, especially at least 80%, in particular at least 90%, for example at least 95%, such as at least 98% or at least 99% on a molar basis.

Other modifications

Doping provides a mechanism to introduce other materials into the catalyst precursor and/or the catalytic material. Doping can alter or enhance certain properties of the catalyst precursor and/or the catalytic material. This can be done at any appropriate point in the methods of the present invention and may depend on the nature of the material to be introduced and the effect which is to be obtained e.g. (i) during reaction of the metal precursor and the benzoimidazolediol-type linker (ii) after formation of the catalyst precursor but before carbonisation (iii) during carbonisation (iv) after carbonisation. In one embodiment the catalytic material is doped. In a second embodiment the catalytic material is undoped. The method of the invention therefore may include an optional step of doping.

Leaching, such as acid leaching e.g. using sulfuric, nitric acid and/or acid mixtures comprising one or both of these, can be used. Acid leaching can remove excess metal ions, or provide other modifications, which result in a desirable change in properties. The method of the invention therefore may include an optional step of leaching, such as acid leaching.

As described in the examples herein, catalytic material may be applied to a supporting structure after formation of the catalytic material. However, support suitable structures may be introduced at earlier stages in the method e.g. (i) during reaction of the metal precursor and the benzoimidazolediol-type linker (ii) after formation of the catalyst precursor but before carbonisation. The use of a supporting structure may facilitate handling and/or enable properties which the catalytic material is unable to achieve in the absence of such supporting structures. Exemplary supporting structures include e.g. carbon black, nanoobjects (nanoparticles, nanodots, carbon dots), polymers, silica, zeolites, alum and textiles and the like. Supporting structures may be sacrificial in nature and removed during or after formation of catalytic material. In one embodiment the catalytic material is supported. In a second embodiment the catalytic material is unsupported.

It is to be understood that the present invention encompasses all isomers, including all geometric, tautomeric and optical forms, and mixtures thereof.

The subject invention also includes isotopically-labelled compounds wherein one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number most commonly found in nature. The skilled person will appreciate that in many circumstances the proportion of an atom having an atomic mass or mass number found less commonly in nature can also be been increased (referred to as“isotopic enrichment”).

General Synthesis Schemes

The following schemes detail general synthetic routes to benzoimidazolediol-type linkers of use in the invention and intermediates in the synthesis of such compounds. In the following schemes reactive groups can be protected with protecting groups and deprotected according to established techniques well known to the skilled person.

Novel linkers and intermediates form a further aspect of the present invention.

1 /-/-benzo[c/]imidazole-5,6-diol may be prepared by published methods (Fan, 2016) or the methods exemplified herein.

The catalytic material may be used in the catalysis of a chemical reaction. As demonstrated in the examples herein, a suitable example of a reaction which may be catalysed is the oxygen reduction reaction (ORR). Other electrochemical processes where the catalysts may have utility include hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Catalytic material may also be of use in CO2 uptake. Catalytic material may additionally have utility in other chemical processes, such as chemical conversion catalysis (i.e. conventional synthesis), reduction, oxidation, (trans)esterification and the like. Other uses of the catalytic material may be in water splitting, carbon monooxide and carbon dioxide conversions or nitrogen fixation.

In use, catalytic material may be provided as-is (i.e. unsupported) or may be supported.

In some embodiments the catalytic material is provided in the form of an electrode. Also provided are fuel cells comprising electrodes which comprise the catalytic material.

In some embodiments the catalytic material is provided in the form of a supercapacitor comprising electrodes which comprise the catalytic material. In another embodiment the catalytic material is provided in the form of a metal-air battery comprising electrodes which comprise the catalytic material.

The invention is further illustrated by the following clauses:

Clause 1. A method for forming a catalytic precursor, said method comprising the step of reacting a metal precursor with a benzoimidazolediol-type linker.

Clause 2. A method for forming a catalytic material, said method comprising the

carbonisation of a catalyst precursor obtainable by reacting a metal precursor with a

benzoimidazolediol-type linker.

Clause 3. A method for forming a catalytic material, said method comprising the steps:

(b) carbonisation of the catalyst precursor.

Clause 4. The method according to any one of clauses 1 to 3, wherein the

benzoimidazolediol-type linker comprises, such as consists of, a compound of formula (I):

wherein

X is selected from NH, O and S;

or a salt thereof.

Clause 5. The method according to any one of clauses 1 to 3, wherein the

wherein

Wi and W₂ are each independently selected from OH, NH2, SH, COOH, B(OH)2, Si(OH)3, CN, CºCH and CONH₂;

X is selected from NH, O and S;

Zi and Z2 are each independently H or may be any substituent which allows the compound to retain ability to form a catalyst precursor and catalytic material; and

Y is selected from CH or a group which allows the compound to retain ability to form a catalyst precursor and catalytic material;

or a salt thereof.

Clause 6. The method according to any one of clauses 1 to 3, wherein the

wherein

Wi and W2 are each independently selected from OH, NH2, SH, COOH, B(OH)2, Si(OH)₃, CN, CºCH, CONH2, OCH₃, Ci-₆alkyl and halo;

X is selected from NH, O and S;

with the proviso that the compound is not 1 /-/-benzimidazole-5, 6-dicarboxylic acid; or a salt thereof.

Clause 7. The method according to any one of clauses 1 to 3, wherein the

wherein

X is selected from NH, O and S;

Clause 8. The method according to any one of clauses 4 to 7, wherein Wi and W2 are the same.

Clause 9. The method according to any one of clauses 4 to 8, wherein Wi is OH.

Clause 10. The method according to clause 9, wherein Wi and W2 are OH.

Clause 11. The method according to clause 4 to 8, wherein Wi is COOH.

Clause 12. The method according to clause 1 1 , wherein Wi and W2 are COOH.

Clause 13. The method according to any one of clauses 4 to 7 wherein at least one of Wi and W2 is OH.

Clause 14. The method according to any one of clauses 4 to 7 wherein at least one of Wi and W₂ is COOH.

Clause 15. The method according to any one of clauses 4 to 7 wherein at least one of Wi and W2 is OCH3. Clause 16. The method according to any one of clauses 4 to 7 wherein at least one of Wi and W₂ is NH2.

Clause 17. The method according to any one of clauses 4 or 6 wherein at least one of Wi and W2 is halo, especially F.

Clause 18. The method according to any one of clauses 4 or 6 wherein at least one of Wi and W2 is Ci-₆alkyl, especially CH₃.

Clause 19. The method according to clause 15, wherein Wi is OCH3.

Clause 20. The method according to clause 16, wherein Wi is IMH2.

Clause 21 . The method according to clause 17, wherein Wi is halo, especially F.

Clause 22. The method according to clause 18, wherein Wi is Ci-₆alkyl, especially CH₃.

Clause 23. The method according to any one of clauses 13 to 22, wherein W2 is OH.

Clause 24. The method according to any one of clause 13 to 22, wherein W2 is COOH.

Clause 25. The method according to any one of clauses 13 to 22, wherein W2 is OCH₃.

Clause 26. The method according to any one of clauses 13 to 22, wherein W2 is NH2.

Clause 27. The method according to any one of clauses 13 to 22, wherein W2 is halo, especially F.

Clause 28. The method according to any one of clauses 13 to 22, wherein W2 is Ci-₆alkyl, especially CH3.

Clause 29. The method according to any one of clauses 1 to 28, wherein X is NH.

Clause 30. The method according to any one of clauses 1 to 29, wherein Z1 and Z₂ are the same. Clause 31. The method according to any one of clauses 1 to 30, wherein Zi is H, optionally substituted Ci-₆alkyl, optionally substituted phenyl, halo or NR^xR^y, wherein R^x and R^y, in each occurrence, are independently selected from H, optionally substituted Ci-₆alkyl, optionally substituted C3-i2carbocyclyl, optionally substituted C3-i2heterocarbocyclyl, optionally substituted C6-i2aryl or optionally substituted C5-i2heteroaryl.

Clause 32. The method according to clause 31 , wherein Zi is optionally substituted Ci-₆alkyl (e.g. Ci-₆alkyl).

Clause 33. The method according to clause 31 , wherein Zi is optionally substituted phenyl (e.g. phenyl).

Clause 34. The method according to clause 31 , wherein Zi is H.

Clause 35. The method according to any one of clauses 1 to 34, wherein Z₂ is H, optionally substituted Ci-₆alkyl, optionally substituted phenyl, halo or NR^xR^y, wherein R^x and R^y, in each occurrence, are independently selected from H, optionally substituted Ci-₆alkyl, optionally substituted C3-i2carbocyclyl, optionally substituted C3-i2heterocarbocyclyl, optionally substituted C6-i2aryl or optionally substituted C5-i2heteroaryl.

Clause 36. The method according to clause 35, wherein Z₂ is optionally substituted Ci-₆alkyl (e.g. Ci-₆alkyl).

Clause 37. The method according to clause 35, wherein Z₂ is optionally substituted phenyl (e.g. phenyl)

Clause 38. The method according to clause 35, wherein Z₂ is H.

Clause 39. The method according to any one of clauses 1 to 38, wherein Y is CH.

Clause 40. The method according to any one of clauses 1 to 38, wherein Y is CR¹.

Clause 41. The method according to any one of clauses 1 to 38, wherein Y is BH.

Clause 42. The method according to any one of clauses 1 to 38, wherein Y is BR¹. Clause 43. The method according to any one of clauses 1 to 38, wherein Y is Sihh.

Clause 44. The method according to any one of clauses 1 to 38, wherein Y is SiHR¹ or

Si(R¹)₂.

Clause 45. The method according to any one of clauses 40, 42 or 44, wherein R¹ is selected from Ci-₆alkyl, C3-i2carbocyclyl (e.g. C3-i2cycloalkyl), C3-i2heterocarbocyclyl (e.g. C3- i2cheterocycloalkyl), C6-i2aryl, C5-i2heteroaryl, (CH2)_nC3-i2carbocyclyl (e.g. (CH2)_nC3-i2cycloalkyl),

Clause 46. The method according to any one of clauses 40, 42, 44 or 45 wherein n is 1 .

Clause 47. The method according to any one of clauses 40, 42, 44 or 45 wherein n is 2.

Clause 48. The method according to any one of clause 31 , 35, 40, 42 or 44 to 47, wherein each R^x and R^y is independently selected from H or Ci-₆alkyl.

Clause 49. The method according to clause 45 wherein R1 is Ci-₆alkyl, such as CH3.

Clause 50. The method according to clause 45 wherein R1 is Ci-₆haloalkyl, such as CF3. Clause 51 . The method according to any one of clauses 1 to 38, wherein Y forms a linking group:

Clause 52. The method according to clause 51 , when the linking group is phenyl. Clause 53. The method according to clause 51 , when the linking group is a Ci-₆ branched or unbranched saturated carbon chain.

Clause 54. The method according to clause 51 , wherein the linking group is a Ci-₆ branched or unbranched unsaturated carbon chain, such as Ci-₆alkenylene or Ci-₆alkynylene.

Clause 55. The method according to clause 54, wherein the linking group is Ci-₆alkenylene.

Clause 56. The method according to clause 54, wherein the linking group is Ci-₆alkynylene. Clause 57. The method according to any one of clauses 51 to 56, wherein each Wi, W₂, Zi or Z₂ are the same.

Clause 58. The method according to any one of clauses 1 to 7 and 51 to 57, wherein the benzoimidazolediol-type linker comprises at least two substructures of the formula

wherein

R₂ represents a linking group connecting the at least two substructures and wherein the at least two substructures are independently selected from the groups corresponding to L1 to L5

Clause 59. The method according to any one of clauses 1 to 3, wherein the

benzoimidazolediol-type linker comprises 1 /-/-benzo[c/]imidazole-5,6-diol, such as consists of 1 /-/-benzo[c/]imidazole-5,6-diol.

Clause 60. The method according to any one of clauses 1 to 3, wherein the

benzoimidazolediol-type linker comprises

Clause 61 . The method according to any one of clauses 1 to 3, wherein the

benzoimidazolediol-type linker comprises

such as consists of

Clause 62. The method according to any one of clauses 1 to 3, wherein the benzoimidazolediol-type linker comprises

Clause 63. The method according to any one of clauses 1 to 3, wherein the benzoimidazolediol-type linker comprises a linker selected from the group consisting of

Clause 64. The method according to clause 63, wherein the benzoimidazolediol-type linker comprises

Clause 65. The method according to clause 63, wherein the benzoimidazolediol-type linker comprises

such as consists of

Clause 66. The method according to clause 63, wherein the benzoimidazolediol-type linker comprises

such as consists of

Clause 67. The method according to clause 63, wherein the benzoimidazolediol-type linker comprises

such as consists of

method according to clause 63, wherein the benzoimidazolediol-type linker

such as consists of

hod according to clause 63, wherein the benzoimidazolediol-type linker

such as consists of

Clause 70. The method according to clause 63, wherein the benzoimidazolediol-type linker comprises

Clause 71 . The method according to any one of clauses 1 to 70, wherein the metal precursor is a single source of metal ions.

Clause 72. The method according to any one of clauses 1 to 70, wherein the metal precursor is a plurality of sources of a single metal ion.

Clause 73. The method according to any one of clauses 1 to 70, wherein the metal precursor comprises a source or sources for a plurality of metal ions.

Clause 74. The method according to clause 73, wherein the plurality of metal ions are different forms of a single metal.

Clause 75. The method according to clause 73, wherein the plurality of metal ions are different metals.

Clause 76. The method according to any one of clauses 1 to 75, wherein the metal precursor is a source of metal ions selected from the group consisting of Li⁺, Na⁺, K⁺, Rb⁺, Be²⁺, Mg²⁺,

Clause 77. The method according to any one of clauses 1 to 75, wherein the metal precursor is a source of metal ions selected from the group consisting of Au³⁺, Ag³⁺, Ag²⁺, TG, Pt⁴⁺ and Pd⁴⁺.

Clause 78. The method according to any one of clauses 1 to 75, wherein the metal precursor is a source of metal ions selected from the group consisting of boron and silicon. Clause 79. The method according to any one of clauses 1 to 78, wherein the metal precursor is a metal salt.

Clause 80. The method according to clause 79, wherein the metal salt is a salt of iron.

Clause 81. The method according to clause 79, wherein the metal salt is a salt of cobalt.

Clause 82. The method according to clause 79, wherein the metal salt is a salt of nickel.

Clause 83. The method according to clause 79, wherein the metal salt is a salt of

manganese

Clause 84. The method according to clause 79, wherein the metal salt is a salt of copper.

Clause 85. The method according to clause 79, wherein the metal salt is a salt of zinc.

Clause 86. The method according to clause 75 or clause 76, wherein the metal precursor is a source or sources of a plurality of metal ions, such as selected from the group consisting of Fe, Co and Zn.

Clause 87. The method according to clause 86, wherein the plurality of metal ions comprises Fe³⁺ and Zn²⁺.

Clause 88. The method according to clause 86, wherein the plurality of metal ions comprises Co²⁺ and Zn²⁺.

Clause 89. The method according to clause 86, wherein the plurality of metal ions comprises Fe³⁺ and Co²⁺.

Clause 90. The method of any one of clauses 1 to 89, wherein the metal precursor is reacted with benzoimidazolediol-type linker in a solvent mixture containing dimethylformamide (DMF).

Clause 91. The method of any one of clauses 1 to 90, wherein the metal precursor is reacted with benzoimidazolediol-type linker in a solvent mixture containing water. Clause 92. The method of clause 91 , wherein the metal precursor is reacted with

benzoimidazolediol-type linker in a solvent mixture containing water and DMF.

Clause 93. The method of clause 92, wherein the metal precursor is reacted with

benzoimidazolediol-type linker in a solvent mixture containing water and DMF in the range 2:1 and 1 :2 v/v.

Clause 94. The method of any one of clauses 1 to 93, wherein the metal precursor is reacted with benzoimidazolediol-type linker at a temperature of 70-120 degrees C.

Clause 95. The method of clause 94, wherein the metal precursor is reacted with

benzoimidazolediol-type linker at a temperature of 80-1 10 degrees C.

Clause 96. The method of any one of clauses 1 to 95, wherein the metal precursor is reacted with benzoimidazolediol-type linker for a period of 4 hours to 12 days.

Clause 97. The method of clause 96, wherein the metal precursor is reacted with

benzoimidazolediol-type linker for a period of 1 day to 6 days.

Clause 98. The method of any one of clauses 1 to 97, wherein the metal precursor is reacted with benzoimidazolediol-type linker at a metal to benzoimidazolediol-type linker molar ratio of 10:1 to 1 :10.

Clause 99. The method of clause 98, wherein the metal precursor is reacted with

benzoimidazolediol-type linker at a metal to benzoimidazolediol-type linker molar ratio of 2:1 to 1 :2.

Clause 100. The method of any one of clauses 3 to 99, comprising the steps:

(a) reacting a metal precursor with benzoimidazolediol-type linker to form a catalyst precursor;

(b) isolation of the catalyst precursor;

(c) carbonisation of the catalyst precursor.

Clause 101. The method of clause 100, wherein isolation comprises separating the catalyst precursor from the reaction mixture by filtration. Clause 102. The method of either clause 100 or clause 101 , wherein isolation comprises drying the catalyst precursor.

Clause 103. The method of any one of clauses 2 to 102, wherein the carbonisation is undertaken at a temperature of between 400 degrees C and 1500 degrees C.

Clause 104. The method of clause 103, wherein the carbonisation is undertaken at a temperature of between 700 degrees C and 1100 degrees C.

Clause 105. The method of any one of clauses 2 to 104, wherein the carbonisation is undertaken in an inert atmosphere.

Clause 106. The method of clause 105, wherein the carbonisation is undertaken under nitrogen.

Clause 107. The method of any one of clauses 2 to 106, wherein the carbonisation is undertaken for a period of 30 minutes to 24 hours.

Clause 108. The method of clause 107, wherein the carbonisation is undertaken for a period of 1 hour to 4 hours.

Clause 109. The method of any one of clauses 2 to 108, wherein the carbonisation is undertaken at constant temperature.

Clause 110. The method of any one of clauses 2 to 108, wherein the carbonisation is undertaken at varying temperature.

Clause 11 1. The method of any one of clauses 1 to 110, comprising the additional step of doping.

Clause 112. The method of any one of clauses 2 to 11 1 , comprising the additional step of leaching, such as acid leaching.

Clause 113. The method of any one of clauses 1 to 112, wherein the benzoimidazolediol-type linker is not 1 /-/-benzimidazole-5, 6-dicarboxylic acid. Clause 114. The method of any one of clauses 1 to 113, wherein the metal precursor is not MnCh, in particular the metal precursor is not a precursor for manganese ions.

Clause 115. A catalyst precursor obtainable by the method of any one of clauses 1 or 4 to 102.

Clause 116. Catalytic material obtainable by the method of any one of clauses 2 to 114.

Clause 117. Use of a benzoimidazolediol-type linker, in particular 1 /-/-benzo[c/]imidazole-5,6- diol, in the manufacture of a catalyst.

Clause 118. Use of a catalyst precursor according to clause 115 in the manufacture of a catalyst.

Clause 119. Use of catalytic material according to clause 1 16 to catalyse a chemical reaction.

Clause 120. A method for the catalysis of a chemical reaction comprising the steps:

(a) forming catalytic material according to clause 116; and

(b) catalysing the chemical reaction using said catalytic material.

Clause 121. The method of clause 120, wherein the catalytic material is obtained from the method of any one of clauses 2 to 1 14.

Clause 122. The use or method according to any one of clauses 1 19 to 121 , wherein the chemical reaction is ORR.

Clause 123. The use or method according to any one of clauses 1 19 to 121 , wherein the chemical reaction is HER.

Clause 124. The use or method according to any one of clauses 1 19 to 121 , wherein the chemical reaction is OER.

Clause 125. The use or method according to any one of clauses 1 19 to 121 , wherein the chemical reaction is a reduction. Clause 126. The use or method according to any one of clauses 1 19 to 121 , wherein the chemical reaction is oxidation.

Clause 127. The use or method according to any one of clauses 1 19 to 121 , wherein the chemical reaction is an esterification or transesterification.

Clause 128. The use or method according to any one of clauses 1 19 to 121 , wherein the chemical reaction is CO2 uptake.

Clause 129. An electrode comprising catalytic material according to clause 1 16.

Clause 130. A fuel cell comprising an electrode according to clause 129.

Clause 131. A solution comprising a metal precursor and benzoimidazolediol-type linker.

Clause 132. The solution according to clause 131 , wherein the solution comprises a single phase mixture of water and an organic component.

Clause 133. The solution according to either clause 131 or 132, wherein the solution comprises water and DMF.

Experimental

The invention is illustrated by the examples described below, which are not meant to limit the scope of the invention in any way with respect to materials, processes or uses. It is understood that, although specific reagents, solvents, temperatures and time periods are used, there are many possible equivalent alternatives that can be used to produce similar results. This invention is intended to include such equivalents.

Example 1 - Preparation of Fe(lll) 1H-benzo[cf]imidazole-5,6-diol catalyst precursor

(i) Preparation of 1 /-/-benzorc/limidazole-5,6-diol

1 /-/-benzo[c/]imidazole-5,6-diol was prepared by similar methods to those found in the literature (Fan, 2016).

Briefly:

1, 2-Dimethoxy-4, 5-dinitrobenzene

1 .2-Dimethoxybenzene (1 1 .08 g, 80.19 mmol, 1 .0 equiv) was added dropwise into cone. HNO3 (100 ml_, 65%) at 0 °C, after addition, the mixture was left to stir at 80 °C. After 2 h, the mixture was cooled down to 0 °C, and the resulting precipitate was washed with distilled water until neutral to give the title compound as a yellow needle crystal (15.39 g, 67.45 mmol, 84%).

¹H NMR (400 MHz, CDCI3) d 7.33 (s, 2H), 4.01 (s, 6H).

¹³C NMR (100 MHz, CDCI3) 6152.0, 136.8, 107.1 , 57.2.

5, 6-Dimethoxy- 1 H-benzo[d]imidazole (L3)

Hydrazine monohydrate (22.6 ml_, 464.7 mmol, 10.8 equiv) was added dropwise to a solution of

1 .2-dimethoxy-4, 5-dinitrobenzene (9.85 g, 43.2 mmol, 1.0 equiv) and Pd/C (10%, 0.985 g) in anhydrous EtOH (60 ml.) at 0 °C, after addition, the mixture was left to stir at 80 °C. After 30 min, the mixture was filtered through silica gel, concentrated under reduced pressure, to which formic acid (98%, 100 ml.) was added, and the mixture was left to stir at 100 °C. After 16 h, the mixture was concentrated under reduced pressure, water (50 ml.) added, and the solution was basified with solid K2CO3. The precipitate was collected, washed with water and dried to give the title compound as a colourless solid (7.00 g, 39.3 mmol, 91 %).

¹H NMR (400 MHz, DMSO-de) 6 8.03 (s, 1 H), 7.14 (s, 2H), 3.82 (s, 6H).

¹³C NMR (100 MHz, DMSO-de) 6 147.2, 141.1 , 132.5, 99.2, 56.8.

1 H-Benzo[d]imidazole-5, 6-diol (L1)

5,6-Dimethoxy-1 /-/-benzo[c/]imidazole (7.79 g, 43.7 mmol, 1 .0 equiv) was added into HBr (48%, 50 ml_), and the mixture was left to stir at 120 °C. After 4 h, the mixture was cooled down to 0 °C, and the precipitate was collected, washed with petroleum ether to give the desired compound as a colourless solid (4.59 g, 30.6 mmol, 70%).

¹H NMR (400 MHz, DMSO-de) 6 9.75 (s, 2H), 9.25 (s, 1 H), 7.12 (s, 2H).

¹³C NMR (100 MHz, DMSO-de) 6 146.4, 136.9, 123.7, 98.4.

(ii) Preparation of Fe(lll) 1 /-/-benzorc/1imidazole-5, 6-diol catalyst precursor FeCl_3'6H₂0 (90 mg, 0.333 mmol, 1 .0 equiv) and 1 /-/-benzo/c//imidazole-5,6-diol (100 mg, 0.666 mmol, 2.0 equiv) were dissolved in a mixture of DMF/water (1.5 mL/1.5 ml_), and the mixture left to react at 100 °C. After 3 days, the mixture was cooled to room temperature, centrifuged, washed with DMF (3x5 ml_), and dried (1 10 °C, 16 h) to give a black solid (48 mg), referred to herein as TAL-001 .

Example 2 - Preparation of Fe(lll) 1 H-benzo[cf]imidazole-5,6-diol derived catalytic material

Fe(lll) 1 /-/-benzo[c/]imidazole-5,6-diol catalyst precursor, prepared according to Example 1 , was pyrolysed at 800 °C for 2 h under N₂, after which the sample was allowed to cool down gradually to give Fe(lll) 1 /-/-benzo[c/]imidazole-5,6-diol derived catalytic material referred to herein as TAL- 001 C@800.

The as-prepared catalytic material TAL-001 C@800 was dispersed ultrasonically in 0.05 wt% Nafion solution in anhydrous ethanol to a concentration of 10 mg mL^_1. 2.5 pL of the suspension were deposited onto 4 mm diameter glassy carbon (GC) disk electrodes, resulting in catalyst loading of 800 pg per cm² of geometric electrode area.

Example 3 - Characterisation of Fe(lll) 1 H-benzo[cf]imidazole-5,6-diol catalyst precursor TAL-001 and Fe(lll) 1 H-benzo[d]imidazole-5,6-diol derived catalytic material TAL-

001 C@800

Methods

XRD

XRD patterns were recorded on a Rigaku Ultima IV diffractometer with Cu Ka radiation (l = 1.5406 A, 40 kV at 40 mA) and using the silicon strip detector D/teX Ultra with the scan range of 2Q = 10.0-60.0 deg, scan step 0.02 deg, scan speed 5 deg/min. The scan axes were 2 Q/Q.

HR-SEM

Surface morphology was studied using scanning electron microscopy (SEM) analysis using Zeiss Ultra-55 and Helios TM NanoLab 600 (FEI) microscopes. A suspension of the catalyst in isopropanol was deposited onto a GC disk and dried to prepare a sample for SEM investigation.

XPS

The surface elemental composition was investigated by X-ray photoelectron spectroscopy (XPS) using the SCIENTA SES-100 spectrometer. For preparing the samples, the catalytic materials were dispersed in isopropanol at a concentration of 2 mg mL^_1 and deposited onto GC plates (1 .1 x1 .1 cm). The samples were tested with a non-monochromatic twin anode X-ray tube (XR3E2), where the characteristic energies were 1253.6 eV (Mg Ka1 ,2, FWHM 0.68 eV) and 1486.6 eV (Al Ka1 ,2, FWHM 0.83 eV). The pressure in the analysis chamber was below 10-9 Torr and the source power was 300 W. Survey spectra were obtained using the following parameters: energy range 800 to 0 eV, pass energy 200 eV, step size 0.5 eV. High resolution XPS scans were performed using pass energy 200 eV and step size 0.1 eV. An Ag wire attached to the sample holders was used for energy reference (Ag 3_d5/2 at 367.8 eV), no charging effects were observed. Peak fitting was done using CasaXPS (version 2.3.16) software.

TEM

Scanning transmission electron microscopy was done using Titan 200 (FEI) with 200 keV electron beam.

Electroanalytical studies

The electrochemical measurements were performed in a three-electrode glass cell, using a rotating disk electrode (RDE) setup and an Autolab potentiostat/galvanostat PGSTAT30 (Eco Chemie B.V.). High surface area Pt mesh served as a counter electrode. Potentials were measured against a reversible hydrogen electrode (RHE) connected to the cell through a Luggin capillary. Glassy carbon disks (geometric area of 0.126 cm²) polished to a mirror finish with 1 and 0.3 pm alumina slurries (Buehler) pressed into a Teflon holder served as working electrode.

Prior to modification, the GC electrode was sonicated in both isopropanol and Milli-Q water for 5 min to remove polishing residues. The catalyst suspension was homogenised by sonication for 30 min and 2.5 pL of the catalyst suspension was spin coated onto the GC electrode and allowed to dry in air, yielding the catalyst loading of 200 to 800 pg cm ².

Cyclic voltammograms (CVs) were recorded at a potential sweep rate (v) of 50 mV s^_1. The electrolyte solution was prepared using Milli-Q water, KOH pellets (p.a. quality, Merck); saturated with pure O2 (99.999%, AGA) and deaerated with Ar gas (99.999%, AGA). For comparison purpose experiments were also performed with commercial 20 wt% Pt/C (E-TEK) with loading of 200 pg cm^-2. The RDE technique was used to explore the electrocatalytic activity of the catalyst towards the ORR. The RDE polarisation curves were measured at different electrode rotation rates (w): 360, 610, 960, 1900, 3100 and 4600 rpm. Electrode rotation rate was controlled using a CTV101 speed control unit connected to an ED1101 rotator (Radiometer). The background currents were recorded at 10 mV s^_1 in argon-saturated 0.1 M KOH and were subtracted from the RDE data. Accelerated durability tests were also performed by cycling electrodes 2000 times in the potential range between 1 .0 and -0.2 V vs. RHE. RDE polarisation curves for O2 reduction were recorded before and after 2000 cycles and compared. All experiments were carried out at room temperature (23 ± 1 °C).

Results

X-ray diffraction (XRD) analysis confirmed that TAL-001 was crystalline (Figure 2), while the rest of materials were amorphous, except for TAL-003, for which no XRD was collected. The defined diffraction peaks for TAL-001 are located at 2Q = 15.1 °, 15.62°, 16.48°, 17.68°, 18.38°, 24,78°, 26.79°, 28.34° and 28.94°, revealing the high crystallinity of the product.

Surface composition of samples were examined by X-ray photoelectron spectroscopy (XPS). The XPS wide scan spectra of as-prepared TAL-001 and carbonised TAL-001 C@800 are depicted in Figures 3a and 4a respectively, where the presence of C, N, Fe, and O elements is indicated. The most distinctive XPS peak at 284.8 eV corresponds to C1 s, showing that before and after the heat-treatment catalyst is composed mostly of carbon. As a result of the pyrolysis process, most oxygen functionalities were removed and the oxygen content significantly decreased. Core-level XPS spectra in the Fe2p region presented in insets of Figures 3a and 4a confirm the presence of iron in the catalyst sample. The high-resolution N1 s XPS spectra were obtained to describe the nature of different nitrogen centres. Figures 3b and 4b show deconvoluted N1 s XPS spectra of as-prepared TAL-001 and heat-treated TAL-001 C@800 samples, where the presence of pyrrolic (400.7 eV), FeN_x (399.6 eV), oxidised (404.7 eV) and graphitic (402.6 eV) nitrogen moieties is confirmed. As can be seen from Figure 4b, after pyrolysis at 800 °C, the amount of pyrrolic nitrogen decreases, it is generally considered to have low electrocatalytic properties towards the ORR (Masa, 2015). The large amount of electrocatalytically active pyridinic nitrogen (398.0 eV) appears after the carbonisation step. Pyridinic and graphitic nitrogen moieties are known to be the most active for catalysing four-electron reduction of O2 in alkaline media (Masa, 2015; Niu, 2015). The percentage of FeN_x moieties slightly increased after pyrolysis. The XPS method allows only the surface of TAL-001 C@800 to be explored, but the catalyst presented in this work is highly porous and thus the elemental contents and types of nitrogen inside the TAL-001 C@800 structure may differ from the surface of the catalyst. The porous structure of materials is clearly seen from scanning electron micrographs (Figures 3c and 4c).

TEM images (Figure 5) of TAL-001 C@800 indicated formation of metal nanoparticles, which remain embedded into the network of MOF. Their formation may alter the physical properties of the catalytic material, however, microscopic features that affect electrocatalytic and chemical properties of the catalyst take place on its surface and cannot be directly visualised by TEM in detail.

Electrochemical behaviour of TAL-001 C@800 catalysts was analysed by cyclic voltammetry (CV) measurements in argon-saturated 0.1 M KOH solution at room temperature. We compared TAL- 001 C@800 performance against the state-of-the-art commercial 20 wt% Pt/C catalyst at equal loadings (200 pg cm^-2). Figure 6a shows that TAL-001 C@800 has high surface area. The TAL- 001 C@800 catalyst exhibited a symmetrical and rectangular CV without any characteristic redox features, as compared to Pt/C. The double-layer capacitance for TAL-001 C@800 is larger than that for Pt/C, showing that TAL-001 C@800 has high electrochemically accessible surface area. Increased specific surface area of the catalytic material is influential for mass activity enhancement for ORR electrocatalyst.

The RDE technique was employed to obtain insight into the ORR kinetics of the TAL-001 C@800 catalyst. The representative ORR polarisation curves for this electrocatalyst are shown in Figure 6b. Only the negative-going potential scans are presented and further analysed. Single-wave polarisation curves with well-defined reduction current plateaux were observed. RDE measurements revealed that oxygen reduction starts at the same onset potential as on the commercial Pt/C catalyst.

To further investigate the kinetics and reaction pathway of the catalysts during the ORR the corresponding Koutecky-Levich (K-L) plots at various electrode potentials were constructed from the RDE data. K-L plots show good linearity and parallelism (Figure 6c) which is typical for the first-order reaction kinetics with respect to the concentration of dissolved 0₂. The number of electrons transferred per O2 molecule (n) was calculated from the RDE data using the K-L equation (Bard, 2001 ). It was revealed that the TAL-001 C@800 catalysts follow the typical 4- electron transfer pathway in alkaline media (see inset to Figure 6c), indicating that oxygen is reduced fully to water on TAL-001 C@800 catalyst. Using the K-L analysis it is impossible to clarify whether this is a direct 4-electron reduction or 2+2 electron reduction via formation of peroxide intermediates. M/N/C catalysts are generally considered to reduce oxygen via the 2+2 electron pathway (Strickland, 2015), where both M-N_x sites and metal particles are responsible for O2 reduction in alkaline electrolyte. Metal-free nitrogen moieties present in TAL-001 C@800 may also be responsible for high ORR activity. It is also believed that Fe_xC_y improves the ORR catalytic activity by modulating the electronic structure of carbon (Hu, 2014). Figure 6d presents a comparison of the RDE results for TAL-001 C@800 and commercial Pt/C catalyst in 0.1 M KOH at a single electrode rotation rate. As can be seen, the ORR onset potential is the same for both electrocatalysts at the same loading. This indicates about a similar electrocatalytic activity of the TAL-001 C@800 material as compared to Pt/C in alkaline conditions.

As can be seen from Figure 6e, after being exposed to corrosive conditions TAL-001 C@800 electrocatalytic activity remained the same and TAL-001 C@800 revealed itself as a stable electrocatalyst for ORR. For the sake of comparison, durability tests were also performed for state-of-the-art Pt/C catalyst. In identical test conditions the £1/2 value decreased by 32 mV.

The catalytic materials obtained by carbonisation of TAL-001 at different temperatures (800, 900 and 1000 °C) were then compared (Figure 7). TAL-001 C@900 catalyst was the most optimal. The best performing system TAL-001 C@900 was then acid-leached, a procedure often used to remove inactive metal species that may obscure the performance, to afford catalytic material TAL-001 @900L.

The results obtained in this work suggest that the use of the TAL-001 C@900 catalyst offers excellent electrocatalytic behaviour towards the ORR, due possibly to the unique structure of the hybrid where N groups interconnect the Fe and C. The superior electrocatalytic properties and remarkable stability in electrochemical conditions makes TAL-001 C@900 an attractive electrocatalyst for ORR and a suitable cathode material for low-temperature fuel cells.

Although TAL-001 was electrochemically ineffective, with excessive metal leaching being observed (data not shown), its carbonisation at 800 and above °C (N2, 2 h) resulted in TAL- 001 C@X00 with insignificant mass loss. In our hands, the obtained TAL-001 C@900 catalyst specifically showed excellent performance in electrochemical tests. Catalysing oxygen electroreduction via 4-electron pathway, this particular TAL-001 C catalytic may be an excellent alternative for Pt/C based catalysts in fuel cell conditions.

Notably, the material obtained from the organic linker and iron(lll) chloride hexahydrate by means of having stirred at 140 °C for 2 h in DMF without any observed precipitate formation and upon the removal of solvent and follow-up carbonisation at 800 °C, was not effective in the ORR tests. Hence, the formation of MOF, which is typically observed by a formation of a solid precipitate, may be a prerequisite for fabrication of an active catalytic material. Example 4 - Variation of metal/organic ratios on Fe(lll) 1H-benzo[cf]imidazole-5,6-diol catalyst precursor composition

Following method described in Example 1 , catalyst precursor was prepared using a range of starting metal/organic (M/L) molar ratios. The carbon, hydrogen and nitrogen content (wt%) was measured by chemical analysis to show that the final product has a ca. 1 :1 ratio. On this basis, the metal/organic molar ratio did not alter the chemical composition of the final material obtained.

Resulting catalyst precursors were characterised by HR-SEM and additionally XRD.

Example 5 - Preparation and characterisation of various metal 1H-benzo[cf]imidazole-5,6- diol derived catalytic materials and carbonisation of Fe(lll) 1 H-benzo[d]imidazole-5,6-diol catalyst precursor under varying conditions

(i) Preparation of catalyst precursors

Fe-MOF (TAL-001)

FeCl3 6H20 (90 mg, 0.333 mmol, 1 .0 equiv) and 1 H-benzo/c//imidazole-5,6-diol (100 mg, 0.666 mmol, 2.0 equiv) were dissolved in a mixture of DMF/water (1.5 mL/1.5 ml_), and the mixture left to react at 100 °C. After 3 days, the mixture was cooled to room temperature, centrifuged, washed with DMF (3x5 ml_), and dried (1 10 °C, 16 h) to give a black solid (48 mg).

Co-MOF (TAL-002)

A solution of CoCh-ehhO (3.98 g, 16.7 mmol, 1 .0 equiv) and 1 /-/-benzo[c/]imidazole-5,6-diol (5.02 mg, 33.5 mmol, 2.0 equiv) in DMF/water (15 mL/15 mL) was left to stir at 85 °C. After 72 h, the mixture was cooled down to RT, centrifuged, the precipitate was washed with DMF (3x) and dried (1 10 °C, 16 h) to give the desired material as a black solid (2.614 g).

Cu-MOF (TAL-003)

A solution of CuCh^FhO (2.66 g, 15.6 mmol, 1 .0 equiv) and 1 /-/-benzo[c/]imidazole-5,6-diol (4.68 g, 31.2 mmol, 2.0 equiv) in DMF/water (15 mL/15 mL) was left to stir at 85 °C. After 72 h, the mixture was cooled down to RT, centrifuged, the precipitate was washed with DMF (3x) and dried (1 10 °C, 16 h) to give the desired material as a black solid (1.843 g).

Mn-MOF (TAL-004)

A solution of MnCI₂-4H₂0 (200 mg, 1.01 mmol, 1.0 equiv) and 1 /-/-benzo[c/]imidazole-5,6-diol (455 mg, 3.03 mmol, 3.0 equiv) in DMF/water (5 ml_/5 ml.) was left to stir at 85 °C. After 72 h, the mixture was cooled down to RT, centrifuged, the precipitate was washed with DMF (3*), and dried (1 10 °C, 16 h) to give the desired material as a black solid (33.2 mg).

Ni-MOF (TAL-005)

A solution of NiCI₂-6H₂0 (200 mg, 0.841 mmol, 1 .0 equiv) and 1 /-/-benzo[c/]imidazole-5,6-diol (378 mg, 2.52 mmol, 3.0 equiv) in DMF/water (5 mL/5 ml.) was left to stir at 100 °C. After 72 h, the mixture was cooled down to RT, centrifuged, the precipitate was washed with DMF (3x10 ml_), and dried (1 10 °C, 16 h) to give the desired material as a black solid (39 mg).

(ii) Carbonisation

Carbonisation was undertaken at 800 °C (N₂, rapid heat, 2 h rapid cooling) to provided TAL- 001 C@800, TAL-002C@800, TAL-003C@800, TAL-004C@800 and TAL-005C@800. For TAL- 001 , carbonisations at 900 °C (TAL-001 C@900) and 1000 °C (TAL-001 C@1000) were also performed.

(iii) Acid leaching

TAL-001 was carbonized under N₂ at 900 °C for 2 h, removed from heating zone, and suspended in a 1 :1 mixture of 0.5 M H₂S0₄ and 0.5 M HNO3, stirred for 8 h at room temperature, filtered, and re-carbonised under N₂ at 900 °C for 2 h to give the acid leached material TAL-001 C@900L.

(iv) Results

The data in Figure 7a to Figure 7d demonstrate that carbonisation at 900 and 1000 °C is more preferential in establishing better performing catalytic material than that at 800 °C.

The performance of acid leached material TAL-001 C@900L is shown in Figures 7e and 7f. The acid-leaching procedure used with TAL-001 @C900 in order to remove iron based smaller particles smooths out the output curves, and suggests that this or simplified acid-leaching procedure without double carbonisation treatment, may be helpful in providing a stable, high quality TAL-001 -based ORR catalyst. The data in Figure 8 demonstrate that structurally by HRSEM it is impossible to dissect between crystalline and amorphous precursor and their carbonised at 800 °C materials do not drastically differ on their structural basis. However, certain mass detection properties in TAL-002 (cobalt) case may indicate to formation of cobalt nanoclusters/nanoparticles at the interface. This is not the case for the rest of the TAL catalyst series.

The data in Figure 9 demonstrate performance of various earth abundant transition metal based catalyst precursors, which were all carbonised at 800 °C for 2 h. The iron-based systems (e.g. TAL-001 C@800) are by far the best performing ones, while manganese-based ones being the worst (TAL-005C@800). Both cobalt (TAL-002C@800) and copper (TAL-003C@800) systems display similar onset and halfwave potential values.

Example 6 - Chemical catalysis

Catalytic material prepared as described previously was used in a range of chemical reactions as follows:

, ,

[copper]

in the presence of no formation of Ph-Ph [Suzuki coupling]

1 equiv of PhB(OH)₂ no formation of PhNH-4-An [Chan-Lam coupling]

A mixture of p-anisidine (101 mg, 0.820 mmol), benzeneboronic acid (100 mg, 0.820 mmol), and TAL-003C@800 (5 mg, 5 wt%) in MeOH (2 ml.) was left to stir at RT. After 16 h, the mixture was concentrated under reduced pressure and purified by flash chromatography (PE/EtOAc) to give the desired compound as a yellow solid (18.2 mg, 0.1 19 mmol, 15%).

¹H NMR (400 MHz, CDCIs) d 7.89 (d, 2H, J = 8.7), 7.00 (d, 2H, J = 8.7), 3.89 (s, 3H). B(OH)₂

cat. TAL-003C@800

MeOH, 16 h, 80 °C

[copper]

in the presence of no formation of PhOPh [Chan-Lam coupling] 1 equiv of PhOH no formation of PhH

A mixture of benzeneboronic acid (50.0 mg, 0.410 mmol), phenol (38.6 mg, 0.410 mmol) and TAL-003C@800 (5 mg, 10 wt%) in MeOH (2 ml.) was left to stir at 80 °C. After 16 h, the mixture was cooled down to RT, filtered through a Celite pad, concentrated under reduced pressure and purified by flash chromatography (PE/EtOAc) to give the desired product as a colourless solid (10.0 mg, 0.0648 mmol, 32%).

¹H NMR (400 MHz, CDCIs) d 7.61-7.59 (m, 4H), 7.47-7.43 (m, 4H), 7.37-7.33 (m, 2H). ¹³C NMR (100 MHz, CDCI3) d 141.4, 128.9, 127.4, 127.3.

aq. - u , ,

[iron]

A mixture of TBHP (70% aq soln, 74 mI_, 0.54 mmol, 3.0 equiv), diphenylmethane (30.0 mg, 0.18 mmol, 1 .0 equiv) and TAL-001 C@800 (3 wt%) was left to stir at 80 °C. After 24 h, the mixture was filtered through a silica gel pad using CH2CI2, the organic phase was extracted, concentrated under reduced pressure to give the desired product as a colourless solid (quant yield).

¹H NMR (400 MHz, CDCI₃) d 7.82-7.79 (m, 4H), 7.61-7.57 (m, 2H), 7.48 (t, 4H, J = 7.6).

¹³C NMR (100 MHz, CDCI3) d 196.9, 137.7, 132.5, 130.2, 128.4.

[iron]

A mixture of TBHP (70% aq soln, 1.56 mL, 1 1 .3 mmol, 12.0 equiv), m-xylene (100 mg, 0.942 mmol, 1 .0 equiv) and TAL-001 C@800 (1 wt%) was left to stir at 80 °C. After 24 h, the mixture was filtered through a silica gel pad using MeOH, concentrated under reduced pressure and purified by flash chromatography (PE/EtOAc) to give a separated mixture of the desired products: 3-methylbenzoic acid (26.7 mg, 0.196 mmol, 21 %) and isophthalic acid (42.0 mg, 0.253 mmol, 27%).

3-Methylbenzoic acid:

¹H NMR (400 MHz, DMSO-de) d 12.86 (s, 1 H), 7.76-7.73 (m, 2H), 7.43-7.35 (m, 2H), 2.35 (s, 3H).

¹³C NMR (100 MHz, DMSO-de) d 167.4, 137.9, 133.5, 130.7, 129.8, 128.5, 126.5, 20.8.

Isophthalic acid:

¹H NMR (400 MHz, DMSO-de) d 13.2 (s, 2H), 8.48 (s, 1 H), 8.17 (d, 1 H, J = 1.6), 8.15 (d, 1 H, J = 1 .6), 7.64 (t, 1 H, J = 7.7).

¹³C NMR (100 MHz, DMSO-de) d: 166.6, 133.4, 131.2, 130.0, 129.2.

A mixture of TBHP (70% aq soln, 196 pL, 1.41 mmol, 3.0 equiv), toluene (50 pL, 0.47 mmol, 1 .0 equiv) and TAL-001 C@800 (3 wt%) was left to stir at 80 °C. After 24 h, the mixture was filtered through a silica gel pad using MeOH, concentrated under reduced pressure, and re-dissolved in a K₂CO₃ aq soln (10 mL) was added, washed with DCM (2x10 mL), acidified with cone HCI, extracted with DCM (3x10 mL), dried over MgS0₄, concentrated under reduced pressure to give the desired product as a colourless solid (20 mg, 0.16 mmol, 35%).

¹H NMR (400 MHz, CDCIs) d 8.13 (d, 2H, J = 7.1 ), 7.63 (t, 1 H, J = 7.4), 7.49 (t, 2H, J = 7.7).

¹³C NMR (100 MHz, CDCI3) d 172.0, 134.0, 130.4, 129.4, 128.7

A mixture of ethylbenzene (348.8 pL, 2.83 mmol) and TAL-002C@800 (30 mg, 10 wt%) was left to stir (open to air) at 100 °C. After 16 h, the mixture was filtered through a Celite pad, concentrated under reduced pressure and purified by flash chromatography (PE/EtOAc) to give the desired compound as a colourless oil (62.9 g, 0.524 mmol, 19%).

¹H NMR (400 MHz, CDCI₃) d 7.96-7.93 (m, 2H), 7.57-7.53 (m, 1 H), 7.47-7.43 (m, 2H), 2.59 (s, 3H).

¹³C NMR (100 MHz, CDCI3) d 198.2, 137.2, 133.2, 128.6, 128.4, 26.7.

Example 7 - Comparison of 1H-benzo[cf]imidazole-5,6-diol linker with related structures

(i) Preparation of 1 H-Benzorc/limidazole-5,6-dicarboxylic acid HC0₂H KMn0₄ ^HOOCs/^N

— 100 °C 'Ti > — 70 °C - HOOC Y ^T N

H ^H

5, 6-Dimethyl- 1 H-benzo[d]imidazole

A solution of 4, 5-dimethylbenzene-1 ,2-diamine (2.024 g, 14.860 mmol, 1.0 equiv) in formic acid

(10 mL) was left to stir at 100 °C. After 4 h, the mixture was concentrated under reduced pressure, water added, the solution was basified with solid K₂CO₃, and the precipitate was collected, washed with water and dried to give the desired product as a colourless solid (1 .813 g, 12.402 mmol, 83%).

¹H NMR (400 MHz, DMSO-de) d 12.18 (br s, 1 H), 8.05 (s, 1 H), 7.34 (s, 2H), 2.30 (s, 6H).

¹³C NMR (100 MHz, DMSO-de) d 141 .0, 130.1 , 20.0. (two carbons not observed)

1H-Benzo[d]imidazole-5,6-dicarboxylic acid (L2)

A solution of KMn0₄ (19.594 g, 124.0 mmol, 10 equiv) was added dropwise into a solution of 5,6- dimethyl-1 /-/-benzo[c/]imidazole (1.813 g, 12.40 mmol, 1.0 equiv) in water/f-BuOH (16 mL/16 mL), the mixture was left to stir gradually heating up to 70 °C. After addition, heating was turned off, the mixture was left to stir at RT for 15 min, after which Na2SC>3 (4.765 g, 37.81 mmol, 3.0 equiv) was added, the mixture was then left to stir at 80 °C. After 30 min, the mixture was filtered, washed with boiling water, filtrate was concentrated under reduced procedure to approximately 50 ml_, diluted with water, cooled down to 0 °C, acetic acid/water (18 mL/9 ml.) added, precipitate was collected, washed with DMF, filter again, concentrated under reduced pressure, dried to give the desired product as a colourless solid (71 1.2 mg, 3.450 mmol, 28%).

¹H NMR (400 MHz, DMSO-de) d 8.70 (s, 1 H), 8.26 (s, 2H).

¹³C NMR (100 MHz, DMSO-de) d 163.4, 124.1 . (three carbons not observed)

(ii) Preparation of catalyst precursors Fe-COOH-MOF (TAL-006)

A solution of FeCl₃-6H₂0 (440 mg, 1 .629 mmol, 1 .0 equiv) and 1 /-/-benzo[c/]imidazole-5,6- dicarboxylic acid (671 mg, 3.255 mmol, 2.0 equiv) in DMF/water (3 ml_/3 ml.) was left to stir at 100 °C. After 72 h, the mixture was cooled down to RT, centrifuged, the precipitate was washed with DMF (3x10 ml_), and dried to give the desired material as a yellow solid (593 mg).

Fe-OMe-MOF (TAL-007)

A solution of FeCl₃-6H₂0 (758 mg, 2.804 mmol, 1 .0 equiv) and 5,6-dimethoxy-1 /-/- benzo[c/]imidazole (1 .00 g, 5.610 mmol, 2.0 equiv) in DMF/water (3 ml_/3 ml.) was left to stir at 100 °C. After 72 h, the mixture was cooled down to RT, centrifuged, the precipitate was washed with DMF (3x10 ml_), and dried to give the desired material as a red solid (599 mg).

(iii) Carbonisation

Carbonisation was undertaken at 800 °C (N2, rapid heat, 2 h rapid cooling) to give final catalytic materials TAL-006C@800 and TAL-007C@800.

(iv) Results

The obtained catalytic materials TAL-006C@800 and TAL-007C@800 were then compared with TAL-001 C@800 under ORR conditions. The results are summarised in Figure 10. Dicarboxylic acid analogue TAL-006C@800 had reduced activity, while the performance of methyl protected version TAL-007C@800 was rather poor. Both TAL-006C@800 and TAL-007C@800 were much less active than TAL-001 C@800.

Example 8 - Preparation of additional benzoimidazole linkers

L4 1 H-benzo[d]imidazole-5, 6-diamine

1 H-Benzo[d]imidazole

A mixture of o-phenylenediamine (15.00 g, 0.139 mol) and formic acid (100 ml.) was left to stir at 100 °C. After 16 h, it was concentrated under reduced pressure, redissolved in water (200 ml_), basified with K₂CO₃ and filtered to give the desired compound as a colorless solid (15.26 g, 0.130 mol, 94%).

¹H NMR (CD₃OD, 400 MHz) d 8.14 (s, 1 H), 7.62-7.58 (m, 2H), 7.27-7.23 (m 2H)

1³C NMR (CD₃OD, 100 MHz) d 142.4, 123.8, 1 16.1.

5.6-Dinitro-1 H-benzo[d]imidazole

KNO₃ (1.07 g, 10.58 mmol, 2.5 equiv.) was added to a solution of 1 /-/-benzo[c/]imidazole (500 mg, 4.23 mmol, 1.0 equiv.) in cone. H₂SO₄ (2 ml.) at 0 °C and the mixture was left to stir at 50 °C. After 1 h, additional KNO₃ (2.14 g, 21 .16 mmol, 5.0 equiv.) and cone. H₂SO₄ (2 ml.) were added and the mixture was left to stir at 1 10 °C. After 8 h, crushed ice was added, the formed precipitate was collected by filtration and purified by flash chromatography (DCM/MeOH, 100:1 ) to give the desired compound as a light yellow solid (373.4 mg, 1.79 mmol, 42%).

¹H NMR (DMSO-de, 400 MHz) d 8.77 (s, 1 H), 8.49 (s, 2H).

¹³C NMR (DMSO-de, 100 MHz) d 140.4, 131.3, 130.7, 105.0.

1 H-Benzo[d]imidazole-5, 6-diamine

Hydrazine monohydrate (3.1 ml_, 63.74 mmol, 1 1.2 equiv) was added dropwise to a solution of

5.6-dinitro-1 H-benzo[c/]imidazole (1 .179 g, 5.66 mmol, 1 .0 equiv) and Pd/C (10 wt%, 0.12 g) in anhydrous EtOH (20 ml.) at 0 °C and the mixture was left to stir at 80 °C. After 30 min, it was filtered through silica gel, and concentrated under reduced pressure to give the desired compound as a colorless solid (0.837 g, 5.65 mmol, quant). ¹H NMR (DMSO-de, 400 MHz) d 7.67 (s, 1 H), 6.71 (s, 2H), 4.28 (br s, 4H).

¹³C NMR (DMSO -cfe, 100 MHz) d 137.6, 132.9, two carbons were not observed.

L5 5-Fluoro-1 H-benzo[cf]imidazole-6-ol

W-(3,4-Difluorophenyl)acetamide

Hydrazine monohydrate (7.65 ml_, 0.153 mol, 1 1.2 equiv) was added dropwise to a solution of 1 ,2-difluoro-4-nitrobenzene (2.17 g, 13.64 mmol, 1.0 equiv) and Pd/C (5 wt%, 0.108 g) in anhydrous EtOH (25 ml.) at 0 °C and the mixture was left to stir at 80 °C. After 30 min, it was filtered through silica gel concentrated, redissolved in DCM (100 ml_), washed with water (3x20 ml_), dried over MgS0₄, and concentrated to 50 ml_. Ac₂0 (1.93 ml_, 20.46 mmol, 1.5 equiv) and Et₃N (2.85 ml_, 20.46 mmol, 1 .5 equiv) were added at 0 °C to this solution and the mixture was left to stir at RT. After 1 h, it was concentrated, redissolved in CHCI₃ (100 ml_), washed with 1 M HCI (30 ml_), sat. NaHC0₃ solution (30 ml.) and brine (30 ml_), dried over Na₂S0₄ and concentrated to give the desired product as a colourless solid (1.79 g, 10.46 mmol, 77%).

¹H NMR (CDCI₃, 400 MHz) d 7.62-7.56 (m, 1 H), 7.52 (br s, 1 H), 7.1 1-6.98 (m, 1 H), 2.16 (s, 3H). ¹³C NMR (CDCI₃, 100 MHz) d 168.6, 150.2 (JCF = 246.0), 147.3 (JCF = 271.0), 134.5 (JCF = 1 1.8), 1 17.3 (JCF = 18.0), 1 15.6, 109.9 (JCF = 21 .6).

W-(4,5-Difluoro-2-nitrophenyl)acetamide

KN0₃ (1 .71 g, 16.97 mmol, 1.2 equiv.) was added into a solution of N-( 3,4- difluorophenyl)acetamide (2.42, 14.14 mmol, 1.0 equiv.) in cone. H₂S0₄ (8 ml.) on at 0 °C and the mixture was left to stir at 0 °C. After 3 h, ice was added, the formed precipitate was collected by filtration and washed with water to give the desired compound as a light yellow solid (2.43 g, 1 1.24 mmol, 80%).

¹H NMR (CDCIs, 400 MHz) d 10.45 (br s, 1 H), 8.84 (dd, 1 H, J = 12.8, 7.6), 8.12 (dd, 1 H, J = 10.1 , 8.0), 2.31 (s, 3H).

¹³C NMR (CDCIs, 100 MHz) d 169.2, 133.2, 1 15.0 (JCF = 25.4), 1 10.8 (JCF = 25.1 ), 25.8, two carbons were not observed.

5-Amino-2-fluoro-4-nitrophenol

A solution of /V-(4,5-difluoro-2-nitrophenyl)acetamide (2.43 g, 1 1.24 mmol, 1 .0 equiv) in 10% aq. NaOH (25 ml.) was left to stir at 80 °C. After 16 h, it was allowed to cool to RT, acidified with cone. HCI, filtered, and washed with water to give the desired compound as a yellow solid (1.90 g, 1 1.04 mmol, 98%).

¹H NMR (DMSO-de, 400 MHz) d 1 1.32 (br s, 1 H, OH), 7.71 (d, 1 H, J = 1 1.7), 7.42 (br s, 2H), 6.47 (d, 1 H, J = 4.9).

¹³C NMR (CDsOD, 100 MHz) d 155.2, 147.0, 146.1 , 143.7, 1 12.6 (J_CF = 23.2), 104.2.

4-Fluoro-5-methoxy-2-nitroaniline

A mixture of Mel (0.72 ml_, 1 1 .62 mmol, 2.0 equiv), 5-amino-2-fluoro-4-nitrophenol (1 .00 g, 5.81 mmol, 1.0 equiv) and K2CO₃ (1.20 g, 8.71 mmol, 1 .5 equiv) in MeCN (10 ml.) was left to stir at 70 °C. After 16 h, it was filtered, concentrated, redissolved in DCM, washed with water (3x30 ml_), dried over Na₂S0₄ and concentrated to give the desired compound as a yellow solid (420 mg, 2.26 mmol, 39%).

¹H NMR (CDCI₃, 400 MHz) 6 7.86 (d, 1 H, J = 1 1.6), 6.20 (d, 1 H, J = 7.2), 6.17 (br s, 2H), 3.92 (s, 3H).

¹³C NMR (CDCI3, 100 MHz) 6 155.3, 149.9, 143.8, 143.0, 1 12.5 (J_CF = 22.8), 99.9, 56.5.

5-Fluoro-6-methoxy-1H-benzo[cf]imidazole

Hydrazine monohydrate (1.3 ml_, 25.27 mmol, 10 equiv) was added dropwise to a solution of 4- fluoro-5-methoxy-2-nitroaniline (420 mg, 2.26 mmol, 1 .0 equiv) and Pd/C (5 wt%, 21 mg) in anhydrous EtOH (20 ml.) at 0 °C and the mixture was left to stir at 80 °C. After 90 min, it was filtered through silica gel, concentrated, redissolved in formic acid (30 ml.) and was left to stir at 100 °C. After 16 h, the mixture was concentrated, redissolved in water (50 ml_), basified with K2CO₃ and extracted with DCM (3x10 ml.) to give the desired compound as a light yellow solid (255.8 mg, 1 .54 mmol, 68%).

¹H NMR (CD₃OD, 400 MHz) 6 8.07 (s, 1 H), 7.32 (d, 1 H, J = 1 1.1 ), 7.24 (d, 1 H, J = 7.4), 3.91 (s, 3H).

¹³C NMR (CD₃OD, 100 MHz) 6 153.1 , 150.7, 147.0, 142.5, 57.1 , two carbons were not observed.

5-Fluoro-1H-benzo[cf]imidazole-6-ol

A solution of 5-fluoro-6-methoxy-1 /-/-benzo[c/]imidazole (230 mg, 1 .38 mmol, 1 .0 equiv) in 48% aq. HBr (10 ml.) was left to stir at 120 °C. After 4 h, the mixture was cooled down to RT, extracted with DCM (3x10 ml.) and EtOAc (3x10 ml.) to give the desired compound as a red solid (206.9 mg, 1 .36 mmol, quant).

¹H NMR (CD₃OD, 400 MHz) 6 9.22 (s, 1 H), 7.60 (d, 1 H, J = 9.9), 7.31 (d, 1 H, J = 7.4).

¹³C NMR (CD₃OD, 100 MHz) 6 153.4 (J_CF = 236.9), 147.6, 140.3, 128.7, 124.6, 102.2 (J_CF = 25.6), 101 .7 (J_CF = 3.4).

L6 2-Methyl-1 H-benzo[cf]imidazole-5,6-diol

5, 6-Dimethoxy-2 -methyl-1 H-benzo[cf]imidazole

Hydrazine monohydrate (7.6 mL, 152.7 mmol, 10 equiv) was added dropwise to a solution of 1 ,2- dimethoxy-4, 5-dinitrobenzene (3.5 g, 15.3 mmol, 1.0 equiv) and Pd/C (10%, 0.35 g) in anhydrous EtOH (40 mL) at 0 °C and the mixture was left to stir at 80 °C. After 30 min, it was filtered through silica gel, concentrated, redissolved in acetic acid (15 mL) and left to stir at 100 °C. After 16 h, the mixture was concentrated, redissolved in water (50 mL), basified with K2CO₃, extracted with DCM (3x50 mL) and purified by flash chromatography (EtOAc/DCM, 1 :1 ) to give the desired compound as a colorless solid (0.992 g, 5.16 mmol, 34%).

¹H NMR (CDCI₃, 400 MHz) d 7.04 (s, 2H), 3.91 (s, 6H), 2.58 (s, 3H).

¹³C NMR (CDCI3, 100 MHz) d 149.1 , 147.0, 131 .3, 97.3, 56.5, 14.7.

2 -Methyl-1 H-benzo[cf|imidazole-5,6-diol

A solution of 5,6-dimethoxy-2-methyl-1 /-/-benzo[c/]imidazole (0.992 g, 5.16 mmol, 1 .0 equiv) in 48% aq. HBr (30 mL) was left to stir at 120 °C. After 4 h, the mixture was cooled down to 0 °C, filtered and the precipitate washed with petroleum ether to give the desired compound as a brown solid (843.8 mg, 5.14 mmol, quant).

¹H NMR (DMSO-de, 400 MHz) d 7.09 (s, 2H), 2.72 (s, 3H).

¹³C NMR (DMSO-de, 100 MHz) d 147.3, 145.5, 123.7, 98.2, 12.1.

L7 2-(Trifluoromethyl)-1H-benzo[cf]imidazole-5,6-diol

5,6-Dimethoxy-2-(trifluoromethyl)-1H-benzo[c/]imidazole

Hydrazine monohydrate (7.6 mL, 152.7 mmol, 10 equiv) was added dropwise to a solution of 1 ,2- dimethoxy-4, 5-dinitrobenzene (3.5 g, 15.3 mmol, 1.0 equiv) and Pd/C (10%, 0.35 g) in anhydrous EtOH (40 mL) at 0 °C and the mixture was left to stir at 80 °C. After 30 min, the mixture was filtered through silica gel, concentrated, redissolved in trifluoroacetic acid (15 mL) and the mixture was left to stir at 72 °C. After 16 h, it was concentrated, redissolved in water (50 mL), basified with K2CO₃, extracted with DCM (3x50 mL) and purified by flash chromatography (EtOAc/DCM, 1 :1 ) to give the desired product (2.86 g, 1 1 .62 mmol, 76%).

¹H NMR (CDCI3, 400 MHz) d 7.14 (s, 2H), 3.92 (s, 6H).

¹³C NMR (CDCI₃, 100 MHz) d 149.5, 138.2 (JCF = 41 ), 130.7, 1 18.6 (JCF = 268), 97.5, 56.4.

2-(Trifluoromethyl)-1H-benzo[cf]imidazole-5,6-diol A solution of 5,6-dimethoxy-2-(trifluoromethyl)-1 /-/-benzo[c/]imidazole (2.86 g, 1 1.62 mmol, 1 .0 equiv) in 48% aq. HBr (50 ml.) was left to stir at 120 °C. After 4 h, the mixture was cooled down to 0 °C, filtered and the precipitate was washed with petroleum ether to give the desired compound as a colorless solid (2.53 g, 1 1.6 mmol, quant).

¹H NMR (CDsOD, 400 MHz) d 7.13 (s, 2H).

¹³C NMR (CDsOD, 100 MHz) d 150.0, 134.9 (JCF = 47.8), 127.5, 1 18.4 (JCF = 269), 99.1 .

L8 2,2’-(1 ,4-Phenylene)bis(1 H-benzo[cf]imidazole-5,6-diol)

1 ,4-Bis(5,6-dimethoxy-1 H-benzo[d]imidazole-2-yl)benzene

A mixture of terephthalic acid (1 .51 g, 9.06 mmol, 1.0 equiv), 4,5-dimethoxybenzene-1 ,2-diamine (3.20 g, 19.02 mmol, 2.1 equiv) in titanium isopropoxide (20 ml.) was left to stir at 150 °C. After 16 h, it was filtered, washed with methanol and dried to give the desired product as a light brown solid (2.02 g, 4.69 mmol, 52%).

¹H NMR (DMSO-de, 400 MHz) d 12.74 (br s, 2H), 8.22 (s, 4H), 7.23 (s, 2H), 7.03 (s, 2H), 3.83 (s, 12H).

¹³C N MR (DMSO-C/₆, 100 MHz, rotamers are observed) 6 149.1 , 147.2/146.5, 137.6, 130.8, 126.2, 101 .6/94.3, 55.9.

2,2’-(1 ,4-Phenylene)bis(1 H-benzo[d]imidazole-5,6-diol)

A solution of 1 ,4-bis(5,6-dimethoxy-1 /-/-benzo[c/]imidazole-2-yl)benzene (1 .10 g, 2.56 mmol, 1 .0 equiv) in 48% aq. HBr (30 ml.) and was left to stir at 120 °C. After 48 h, it was cooled down to 0 °C, filtered, and the precipitate was washed with MeOH (10x50 ml.) give the desired compound as a green solid (0.623 g, 1 .66 mmol, 65%).

¹H NMR (DMSO-de, 400 MHz) d 8.35 (s, 4H), 7.16 (s, 4H).

¹³C NMR (CDsOD, 100 MHz) d 149.2, 129.4, 129.3, 98.8, one carbon not observed.

L9 1 ,4-Bis(5,6-dimethyl-1 H-benzo[d]imidazole-2-yl)benzene

Terephthalic acid (1 .74 g, 10.47 mmol, 1 .0 equiv) was added into a mixture of 4,5- dimethylbenzene-1 ,2-diamine (3.00 g, 22.03 mmol, 2.1 equiv) in titanium isopropoxide (20 ml_), the mixture was left to stir at 150 °C. After 16 h, the mixture was filtered, washed with MeOH, and dried to give the desired product as a light yellow solid (2.82 g, 7.69 mmol, 73%).

¹H NMR (DMSO-de, 400 MHz) d 8.27 (s, 4H), 7.38 (s, 4H), 2.33 (s, 12H).

¹³C NMR (DMSO-C/₆, 100 MHz) d 150.0, 131.2, 130.8, 127.2, 126.6, 1 15.3, 20.1.

Example 9 - Preparation of further TAL precursors derived from additional

benzoimidazole linkers and metal centres

Conditions A: A mixture of a metal salt (1.0 equiv) was added slowly into a solution of ligand (2.0 equiv) in DMF/water (1 :1 ) was left to stir at 100 °C. After 72 h, it was cooled down to RT, centrifuged, washed with DMF (3x) and dried to give the desired material.

Conditions B: A mixture of a metal salt (1.0 equiv) was added slowly into a solution of ligand (2.0 equiv) in 30% aq. NHs/DMF/EtOH/water (4:10:10:15) was left to stir at RT. After 24 h, it was filtered, washed with EtOH and dried to give the desired material.

The results are summarised below:

*As prepared according to Example 5 or Example 7. Metal salt used: [Fe] = FeCl36H₂0; [Co] = C0CI₂6H₂O; [Cu] = CUCI₂2H₂0; [Mn] = MnCI₂4H₂0; [Ni] = N1CI26H2O; [Zn] = ZnCI₂.

Example 10 - Preparation of additional TAL catalysts General procedure

TAL-X MOF-type materials were carbonized at an indicated temperature of 800, 900 or 1000 °C under N₂ for 2 h (rapid heat, slow cooling). Carbonized materials were suspended in a 1 :1 mixture of 0.5 M H2SO4 and 0.5 M HNO3, stirred for 8 h at 50 °C, filtered, and recarbonized under N₂ at the same temperature (2 h) to give materials TAL-XC@XXX, where XXX indicates the temperature of carbonization. The acid leached materials are denoted with an additional‘L’. Acid leached materials TAL-001 C@900L, TAL-006C@900L and TAL-001 C@900L by characterized by HRTEM, XRD and XPS (Figure 11 ) as described in Example 3.

Electroanalytical methods

Electrochemical measurements, including ORR, HER and OER tests were performed in a three- electrode glass cell, using a rotating disk electrode (RDE) setup and an Autolab potentiostat/galvanostat PGSTAT30 (Eco Chemie B.V.). A glassy carbon (GC) rod served as counter electrode. Potentials were measured against a reversible hydrogen electrode (RHE) connected to the cell through a Luggin capillary. GC disks (geometric area of 0.126 cm²) polished to a mirror finish with 1 and 0.3 pm alumina slurries (Buehler) pressed into a Teflon holder served as working electrodes.

Prior to modification, the GC electrode was sonicated in both isopropanol and Milli-Q water for 5 min to remove polishing residues. The catalyst suspension was homogenized by sonication for 30 min and catalyst suspension was spin-coated onto the GC electrode and allowed to dry in air, yielding the catalyst loading of 800 (non-leached materials) and 500 (acid leached materials) pg cm^-2. The electrolyte solution was prepared using Milli-Q water, KOH pellets (p.a. quality, Merck) or H₂SO₄ (Suprapur, Merck); saturated with pure O₂ (99.999%, AGA) and deaerated with Ar gas (99.999%, AGA). Comparison experiments were performed with 20 wt% Pt/C (E-TEK; loading of 100 pgPt cm^-2) and 99.9% RUO₂ (Alfa Aesar; loading of 120 pg cm^-2).

The RDE technique was used to explore the electrocatalytic activity of the catalysts towards the ORR. Cyclic voltammograms were recorded at a potential sweep rate (v) of 50 mV s^-1 in Ar- saturated solution in the potential range of -0.1 ÷1.4 V. The RDE polarization curves were measured in 0₂-saturated electrolyte solution at a scan rate of 10 mV s^-1 in the potential range of -0.1 ÷1.1 V at different electrode rotation rates (w): 360-4600 rpm. Electrode rotation rate was controlled using a CTV101 speed control unit connected to an ED1101 rotator (Radiometer). Background currents (not shown) were measured in Ar-saturated solution at a scan rate 10 mV s^-1 in the potential range of -0.1 ÷1.1 V. The background correction was made by subtracting background currents from the RDE data. The data was normalized to the geometric area of the GC electrode. The ORR and OER data were automatically corrected for iR drop using Nova software. HER curves were obtained in 0.1 M KOH at 1600 rpm in the potential range of -0.8÷1 V potential range at a scan rate of 10 mV s^-1.

Accelerated durability tests were performed by cycling electrodes 5000 times in the potential range between 0.6 and 1 V vs. RHE (ORR) and between 1 .0 and 1 .8 V vs. RHE (OER), using a scan rate of 100 mV s^-1. RDE polarization curves for ORR and OER were recorded before and after 5000 cycles and compared. All experiments were carried out at room temperature (23 ± 1 °C).

The results are summarised below:

The catalytic sites in the leached materials are more readily characterized, and typically, perform better as there are no additional oxides and nanoparticles at the surface of the catalyst material (Figure 1 1 ). All the following chemical and electrochemical examples are based on acid leached materials. Different ligands do in fact influence the performance in ORR, OER and HER as shown in Figures 12-13. Moreover, bimetallic systems also function differently (Figure 14).

Partial characterization of selected final materials by MP-AES

MP-AES. Analytical samples were digested in Anton Paar Multiwave PRO microwave digestion system using NXF100 vessels (PTFE/TFM liner) in 8NXF100 rotor. TAL-00XC@-X00L samples (10 mg) were dissolved in 69% HNC>₃ (4 ml.) and H₂0₂ (2 ml_), then 48% HF (0.1 ml.) was added, the vessels were capped and digested in the microwave unit. After digestion, the samples were diluted using 2% HNO₃ to a final dilution factor of 61 ,000 and analyzed using Agilent 4210 MP- AES. Fe and Lu (an internal standard added online via a T-shaped micro-mixer) were measured at 371.993 and 547.669 nm, respectively. Example 11 - Utility of TAL-X systems in the catalytic oxidation of alkylarenes

General Procedure

A mixture of substrate, 70% aq. TBHP (3-18 equiv) and catalyst (5 or 10 mg/mmol of substrate) were left to stir at 80 °C. After indicated time (16 or 24 h), the samples were prepared for crude NMR yield assessment or were worked up to obtain isolated yield. Workup 1: The mixture was filtered through a Celite or silica gel pad using MeOH, concentrated and purified by flash chromatography to give the desired compound.

Workup 2: The mixture was filtered through a Celite or silica gel pad using MeOH, concentrated, dissolved in K2CO₃ solution, washed with DCM, acidified with HCI, extracted with DCM, dried over MgS0₄ and concentrated to give the desired compound.

i) Optimization of the Reaction Conditions for the Oxidation of Toluene (Reaction A) and Ethylbenzene (Reaction B)^a.

The results are summarised below:

Reaction A Reaction B o

THBP, neat THBP, neat

80 °C, 16 h 80 °C, 16 h

a Reaction conditions: 70% aq. TBHP, neat, 80 °C, 16 h; ^b Catalyst loading: 5 mg/mmol of substrate, except entry 6; ^c Catalyst loading: 10 mg/mmol of substrate n.d. = not determined ii) Oxidation of various alkylarenes ³

The results are summarised below:

a Reaction conditions: TAL-1-900 (5 mg/mmol of substrate), 70% aq. TBHP, neat, 80 °C, 24 h.

Experimental procedures

Benzoic acid

From toluene. A mixture of toluene (100 mg, 1 .08 mmol, 1 .0 equiv), TBHP (70% aq solution, 892 mI_, 6.51 mmol, 6.0 equiv) and TAL-001 C@900L (5.4 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using MeOH, concentrated under reduced pressure, the residue was redissolved in K₂CO₃ solution (10 ml_), washed with DCM (2x 10 ml_), the combined aqueous phase was acidified with HCI, extracted with DCM (3x 10 ml_), dried over MgS0₄, and concentrated under reduced pressure to give the desired product as a colorless solid (48.4, 0.396 mmol, 37%). From benzylalcohol. A mixture of benzyl alcohol (100 mg, 0.925 mmol, 1.0 equiv), TBHP (70% aq solution, 380 mI_, 2.77 mmol, 3.0 equiv) and TAL-001 C@900L (4.6 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using MeOH, concentrated under reduced pressure, the residue was redissolved in K₂CO₃ solution (10 ml_), washed with DCM (2x10 ml_), the combined aqueous phase was acidified with HCI, extracted with DCM (3x10 ml_), dried over MgS0₄ and concentrated under reduced pressure to give the desired product as a colorless solid (94.5, 0.774 mmol, 84%).

From 2-phenylacetic acid with 3 equiv TBHP. A mixture of 2-phenylacetic acid (100 mg, 0.734 mmol, 1.0 equiv), TBHP (70% aq solution, 301 mI_, 2.20 mmol, 3.0 equiv) and TAL-001 C@900L (3.7 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using DCM, concentrated under reduced pressure, purified by flash chromatography (EtOAc/PE 1 :20) to give the desired product as a colorless solid (43.6 mg, 0.357 mmol, 49%).

From 2-phenylacetic acid with 6 equiv TBHP. A mixture of 2-phenylacetic acid (100 mg, 0.734 mmol, 1.0 equiv), TBHP (70% aq solution, 602 mI_, 4.40 mmol, 6.0 equiv) and TAL-001 C@900L (3.7 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using DCM, concentrated under reduced pressure, purified by flash chromatography (EtOAc/PE 1 :20) to give the desired product as a colorless solid (62.8 mg, 0.514 mmol, 70%).

¹³C NMR (100 MHz, CDCI3) d 172.5, 134.0, 130.4, 129.4, 128.6.

Isophthalic acid

A mixture of m-xylene (100 mg, 0.942 mmol, 1.0 equiv), TBHP (70% aq solution, 1 .55 ml_, 1 1.30 mmol, 12.0 equiv) and TAL-001 C@900L (4.7 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using MeOH, concentrated under reduced pressure and purified by flash chromatography (EtOAc/PE 1 :20 1 :10) to give the desired product as a colorless solid (50.0 mg, 0.301 mmol, 32%).

¹H NMR (400 MHz, DMSO-de) d 13.2 (s, 2H), 8.48 (s, 1 H), 8.17 (d, 1 H, J = 1 .6), 8.15 (d, 1 H, J = 1 .6), 7.64 (t, 1 H, J = 7.7)

¹³C NMR (100 MHz, DMSO-de) d 166.6, 133.4, 131.2, 130.0, 129.2.

4-Methylbenzoic acid

A mixture of p-xylene (100 mg, 0.942 mmol, 1 .0 equiv), TBHP (70% aq solution, 1 .55 mL, 1 1.30 mmol, 12.0 equiv) and TAL-001 C@900L (4.7 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using MeOH, concentrated under reduced pressure and purified by flash chromatography (EtOAc/PE 1 :20) to give the desired product as a colorless solid (43.5 mg, 0.320 mmol, 34%).

¹H NMR (400 MHz, CDCI₃) d 8.01 (d, 2H, J = 8.1 ), 7.28 (d, 2H, J = 8.1 ), 2.43 (s, 3H).

¹³C NMR (100 MHz, CDCIs) d 171 .9, 144.8, 130.4, 129.4, 126.7, 21 .9. 5-Methylisophthalic acid

A mixture of mesitylene (100 mg, 0.832 mmol, 1 .0 equiv), TBHP (70% aq solution, 2.05 ml_, 14.98 mmol, 18.0 equiv) and TAL-001 C@900L (4.2 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using MeOH, concentrated under reduced pressure and purified by flash chromatography (EtOAc/PE 1 :20 1 :10) to give the desired product as a colorless solid (57.2 mg, 0.317 mmol, 38%).

¹H NMR (400 MHz, DMSO-de) d 13.18 (s, 2H), 8.28 (s, 1 H), 7.98 (s, 2H), 2.43 (s, 3H).

¹³C NMR (100 MHz, DMSO-de) d 166.7, 138.8, 133.9, 131.2, 127.3, 20.6.

HRMS for C₉H₉O₄ [M+H]⁺ found 181.0496; calcd. 181.0495.

Acetophenone

With 3 equiv TBHP. A mixture of ethylbenzene (100 mg, 0.942 mmol, 1 .0 equiv), TBHP (70% aq solution, 387 pl_, 2.83 mmol, 3.0 equiv) and TAL-001 C@900L (4.7 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using MeOH, concentrated under reduced pressure and purified by flash chromatography (EtOAc/PE 1 :100) to give the desired compound as a colorless oil (56.9 mg, 0.474 mmol, 50%).

¹³C NMR (100 MHz, CDCI3) d 198.2, 137.2, 133.2, 128.6, 128.4, 26.7.

Benzophenone

With 6 equiv TBHP. A mixture of diphenylmethane (150 mg, 0.892 mmol, 1 .0 equiv), TBHP (70% aq solution, 732 pL, 5.34 mmol, 6.0 equiv) and TAL-001 C@900L (4.5 mg) was left to stir at 80 °C. After 24 h, it was filtered through a Celite pad using DCM, concentrated under reduced pressure and purified by flash chromatography (EtOAc/PE 1 :100) to give the desire compound as a colorless solid (152.5 mg, 0.837 mmol, 94%).

¹³C NMR (100 MHz, CDCI3) d 196.9, 137.7, 132.5, 130.2, 128.4.

Example 12 - Recycling experiments of TAL-X catalysts

The results are summarised below:

Reaction A Reaction B

OH

THBP, neat THBP, neat

80 °C, 16 h 80 °C, 16 h

Reaction conditions: 70% aq. TBHP, catalyst loading: 5 mg/mmol of substrate, neat, 80 °C, 16 h. Yields were determined by NMR using 1 ,3,5-trimethoxybenzene as internal standard.

The reactions were set up as per example 11 (catalyst loading: 5 mg/mmol of substrate). After 16 h, the catalyst was recovered by centrifuging the reaction mixture, washed with DCM, dried and reused. The filtrate was concentrated and analysed by NMR, while the catalyst was recycled.

As demonstrated by the Examples of the present invention, a new a class of multifunctional catalytic material has been provided. These materials have attractive properties and may be used to catalyse a range of electrochemical (e.g. ORR) or synthetic reactions (reductions, coupling- type reactions, radical reactions, etc).

The term“about” when used in reference to a stated value is used to indicate that the given value is approximate and may vary in a non-significant manner, typically about means the stated value plus or minus 5% of said value.

For the avoidance of doubt, the embodiments of any one feature of the compounds of the invention may be combined with any embodiment of another feature of compounds of the invention to create a further embodiment. Throughout the specification and the claims which follow, unless the context requires otherwise, the word‘comprise’, and variations such as‘comprises’ and‘comprising’, will be understood to imply the inclusion of a stated integer, step, group of integers or group of steps but not to the exclusion of any other integer, step, group of integers or group of steps. The application of which this description and claims forms part may be used as a basis for priority in respect of any subsequent application. The claims of such subsequent application may be directed to any feature or combination of features described herein. They may take the form of product, composition, process, or use claims and may include, by way of example and without limitation, the claims which follow.

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Claims

1. A method for forming a catalytic precursor, said method comprising the step of reacting a metal precursor with a benzoimidazolediol-type linker.

2. A method for forming a catalytic material, said method comprising the carbonisation of a catalyst precursor obtainable by reacting a metal precursor with a benzoimidazolediol-type linker. 3. A method for forming a catalytic material, said method comprising the steps:

(b) carbonisation of the catalyst precursor.

4. The method according to any one of claims 1 to 3, wherein the benzoimidazolediol-type linker comprises, such as consists of, a compound of formula (I):

wherein

Wi and W₂ are each independently selected from OH, NH2, SH, COOH, B(OH)2,

Si(OH)₃, CN, CºCH, CONH2, OCH₃, Ci-₆alkyl and halo;

X is selected from NH, O and S;

or a salt thereof.

5. The method according to any one of claims 1 to 3, wherein the benzoimidazolediol-type linker comprises, such as consists of, a compound of formula (I):

wherein

X is selected from NH, O and S;

or a salt thereof.

6. The method according to any one of claims 1 to 3, wherein the benzoimidazolediol-type linker comprises, such as consists of, a compound of formula (I):

wherein

Wi and W2 are each independently selected from OH, NH2, SH, COOH, B(OH)2, Si(OH)₃, CN, CºCH and CONH₂;

X is selected from NH, O and S;

7. The method according to any one of claims 1 to 6, wherein Y forms a linking group:

linking group

8. The method according to claim 7, when the linking group is phenyl. 9. The method according to claim 7, when the linking group is a C branched or unbranched saturated carbon chain or a Ci-₆ branched or unbranched unsaturated carbon chain, such as Ci-₆alkenylene or Ci-₆alkynylene.

10. The method according to any one of claims 7 to 9, wherein each Wi, W₂, Zi or Z₂ are the same.

1 1. The method according to any one of claims 1 to 10, wherein the benzoimidazolediol-type linker comprises at least two substructures of the formula

wherein

12. The method according to any one of claims 1 to 3, wherein the benzoimidazolediol-type linker comprises 1 /-/-benzo[c/]imidazole-5,6-diol, such as consists of 1 /-/-benzo[c/]imidazole-5,6- diol.

13. The method according to any one of claims 1 to 3, wherein the benzoimidazolediol-type linker is selected from the group consisting of

14. The method according to claim 13, wherein the benzoimidazolediol-type linker comprises

15. The method according to claim 13, wherein the benzoimidazolediol-type linker comprises

such as consists of

16. The method according to claim 13, wherein the benzoimidazolediol-type linker comprises

such as consists of

17. The method according to claim 13, wherein the benzoimidazolediol-type linker comprises

such as consists of

according to claim 13, wherein the benzoimidazolediol-type linker

such as consists of ording to claim 13, wherein the benzoimidazolediol-type linker

such as consists of

20. The method according to claim 13, wherein the benzoimidazolediol-type linker comprises

21. The method according to claim 13, wherein the benzoimidazolediol-type linker comprises

22. The method according to any one of claims 1 to 21 , wherein the metal precursor is a single source of metal ions.

23. The method according to any one of claims 1 to 21 , wherein the metal precursor comprises a source or sources for a plurality of metal ions.

24. The method according to any one of claims 1 to 23, wherein the metal precursor is a source of metal ions selected from the group consisting of Li⁺, Na⁺, K⁺, Rb⁺, Be²⁺, Mg²⁺, Ca²⁺,

25. The method according to any one of claims 1 to 24, wherein the metal precursor is a metal salt.

26. The method according to claim 25, wherein the metal salt is a salt of iron.

27. The method according to claim 25, wherein the metal salt is a salt of cobalt.

28. The method according to claim 25, wherein the metal salt is a salt of nickel.

29. The method according to claim 25, wherein the metal salt is a salt of manganese.

30. The method according to claim 25, wherein the metal salt is a salt of copper.

31 . The method according to claim 25, wherein the metal salt is a salt of zinc.

32. The method of any one of claims 3 to 31 , comprising the steps:

(b) isolation of the catalyst precursor;

(c) carbonisation of the catalyst precursor.

33. The method of any one of claims 2 to 32, comprising the additional step of leaching, such as acid leaching.

34. A catalyst precursor obtainable by the method of any one of claims 1 or 4 to 33.

35. Catalytic material obtainable by the method of any one of claims 2 to 33. 36. Use of catalytic material according to claim 35 to catalyse a chemical reaction.

37. A method for the catalysis of a chemical reaction comprising the steps:

(a) forming catalytic material according to claim 35; and

(b) catalysing the chemical reaction using said catalytic material.

38. The use or method according to any one of claim 35 to 37, wherein the chemical reaction is ORR.

39. The use or method according to any one of claims 35 to 37, wherein the chemical reaction is HER.

40. The use or method according to any one of claims 35 to 37, wherein the chemical reaction is OER. 41. An electrode comprising catalytic material according to claim 35.