CN109593207B

CN109593207B - Two-dimensional MOFs material with proton conductivity and preparation method thereof

Info

Publication number: CN109593207B
Application number: CN201811431284.4A
Authority: CN
Inventors: 段显英; 魏梅林
Original assignee: Institute of Chemistry Henan Academy of Sciences Co Ltd
Current assignee: Institute of Chemistry Henan Academy of Sciences Co Ltd
Priority date: 2018-11-26
Filing date: 2018-11-26
Publication date: 2021-01-05
Anticipated expiration: 2038-11-26
Also published as: CN109593207A

Abstract

The invention relates to the field of proton conducting materials, and discloses an MOFs material with excellent proton conducting property and a preparation method thereof. The process is carried out with H₄L is a linking ligand, Cu²⁺，Cl^‑For the connection point, a two-dimensional layer of the target material is prepared by heating. The material of the invention has good proton conductivity, simple and easy operation of the preparation method, high yield, stable thermodynamic and chemical properties, and easy large-area popularization and application.

Description

Two-dimensional MOFs material with proton conductivity and preparation method thereof

Technical Field

The invention belongs to the technical field of proton conducting materials, and relates to a two-dimensional MOFs material with proton conducting property and a preparation method thereof.

Background

Currently, numerous advanced energy storage and conversion devices are involved in the search for solutions to energy challenges and environmental issues, among which proton transfer membrane Fuel Cells are considered a very promising option, mainly due to their superior properties such as high energy density, low pollutant emissions and mild operating conditions (reference: Barbir F. PEM Fuel Cells: Theory and Practice. (Elsevier Academic Press, New York, 2005)). Although intensive research has been conducted in the field of proton transfer membrane fuel cells, the design and synthesis of electrode materials with high proton conductivity and stability remain a challenge. In addition, the lack of crystallinity of commonly used Nafion membranes in polymers makes it difficult to understand well-defined proton transport pathways at the atomic level. Over the past few decades, metal organic compounds (MOFs) have gained rapid growth with a growing interest, mainly due to their designable and tunable structure and properties, and potential applications in adsorption, separation, sensing and energy related applications (references: Denny m.s.jr, Moreton j.c., Benz L. & Cohen s.m.nat. rev.mater.2016,1,16078; Schoedel a., Ji Z. & Yaghi o.m.nat. energy,2016,1,16034; kren l.e., Leong k., Farha o.k., Allendorf, Van Duyne r.p.and Hupp j.t.chem.rev.2012,112, 1105). Current research indicates that proton conducting metal-organic materials can potentially be applied in proton transfer membrane fuel cells (references: ramasswamy p., Wong N.E. & Shimizu g.k.h.chem.soc.rev.,2014,43,5913; Horike s., Umeyama D. & Kitagawa s.acc.chem.res.,2013,46,2376.). On the other hand, in order to design a better proton conducting material, the metal organic material exhibits its advantages in many aspects, such as its crystalline nature may allow intuitive visualization of proton transport channel models; the regular structure is easy to introduce acidic groups, thereby forming effective proton transport channels and increasing proton conductivity (references: Taylor J.M., Mah R.K., Moudrakovski I.L., Ratcliffe C.I., Vaidhyatahan R., Shimizu G.K.H.J.Am.Chem.Soc.2010,132, 14055; Bao S.S., Shimizu G.K.H., Zheng L.M., coord. chem.Rev.,2019,1, 577-594.). Therefore, researches are explored to introduce bipyridyl-containing diphosphoric acid groups into metal organic materials so as to obtain two-dimensional proton conducting MOFs materials with better performance, which is beneficial to the development of fuel cells, and no relevant report is found at present.

Disclosure of Invention

The invention aims to provide a two-dimensional proton conductive MOFs material with good thermal stability, chemical stability and proton conductivity; another object is to provide a process for the preparation thereof.

In order to achieve the purpose, the invention constructs the metal organic compound based on 2,2 '-bipyridine-4, 4' -diphosphonic acid and tests the proton conductivity of the metal organic compound. The two-dimensional proton conductive MOFs material takes 2,2 '-bipyridine-4, 4' -diphosphonic acid as a ligand (H)₄L)，Cu²⁺，Cl^-And a two-dimensional layer structure is constructed as the connection point. Cu²⁺，Cl^-One-dimensional chains are formed in the c-direction and then through H in the b-direction₃L^-The ligands link the copper atoms of the upper and lower chains to form a two-dimensional layer. Unit cell parameters: belongs to monoclinic system, C2/C space group,

β＝100.391°,F(000)＝1656.0,

and Z is 8. The molecular formula is C₁₀H₉ClCuN₂O₆P₂The molecular structure is schematically shown in figure 1.

The synthesis method comprises the following steps: 2,2 '-bipyridine-4, 4' -diphosphonic acid and CuCl₂Adding the mixture into a mixed solution of water and concentrated hydrochloric acid, heating the mixture at 200-250 ℃ for reaction, and naturally cooling the mixture after the reaction is finished to obtain green crystals, thus obtaining the target material.

CuCl₂The mol ratio of the 2,2 '-bipyridine-4, 4' -diphosphonic acid is selected from: 1.0-2.0: 1.0;

the concentrated hydrochloric acid: selecting 1 part of water by mass: 5-8.

The synthetic route is as follows:

CuCl₂+H₄L→Cu-Cl-H₃L

the invention has the advantages that: the diphosphoric acid group is introduced, the synthesized two-dimensional proton conductive MOFs material has good crystallization capacity, higher thermal stability and chemical stability, good proton conductivity at medium and low temperature, and insolubility in various solvents provides possibility for material application, and shows attractive application prospect in the aspect of proton conductivity. The invention adopts one-step synthesis, has simple preparation and easily controlled conditions, and is easy for industrialized popularization and production.

Drawings

FIG. 1 is a schematic diagram of the structure of a compound of the present invention;

FIG. 2 is an infrared spectrum of a compound of the present invention;

FIG. 3 is a thermogram of a compound of the present invention;

FIG. 4 is an XRD pattern of a compound of the present invention, in which A-single crystal simulation, B-before conductivity test, and C-after conductivity test);

FIG. 5 is a graph of proton conductivity as a function of humidity for compounds of the present invention at 25 ℃ and 100 ℃;

FIG. 6 is an Arrhenius diagram showing proton conductivity at a temperature of 25 to 100 ℃ and a relative humidity of 98% for the compound of the present invention.

Detailed Description

To better illustrate the invention, the following examples are given:

example 1

0.05mmol of 2,2 '-bipyridine-4, 4' -diphosphonic acid and CuCl₂0.05mmol was placed in a bottle, and then concentrated hydrochloric acid: water (mass ratio) 1: adding 1.5ml of mixed solution into a bottle, heating at 200 ℃ for 5 hours, and naturally cooling to obtain green crystals. The infrared spectrum is shown in figure 2.

Unit cell parameters: the compound crystallizes in the monoclinic system, C2/C space group,

β＝100.391°,F(000)＝1656.0,

Z＝8。

example 2

0.05mmol of 2,2 '-bipyridine-4, 4' -diphosphonic acid and CuCl₂0.1mmol was placed in a bottle, and then concentrated hydrochloric acid: water (mass ratio) 1: 5 total 1.5ml of the mixed solution is added into a bottle, heated for 3 hours at 240 ℃, and naturally cooled to obtain green crystals. The infrared spectrum is shown in figure 2.

The proton conductivity of the resulting compound was tested: at a Relative Humidity (RH) of 98%, the proton conductivity of the compound increased with increasing temperature in a linear relationship, and was 1.97X 10 at 25 ℃ and 100 ℃ respectively^-4And 4.32X 10^-3S·cm^-1. Under these conditions, the activation energy of the compound was 0.41 eV. The powder proton conductivity of the compound at 25 ℃ does not change much with increasing humidity (1.64X 10 from RH 35%)^-41.96X 10 to RH 98%^-4S·cm^-1). The powder proton conductivity of the compound at 100 ℃ increased with increasing humidity (1.97X 10 from RH 35%)^-34.32X 10 to RH 98%^-3S·cm^-1) See fig. 5. The compound has good proton conductivity, so that the compound can be used as a proton conductive material in the field of fuel cellsPotential candidate solid materials for the material.

The structure of the compound shows that the compound is an anhydrous system, and the thermogravimetry shows that the compound does not lose weight below 100 ℃. See fig. 3. Therefore, the proton conductivity of the compound is derived from a hydrogen bond layer formed between the compound layer and the interlayer by a hydroxyl group and an oxygen atom on phosphoric acid. XRD of the compound before and after testing is basically unchanged, which shows that the skeleton of the compound is unchanged, and shows that the compound has good stability to water and good thermal stability, and is shown in figure 4.

Claims

1. The two-dimensional MOFs material with proton conductivity is characterized in that 2,2 '-bipyridine-4, 4' -diphosphonic acid H is used₄L is a ligand, Cu²⁺、Cl^-Two-dimensional layer structure constructed as connection point, Cu²⁺、Cl^-In thatcOne-dimensional chains are formed in the direction, thenbIn the direction of H₃L^-The ligand is connected with copper atoms of the upper chain and the lower chain to form a two-dimensional layer; the molecular formula is C₁₀H₉ClCuN₂O₆P₂The unit cell parameters are as follows: belongs to a monoclinic system and is characterized in that,C2/cthe space group is formed by the space group,a=22.9382 Å, b=7.9268 Å, c=14.9860 Å , β= 100.391°, F(000)=1656.0, V= 2680.1(5) Å³, Z=8。

2. a method for preparing two-dimensional MOFs materials with proton conducting properties according to claim 1, characterized by the following steps:

2,2 '-bipyridine-4, 4' -diphosphonic acid and CuCl₂Adding into the mixture of water and concentrated hydrochloric acid at 200-250 deg.C^oC, heating for reaction, and naturally cooling after the reaction is finished to obtain green crystals, so as to obtain the target material.

3. The method of preparing two-dimensional MOFs materials having proton conducting properties according to claim 2, wherein CuCl₂The mol ratio of the 2,2 '-bipyridine-4, 4' -diphosphonic acid is selected from: 1.0-2.0: 1.0; concentrated hydrochloric acid: selecting 1 part of water by mass: 5-8.