EP3999673A1 - Procédé de synthèse électrocatalytique efficace de solutions de produits liquides purs comprenant h2o2, des composés oxygénés, de l'ammoniac, etc - Google Patents

Procédé de synthèse électrocatalytique efficace de solutions de produits liquides purs comprenant h2o2, des composés oxygénés, de l'ammoniac, etc

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Publication number
EP3999673A1
EP3999673A1 EP20761367.0A EP20761367A EP3999673A1 EP 3999673 A1 EP3999673 A1 EP 3999673A1 EP 20761367 A EP20761367 A EP 20761367A EP 3999673 A1 EP3999673 A1 EP 3999673A1
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EP
European Patent Office
Prior art keywords
solid electrolyte
cathode
cell
porous solid
anode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
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EP20761367.0A
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German (de)
English (en)
Inventor
Haotian WANG
Chuan XIA
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William Marsh Rice University
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William Marsh Rice University
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Publication of EP3999673A1 publication Critical patent/EP3999673A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/27—Ammonia
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/28—Per-compounds
    • C25B1/30—Peroxides
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/042—Electrodes formed of a single material
    • C25B11/043—Carbon, e.g. diamond or graphene
    • C25B11/044—Impregnation of carbon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B13/00—Diaphragms; Spacing elements
    • C25B13/04—Diaphragms; Spacing elements characterised by the material
    • C25B13/05—Diaphragms; Spacing elements characterised by the material based on inorganic materials
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/25—Reduction

Definitions

  • Hydrogen peroxide is a nexus chemical for a variety of industries, and it is currently produced through an indirect, energy-demanding, and waste-intensive anthraquinone process.
  • This traditional method usually generates H 2 O 2 mixtures with concentrations of 1-2 wt.%, followed with further purifications and distillations, where significant costs adds up, to reach concentrated pure H 2 O 2 solutions for commercial use.
  • this process requires centralized infrastructures and thus relies heavily on transportation and storage of bulk H 2 O 2 solutions, which are unstable and hazardous.
  • the direct electrosynthesis of H 2 O 2 can decouple the H 2 /O 2 redox into two half-cell reactions (alkaline conditions for example): 2e -0 2 reduction reaction (2e -ORR): O 2 + H 2 O + 2e- HO 2 - + OH-; (Eq. 1)
  • Embodiments herein relate to an alternative and highly efficient concept that employs a porous solid electrolyte electrolytic cell comprised of a cathodic catalyst, an anodic catalyst, ion exchange membranes, and solid electrolyte wherein a porous solid electrolyte design is used to realize the direct electrosynthesis of pure H 2 O 2 as well as many other liquid product solutions.
  • the cathodic catalyst could be 2e oxygen reduction reaction catalyst (such as oxidized carbon) to generate pure H 2 O 2 solutions, or CO 2 /CO reduction catalyst for pure oxygenates solutions, or N 2 /Nq 3 /Nq 2 reduction catalyst for pure N species solutions, and so on.
  • Solid electrolytes can also be replaced with the corresponding liquid products if high ionic conductivity can be maintained.
  • embodiments disclosed herein generally relate to a porous solid electrolyte electrosynthesis cell for direct synthesis of high purity liquid products wherein the electrosynthesis cell comprises a cathode compartment including a cathode electrode comprising a gas diffusion layer loaded with a selective reduction reaction electrocatalyst for specific reduction reactions wherein the reduction reactions comprise oxygen reduction reactions, CO 2 reduction reactions, CO reduction reactions, N 2 reduction reactions, nitrate reduction reactions and nitrite reduction reactions.
  • the electrosynthesis cell further includes an anode compartment including an anode electrode comprising a gas diffusion layer loaded with a catalyst for oxidation reactions; a solid electrolyte compartment comprising a porous solid electrolyte; a cation exchange membrane; and an anion exchange membrane; wherein the solid electrolyte compartment is separated from the cathode and the anode by the anion exchange membrane and/or the cation exchange membrane.
  • embodiments disclosed herein generally relate to a process for producing high purity and concentrated liquid products through electrocatalytic reaction in an electrosynthesis cell comprising a cathode compartment including a cathode electrode comprising a gas diffusion layer loaded with a selective electrocatalyst for reduction reactions; an anode compartment including an anode electrode comprising a gas diffusion layer loaded with a catalyst for oxidation reactions; a solid electrolyte compartment comprising a porous solid electrolyte, an inlet, and an outlet; a cation exchange membrane; and an anion exchange membrane.
  • the process further includes supplying hydrogen gas or water solutions to the anode to be electrochemically oxidized on the oxidation reaction catalysts; and supplying an oxygen, CO 2 , CO, or N 2 containing gas to the cathode to be selectively reduced by the selective reduction reaction catalyst; wherein the solid electrolyte compartment is separated from the cathode and the anode by the anion exchange membrane and the cation exchange membrane.
  • the process further includes supplying deionized water or N 2 gas to an inlet of the solid electrolyte compartment to flow through the porous solid electrolyte to bring out the generated liquid product.
  • porous solid electrolyte electrosynthesis cell for direct synthesis of high purity liquid products
  • the porous solid electrolyte electrosynthesis cell includes a cathode compartment including a cathode electrode including a gas diffusion layer loaded with a selective reduction reaction electrocatalyst for specific reduction reactions.
  • the specific reduction reactions may include oxygen reduction reactions, CO 2 reduction reactions, CO reduction reactions, N 2 reduction reactions, nitrate reduction reactions and nitrite reduction reactions.
  • the electrosynthesis cell may further include an anode compartment including an anode electrode comprising a gas diffusion layer loaded with a catalyst for oxidation reactions.
  • the electrosynthesis cell may include a solid electrolyte compartment comprising a porous solid electrolyte, a first cation exchange membrane, and a second cation exchange membrane, where the solid electrolyte compartment may be separated from the each of the cathode and the anode by the first and second cation exchange membranes.
  • FIGS. 1A-1D show a (Fig. 1A) schematic of direct synthesis of H2O2 using diluted
  • Fig. IB shows a schematic of direct electrosynthesis of H2O2 using pure 3 ⁇ 4 and O2 streams separated into anode and cathode, respectively.
  • Fig. ID shows the corresponding FEs of H2O2 under different potentials.
  • FIG. 2 is a schematic design for an electrosynthesis cell for pure H2O2.
  • FIG. 3 is a schematic design for an electrosynthesis cell for CO2 reduction for the production of a variety of liquid products.
  • FIGS. 4A-4D show an (Fig. 4A) SEM image and (Fig. 4B) and BET surface area analysis of carbon black catalyst with different surface oxygen content.
  • Fig. 4C shows a representative SEM image of a spray coated CB-10% electrode with a roughly 70 pm thick catalyst layer.
  • Fig. 4D shows an enlarged SEM image of the CB-10% catalyst electrode demonstrating the high porosity of the catalyst layer on the GDF to provide for improved O2 diffusion and catalytic current density.
  • FIGs. 5A-5B show high-resolution (Fig. 5A) C Is and (Fig. 5B) O Is XPS spectra.
  • FIGs. 6A-6C shows (Fig. 6A) XPS survey scans of carbon black catalysts with different surface oxygen contents, (Fig. 6B) faradaic efficiencies, and (Fig. 6C) TV curves of carbon black catalysts with different surface oxygen contents for 2e -ORR using O 2 //SE//H 2Q cell configuration with solid proton conductor.
  • FIGs. 7A-H show a comparison of the four types of TM-CNT samples, including Fe,
  • FIGs. 8A-8G show (Fig. 8A) SEM, (Fig. 8B) TEM and (Fig. 8C) high-resolution TEM views of the BOON nanosheet.
  • Fig. 8D shows STEM-EDS elemental mapping of BOON.
  • Fig. 8E shows TEM and (Fig. 8F) high-resolution TEM images of in-situ reduced metallic 2D-BL
  • Fig. 8G shows in-situ Bi L3-edge XAS spectra of BOON at different potentials.
  • FIGs. 9A-9C show SEM images of solid polymer proton conductors.
  • Fig. 9A shows a zoomed out SEM view of sulfonated styrene-divinylbenzene copolymer proton conductor with successive zoom in views Fig. 9B and Fig. 9C demonstrating a uniform spherical morphology.
  • FIG. 10 shows 2e -ORR performance of CB-10% in solid electrolyte for a three- electrode cell.
  • FIGs. 11A-11D show (Fig. 11A) The I-V curve of CB-10%//SE//Pt-C cell with H + conducting porous solid-electrolyte.
  • Fig. 11B shows the corresponding FEs and production rates of H2O2 under different cell voltages.
  • Fig. 11C shows the dependences of H2O2 concentration on the DI water flow-rate under an overall current density of 200 mA/cm 2 .
  • Fig 11D shows the removal of TOC in Houston rainwater using the generated pure H2O2 solution under a current density of 200 mA/cm 2 .
  • FIGs. 12A-12B show stability tests of continuous generation of pure H2O2 solutions with concentrations over 1,000 and 10,000 ppm, respectively. No degradations were overserved in cell voltages and H2O2 concentrations over the 100-hour continuous operation.
  • the cell currents and DI flow-rates are (Fig. 12A) 60 mA under and 27 mL h-1 and (Fig. 12B) 120 mA and 5.4 mL h-1, respectively.
  • FIGs. 13A- 13B show H2O2 productivity of the presently described O2//SE//H2 system for (Fig. 13A) direct electrosynthesis and (Fig. 13B) direct synthesis compared with systems of the previous literature.
  • FIGs. 14A-14B show online 3 ⁇ 4 detection during H2O2 production and the XPS analysis of post-stability catalyst.
  • Fig. 14A shows gas chromatography analysis of cathode gas flow of CB-10%//SE//Pt-C cell during H2O2 production using O2 and 3 ⁇ 4.
  • Fig. 14B shows XPS survey scans of CB-10% catalyst after stability test under a relatively high current density.
  • FIGs. 15A-15D show pure H2O2 generation using O2 and 3 ⁇ 4 with polymer anion conductor and inorganic proton conductor.
  • the corresponding FEs and concentration of H2O2 products under different cell voltages are shown for (Fig. 15 A) an inorganic Cs A H - A PWi2O40 proton solid conductor and (Fig. 15D) anion conducting solid-electrolyte.
  • the DI flow-rate is 27 mF/h.
  • FIGs. 16A-16B show H2O2 faradaic efficiencies (FE)s as a function of DI water flow rate for (Fig. 16 A) O2//SE//H2 and (Fig. 16B) scaled-up unit cell, showing that the H2O2 selectivity was inhibited with increased H2O2 concentration.
  • FE H2O2 faradaic efficiencies
  • FIG. 17 shows a long-term operation test of the direct electro-synthesis of pure H2O2 solution using O2//SE//H2O cell, showing high selectivity and stability at 60 mA using this proposed system.
  • the FE of H2O2 is maintained constant ( ⁇ 95%) over the 100- hour continuous operation.
  • the DI flow-rate is 27 mF/h.
  • FIGs. 18A-18B show (Fig. 18A) the I-V curve of an O 2 //SE//H 2 O cell where H 2 O is oxidized on the anode side into protons and O 2 .
  • the 0.5 M H 2 SO 4 in water solution was used for improving the ionic conductivity on the anode side, and was not consumed during electrosynthesis.
  • Fig. 18B shows the corresponding FEs of H 2 //SE//H 2 O cell.
  • FIGs. 19A-19D show (Fig. 19A) the I-V curve and FEs of Air//SE//H 2 0 cell for generating pure H2O2 solutions. It demonstrated the generation of pure H2O2 solutions at a high production rate of 2.3 mmol cm-2 h-1 (2490 mol kgcat-1 h-1) using only air and water as cathode and anode feedstock, respectively, when pure 3 ⁇ 4 and O2 are not available.
  • Fig. 19B shows the I-V curve of the scaled-up unit cell module (80 cm 2 electrode, no // ⁇ -compensation), and (Fig. 19C) the corresponding H2O2 FEs. It confirms that the present approach can be scaled up with negligible sacrifice in performance.
  • Fig. 19D shows the dependence of H2O2 concentration (up to ⁇ 20 wt.%) on the DI water flow-rate while maintaining an overall current of 8 A.
  • FIGs. 20A-20E show (Fig. 20A) the current densities over cell voltages on 2D-Bi catalyst using the electrosynthesis cell for CO2 reduction with H + and HCOO- conducting solid-electrolyte.
  • Fig. 20D shows the dependencies of HCOOH concentration on the DI flow-rate maintaining an overall current density of 100 mA/ cm 2 , indicating that concentrated pure HCOOH solution (up to 6.73 M) can be continuously produced.
  • Fig. 20E shows the production of electrolyte-free C2 + liquid fuel solutions using commercial CU2O catalyst, showing that small molecular oxygenates liquid fuels can also be efficiently collected.
  • FIG. 21 shows the long-term operation test of CO2 reduction to pure HCOOH solution demonstrating the high selectivity and the stability of the 2D-Bi catalyst at 30 mA/cm 2 using this proposed CO2 reduction system.
  • the FE of HCOOH maintains more than 80% over the 100-hour continuous operation.
  • FIGs. 22A-B displays the current-voltage profile (Fig. 22B) of the direct electrocatalytic CO2 hydrogenation cell (Fig. 22A) for HCOOH vapor generation.
  • FIGs. 23A-E show the ORR performance of M-CNT catalysts cast RRDE in 0.1M
  • Fig. 23A shows linear sweep voltammetry measurements
  • Fig. 23B shows the calculated H2O2 selectivity and electron transfer number during potential sweep
  • Fig. 23C shows a stability measurement of Fe-CNT
  • Figs 23D-E show a comparison of LSV and corresponding H2O2 selectivity.
  • FIGs. 24A-B show the effects of Fe atom loading at respective amounts of 0, 0.05
  • FIGs. 25A-B show the bulk electrolysis for H202 generation in a homemade H-cell electrolyzer.
  • Fig. 25A shows an SEM image of GDL supported catalyst at a loading of 0.5 mg cm-2
  • Fig. 25B shows a polarization curve of Fe-CNT/GDL catalyst in 1 M KOH electrolyte
  • FIGs. 26A-B show the (Fig. 26A) XANES comparison of before, during, and after 2- h’s continuous ORR electrolysis at 0.55 V vs. RHE and (Fig. 26B) EXAFS of post catalysis Fe-CNT with Fe metal and Fe 3 0 4 as references.
  • FIGs. 27A-D show the disinfection performance of Fe-CNT in neutral pH.
  • Fig. 27 A- B is an LSV of Fe-CNT catalyst on RRDE with corresponding selectivity under different potentials;
  • Fig 27C shows LSV of Fe-CNT catalyst on GDL electrode in an H-cell electrolyzer;
  • Fig 27D shows bulk electrolysis at a constant current density in PBS containing E. coli bacteria.
  • FIG. 28 shows the The disinfection efficiency as a function of treatment time.
  • FIGs. 29A-C show the production of pure HCOOH solution and vapor using optimized CO2 reduction system with solid electrolyte.
  • Fig. 29A shows a Schematic illustration of the proposed four-chamber CO2 reduction cell with solid electrolyte.
  • Fig. 29B shows the current densities over cell voltages and the corresponding HCOOH FEs.
  • Fig. 29C shows the concentration of pure KOH which is simultaneously produced using the four-chamber solid cell during CO2 reduction.
  • FIGs. 30A-C show ORR performance of the catalysts cast RRDE in: Figs. 30A and
  • FIG. 30C shows linear sweep voltammetry (LSV) measurements of H2-annealed carbon black (denoted as ‘Pure C’) and boron, nitrogen, phosphorous, sulfur-doped carbon (denoted as‘B-C’, ‘N-C ⁇ ‘P-C ⁇ ‘S-C ⁇ respectively).
  • Figs. 30C and 30D show calculated H2O2 molar selectivity (left y-axis) and faradaic efficiency (right y-axis) during the potential sweep for different catalysts in 0.1M KOH and 0.1M Na 2 S0 4 , respectively.
  • FIGs. 31A-D show the three-electrode flow cell performance of catalysts.
  • Figs. 31A and 3 IB show I-V curves for Pure C, B-C and O-C inlM KOH and 1M Na 2 S0 4, respectively.
  • FIGs. 32A-B show solid-electrolyte cell performance for pure H2O2 generation. Fig.
  • FIG. 32A shows I-V curve and corresponding H2O2 faradaic efficiency
  • Fig. 32B shows H2O2 partial currents and H2O2 production rates under different applied potentials
  • Fig. 32C shows stability test of B-C fixed at 50mA cm 2 of generation of -1,100 ppm pure H2O2 solution.
  • the DI water feeding rate is fixed at 54 mL h 1 .
  • FIG. 33 shows a schematic of a H2O2 production reactor with two cation exchange membranes on each of the cathode and anode side.
  • FIG. 34 shows the stability of Ni-N-C single atom catalyst in the all CEM solid reactor.
  • FIG. 35 shows the electrochemical 2e -ORR performance of B-doped carbon.
  • any component described with regard to a figure in various embodiments of the present disclosure, may be equivalent to one or more like-named components described with regard to any other figure.
  • ordinal numbers e.g ., first, second, third, etc.
  • an element i.e ., any noun in the application.
  • the use of ordinal numbers is not to imply or create any particular ordering of the elements nor to limit any element to being only a single element unless expressly disclosed, such as by the use of the terms“before,”“after,”“single,” and other such terminology. Rather, the use of ordinal numbers is to distinguish between the elements.
  • a first element is distinct from a second element, and the first element may encompass more than one element and succeed (or precede) the second element in an ordering of elements, if an ordering exists.
  • One or more embodiments of the present disclosure relate to methods and systems for the production of high purity concentrated liquid products through electrocatalytic reactions.
  • One or more embodiments of the present disclosure relate to the production of H 2 O 2.
  • the described electrosynthesis cell may be used in the production of highly pure formic acid and / or other liquid fuels through the elctrocatalytic reduction of C0 2 or CO with solid electrolytes.
  • other pure liquid products including methanol, ethanol, n- propanol, formic acid, acetic acid and other organic oxygenates from CO 2 reduction reactions (CO 2 RR) or CO reductions (CORR) can be realized utilizing the general process and electrosynthesis cell described in one or more embodiments of the present disclosure.
  • the produced liquid product may be produced through superior selectivity of employed catalyst to achieve the continuous production of high purity concentrated liquid products that do not require any additional separation steps to achieve pure product solutions.
  • One or more embodiments of the present disclosure may be directed towards processes for the highly efficient and large-scale synthesis of commercial-level concentrated H2O2 via a cost-effective electrocatalytic oxygen reduction route (ORR).
  • ORR electrocatalytic oxygen reduction route
  • One or more embodiments of the present disclosure may relate to systems that may include a three-compartment electrosynthesis cell for direct pure liquid product production without any additional energy-intensive purification steps.
  • One or more embodiments of the present disclosure may relate to systems and methods that may include a four-compartment electrosynthesis cell for the simultaneously production of up to three kinds of high-purity products, in which an alkaline/neutral solution can be used for OER anode catalyst for direct pure liquid product production without any additional energy-intensive purification steps.
  • systems and methods that may include a four-compartment electrosynthesis cell where the solid electrolyte may be split and separated by bipolar membrane.
  • noble metal catalysts of the anode may be excluded and/or replaced.
  • a nickel iron layered double hydroxide (NiFe-LDH) and KOH may be chosen as the OER catalyst and electrolyte to decrease the catalyst cost and anode over potential.
  • One or more embodiments of the present disclosure are provided to introduce a highly efficient process and electrolytic cell capable of achieving high current efficiency for the direct and continuous production of pure ( ⁇ 20wt%) hydrogen peroxide (H2O2) via electrocatalytic synthesis.
  • One or more embodiments of the present disclosure is directed to processes
  • electrosynthesis cell with highly active electrocatalyst to achieve highly pure and concentrated liquid products from electrocatalytic reactions, e.g. 20wt % pure H2O2 solution from ORR.
  • electrocatalytic reactions e.g. 20wt % pure H2O2 solution from ORR.
  • present disclosure subverts the need for an energy-intensive purification step, as the immediate product of the governing system is an already pure form of H2O2 solutions.
  • One or more embodiments of the present disclosure may include a three-compartment electrolytic cell including a (cathode), a catalyst, such as hFh/C for water oxidation or Pt/C for 3 ⁇ 4 oxidation (anode) and a solid electrolyte. More particularly, one or more embodiments herein relate to a process for the on-site production of highly pure hydrogen peroxide via electrocatalytic oxygen reduction reaction (ORR, O 2 + H 2 O + 2e HO 2 + OH ), which can be used for bleaching, medical uses, food cleaning and processing, and other applications, together with oxygen at the counter side by water oxidation (OER, 23 ⁇ 40 O 2 + 4H + + 4e ).
  • ORR electrocatalytic oxygen reduction reaction
  • OER electrocatalytic oxygen reduction reaction
  • the cathode and anode of the proposed cell may be catalyst coated gas diffusion layer (GDL) electrodes, which are separated by an anion and cation exchange membrane, respectively.
  • GDL gas diffusion layer
  • Electrocatalytic reduction of oxygen (ORR) at the cathode and water oxidation at the anode may be used to generate anions (such as HO 2 ) and cations (such as H + ) respectively, which when driven through the appropriate ion exchange membranes ionically recombine to form pure H 2 O 2 .
  • O 2 generated at the anode can be driven back to the cathode to further undergo reduction, thereby contributing to the overall efficiency of the presented H 2 O 2 synthetic system.
  • the processes for the electrosynthesis of highly pure and concentrated liquid products may utilize a three- compartment electrolsynthesis cell, i.e. a cell partitioned into an anode compartment, an intermediate solid electrolyte compartment, and a cathode compartment wherein the cells are partitioned by cation or anion ion-exchange membranes, to produce liquid products.
  • a three- compartment electrolsynthesis cell i.e. a cell partitioned into an anode compartment, an intermediate solid electrolyte compartment, and a cathode compartment wherein the cells are partitioned by cation or anion ion-exchange membranes, to produce liquid products.
  • the cathode and anode of the proposed cell may be catalyst coated GDL electrodes, which were separated by anion and cation exchange membranes, respectively.
  • porous solid ion conductors e.g. H + or HO 2 conductors
  • porous solid ion conductors may be filled in between the membranes or electrodes with close contact.
  • a PSMIM anion exchange membrane and a Nafion membrane may be used for anion and cation exchange, respectively.
  • Other anion and cation exchange membranes may be used, alternatively.
  • Two Nafion membranes may be used, alternatively.
  • the solid electrolyte as denoted in Fig.
  • IB may be made of ion-conducting polymers with different functional groups, such as porous styrene-divinylbenzene copolymer consisting of sulfonic acid functional groups for cation conduction, or quaternary amino functional groups for anion conduction.
  • the cathode electrode where O 2 is reduced can be supplied with humidified O 2 gas to facilitate O 2 mass transport, whereas the anode side can be circulated with an acid solution, such as 0.5 M H 2 SO 4, for water oxidation using commercially-available Ir0 2 /C catalyst.
  • the anode side can also oxidize 3 ⁇ 4 to generate H + , in one or more embodiments.
  • oxygen gas or an oxygen-containing gas such as air
  • hydrogen gas or water may be supplied to the cathode
  • hydrogen gas or water may be supplied to the anode.
  • gases may be externally fed.
  • the two gases produced by water electrolysis can be rerouted and directly fed to the electrolytic cell.
  • the cathode of the electrosynthesis cell may be catalyst coated gas diffusion layer (GDL) electrodes.
  • the cathode electrode may be included in the cathode compartment of the three-compartment electrosynthesis cell.
  • the cathode electrode may include a gas diffusion layer that may be loaded with a selective reduction reaction electrocatalyst for specific reduction reactions.
  • the specific reduction reactions may include one or more of, oxygen reduction reactions, CO 2 reduction reactions, CO reduction reactions, N 2 reduction reactions, nitrate reduction reactions and nitrite reduction reactions, or combinations thereof.
  • the cathode may be selected from an oxygen-reducing electrode that includes a gas diffusion layer coated in a product selective electrocatalyst such as oxidized carbon material including carbon black, graphene, carbon nanotubes, or a mixture thereof.
  • a product selective electrocatalyst such as oxidized carbon material including carbon black, graphene, carbon nanotubes, or a mixture thereof.
  • the product selective electrocatalyst such as carbon material including carbon black, graphene, carbon nanotubes, or a mixture thereof, where the carbon material may include a non- metal dopant anchored on the carbon substrate.
  • Non-metal dopants may include boron, nitrogen, phosphorous, sulfur, or a combination thereof.
  • examples of other electrocatalyst for coating a gas diffusion layer may included N-, P-, S-, B-, Si-, or metal-doped carbon materials, or Bi, Cu, Ni, Fe, Co, Pd, In, Pb, Tn, transition metals, single atom catalysts of transition metals anchored into carbon nanotubes (CNT), oxides, chalcogenides thereof, or a mixture thereof.
  • the cathode maybe comprised of a gas diffusion layer coated in a carbon black electrocatalyst that may be optionally oxidized.
  • the carbon black may be pretreated before coating the GDL during the preparation of the cathode electrode.
  • Carbon black may be acid treated to realize and optimize surface ether and carboxyl functionalization to improve selectivity towards the desired 2e -ORR pathway.
  • the cathode of the electrosynthesis cell may be catalyst coated gas diffusion layer (GDL) electrodes where the catalyst may be loaded on the GDL electrode in an amount ranging from 0.01 mg/cm 2 to 20 mg/cm 2 .
  • the cathode of the electrosynthesis cell may be catalyst coated gas diffusion layer (GDL) electrodes where the catalyst may be loaded on the GDL electrode in an amount ranging from 0.01, 0.1, 0.3, 0.5, 1, 3, 5, 7, and 9 mg/cm 2 to 0.2, 0.3, 0.4, 0.6, 1, 2, 5, 8, 10, 15, and 20 mg/cm 2 , where any lower limit may be combined with any mathematically feasible upper limit.
  • the specific electrocatalyst for H2O2 production may be a low-cost oxidized carbon black, which may be directly synthesized and treated by oxidation of commercial carbon black (such as Vulcan XR-72R) in acid solution.
  • carbon black may be oxidized by mixing and refluxing the carbon black in a concentrated acid solution for an amount of time ranging from 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24, 30, 36 and 40 hours (hrs) to 2, 3, 5, 8, 10, 12, 16, 20, 24, 30, 36, 40, and 48 hrs, where any lower limit may be combined with any mathematically feasible upper limit.
  • commercial carbon black may be oxidized in a solution of 12 M HNO3 for 3 hrs.
  • the treated and oxidized carbon black cathode catalyst may have a surface oxygen content ranging from 0.1, 1, 2, 3, 5, 7, 10, 15, 20, and 25% to 2, 3, 7, 8, 11, 13, 15, 18, 20, 25, and 30%, wherein any lower limit may be combined with any mathematically feasible upper limit.
  • the cathode may be selected from an oxygen-reducing electrode comprised of a gas diffusion layer coated in a product selective electrocatalyst such as transition metal (TM) single atoms including Fe, Co, Ni, Cu, Zn, Pt, Pd, Ir, Mn, Cr that may be optionally anchored into carbon nanotube (TM- CNT) vacancies.
  • TM transition metal
  • the cathode may be selected from an oxygen-reducing electrode comprised of a gas diffusion layer coated in a product selective electrocatalyst such as Fe-CNT, Pd-CNT, Co-CNT, and Mn-CNT, or combinations thereof.
  • a product selective electrocatalyst such as Fe-CNT, Pd-CNT, Co-CNT, and Mn-CNT, or combinations thereof.
  • the cathode may be selected from an oxygen-reducing electrode comprised of a gas diffusion layer coated in a product selective electrocatalyst such as transition metal (TM) single atoms and non-metal dopants that include B, N, O, F, S, P, Si, Cl, etc.
  • TM transition metal
  • Fe-C-0 single atom catalyst is shown herein to demonstrate an excellent H2O2 Faradaic efficiency in both alkaline and neutral pH ( Figure 4), which can be directly used in our solid electrolyte cell for pure H2O2 solutions.
  • the single atom TM may anchored into the CNT in an amount ranging from 0.01 to 5 at%. In one or more embodiments the TM may anchored into the CNT in an amount ranging from 0.01, 0.05, 0.1, 0.15, 0.2, 0.3, 0.5, 0.8, 1, 1.5, 2, 3, and 4 at% to 0.1, 0.15. 0.18, 0.2 0.25, 0.3, 0.5, 0.8, 1, 1.5, 2, 3, 4, and 5 at%, wherein any lower limit may be combined with any mathematically feasible upper limit.
  • TM single atoms catalysts of one or more embodiments of the present disclosure may be prepared from metal cations (-0.1 at%) that may be first dispersed onto commercial surface-functionalized CNTs as the carbon matrix, and suspended in water. They may then be further treated through steps of freeze drying and thermos annealing under inert gas at about 500 to 1000 °C.
  • the product selective catalyst may be an ultrathin two- dimensional Bismuth (2D-Bi) catalyst for CC -to-HCOOH conversion.
  • the product selective catalyst may be an ultrathin two- dimensional Bi (2D-Bi) catalyst where at least 50% of the Bi sites of the 2D-Bi were electrochemically active using cyclic voltammetry. This high percentage may ensure high Bi atom efficiency during CO2RR catalysis.
  • the electrosynthesis cell including a cathode of a gas diffusion layer coated in a product selective electrocatalyst may generate a liquid product with a Faradaic selectivity ranging from 10% to 99.9%.
  • the gas diffusion layer coated in a product selective electrocatalyst may generate a liquid product with a Faradaic selectivity ranging from 10, 20, 30, 40, 50, 60, 70, 80, 90 95, and 97% to 50, 60, 70, 80, 85, 90, 93, 95, 97, and 99.9%, wherein any lower limit may be combined with any mathematically feasible upper limit.
  • the electrosynthesis cell including a cathode of a gas diffusion layer coated in a product selective electrocatalyst may deliver a final liquid product with a tunable FE that ranges from 10% to 99.9%.
  • the electrosynthesis cell including a cathode of a gas diffusion layer coated in a product selective electrocatalyst may deliver a liquid product with a FE that ranges from 30, 40, 50, 60, 70, 80, 90 95, and 97% to 50, 60, 70, 80, 85, 90, 93, 95, 97, and 99%, wherein any lower limit may be combined with any mathematically feasible upper limit.
  • the FE may be tunes by controlling the current density.
  • the cathode electrode may have an electrode area that ranges from 1 cm 2 to 10 m 2 per unit cell, which can be scaled up by stacking multiple cells.
  • the anode for use in the present disclosure may be selected from a gas diffusion electrode, hydrogen-oxidizing electrode, or a catalyst coated gas diffusion electrode, according to the electrolysis conditions.
  • examples of anode electrocatalyst for coating a gas diffusion layer include metal-doped carbon materials, or Ru, Ir, Pt, Ni, Ce, among other transition metals, single atom catalysts, an oxide or a chalcogenide thereof.
  • the oxygen-generating electrode may be a gas diffusion layer coated with a catalyst electrode material consisting mainly of a metal such as platinum, iridium, or ruthenium, an oxide of such a metal, or an oxide metal carbon compound as a catalyst and is used as such.
  • the oxygen-generating electrode may be a gas diffusion layer coated with a catalyst electrode material consisting of a nickel iron layered double hydroxide (NiFe-LDH).
  • the anode of the electrosynthesis cell may be catalyst coated gas diffusion layer (GDL) electrodes where the catalyst may be loaded on the GDL electrode in an amount ranging from 0.01 mg/cm 2 to 10 mg/cm 2 .
  • the cathode of the electrosynthesis cell may be catalyst coated gas diffusion layer (GDL) electrodes where the catalyst may be loaded on the GDL electrode in an amount ranging from 0.1, 0.2, 0.3, 0.35, 0.4, 0.5, 0.8, 1, 1.5, 3, 5, and 7 mg/cm 2 to 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1, 1.5, 3, 5, 8, and 10 mg/cm 2 , where any lower limit may be combined with any mathematically feasible upper limit.
  • GDL gas diffusion layer
  • the anode electrode may have an electrode area that ranges from 1 cm 2 to 10 m 2 per unit cell, which can be scaled up by stacking multiple cells.
  • the ion exchange membrane may be a cation and/or anion exchange membrane.
  • the cation and/or anion exchange membranes of the present disclosure may not be particularly limited.
  • the cation exchange membrane may be a perfluoro sulfonic acid (PFSA) membrane and the anion exchange membrane may be a membrane comprising a co-polymer of polystyrene cross linked with divinylbenzene and polystyrene methyl imidazolium chloride (PSMIM).
  • PFSA perfluoro sulfonic acid
  • PSMIM polystyrene methyl imidazolium chloride
  • AEMs are also feasible, such as polybenzimidazole membrane (PBI), benzyltrimethylammonium grafted PTFE membrane, vinyl-benzyl chloride grafted fully fluorinated poly(tetrafluoroethylene-co-hexafluoropropylene) membrane and chloromethylated polysulfones membrane.
  • PBI polybenzimidazole membrane
  • benzyltrimethylammonium grafted PTFE membrane vinyl-benzyl chloride grafted fully fluorinated poly(tetrafluoroethylene-co-hexafluoropropylene) membrane
  • chloromethylated polysulfones membrane chloromethylated polysulfones membrane.
  • the cation and anion exchange membranes may be interchangeable or selectively used in multiple configurations at either the cathode side or the anode side of the electrosynthesis cell.
  • the solid electrolyte material disposed between the cathode and anode may include ion-exchange resins and matrixes comprising an ion conducting material.
  • the porous solid electrolyte may be selected from a group of ion conducting polymers including polymers or copolymers of styrene, acrylic acid, aromatic polymers, or a combination thereof.
  • the porous solid electrolyte may be selected from an inorganic ceramic solid electrolyte, a polymer/ceramic hybrid solid electrolyte, solidified gel electrolytes, or ion conducting polymers, or a combination thereof.
  • the porous solid electrolyte is a porous styrene divinylbenzene copolymer consisting of sulfonic acid functional groups for cation conduction, or quaternary amino functional groups for anion conduction.
  • the solid electrolyte resins may include hydrocarbon resins such as styrene polymers, acrylic acid polymers and aromatic polymers.
  • the sulfonated inorganic materials like sulfonated carbon, S1O2, T1O2, WO3, CeC , TiC, MoC et al., may also be used as solid electrolyte.
  • the solid proton conductor may be prepared by refluxing porous (pore size ranges from 2 nm to 100 nm) or solid polymer or inorganic matrix in fuming acid, such as H2SO4 for about 24-h at an elevated temperature of about 80 °C.
  • the solid electrolyte comprised ion-conducting polymers with different functional groups, such as porous styrene- divinylbenzene copolymer consisting of sulfonic acid functional groups for H + conduction, or quaternary amino functional groups for anion conduction.
  • the solid electrolyte is not limited and may be an anion polymer conductor for anion or an inorganic solid cation conductor for pure generation comprised of Cs x H3- x PWi204o.
  • the porous styrene-divinylbenzene copolymer may be one of styrene-divinylbenzene sulfonated copolymer such as SSE 50 or SSE 300.
  • One or more embodiments may comprise other forms of solid electrolytes, such as ceramics, polymer/ceramic hybrids, or solidified gel electrolytes (e.g. 10 wt% H 3 P0 4 /polyvinylpyrrolidone gel).
  • the gas diffusion layers of the present disclosure are not particularly limited.
  • the gas diffusion layer may be a thin carbon-based porous medium that must provide high electrical and thermal conductivity and chemical and corrosion resistance, in addition to controlling the proper flow of reactant gases (hydrogen and air) to ensure uniform distribution of reactive gases on the surface of the electrodes.
  • the gas diffusion layers may be coated in a catalyst to form either the cathode or anode of the electrosynthesis cell.
  • the hydrogen gas and oxygen gas may be supplied, or hydrogen and oxygen gases may be generated by water electrolysis and may be directly supplied to the electrolytic cell.
  • the cathode side may be supplied with a controlled and tunable amount of O2, CO2, CO, N2, air, or other reactants and the anode side may be supplied with enough of 3 ⁇ 4, H2O, alkaline solutions, acidic solutions, or other reactants.
  • the cathode side may be supplied with a controlled and tunable amount of gas at a flow rate ranging from 0.001 to 1000 SLM.
  • the gas flow rate may change depending upon the device capacity.
  • pure water may be fed to the solid electrolyte compartment at a suitable rate depending on the size of reactor and the need of product concentration.
  • the water flow rate in a unit cell may range from 1 uL/h to 10 m 3 /h.
  • the specific water flow rate may be tuned relative to the target product fluid and its concentration.
  • the process and electrosynthesis cell may be used to obtain pure liquid products such as H2O2, methanol, ethanol, n-propanol, formic acid, acetic acid, other organic alcohols and acids, or ammonia from CO2 reduction reactions (CO2RR), CO reduction reactions, N2 reduction reactions, nitrate or nitrite reductions, and so on.
  • pure liquid products such as H2O2, methanol, ethanol, n-propanol, formic acid, acetic acid, other organic alcohols and acids, or ammonia from CO2 reduction reactions (CO2RR), CO reduction reactions, N2 reduction reactions, nitrate or nitrite reductions, and so on.
  • the electrosynthesis cell may capable of generating a concentrated liquid product.
  • the electrosynthesis cell may generate a liquid product, such as H2O2 , with a concentration ranging from 0.01 to 20 wt.%.
  • the electrosynthesis cell may generate a liquid product, such as H2O2 , with a concentration ranging from 0.01, 0.1, 1, 3, 5, 8, 10, 14, 16, and 18 wt.% to 8, 10, 12, 14, 16, 18 and 20 wt.%, wherein any lower limit may be combined with any mathematically feasible upper limit.
  • the electrosynthesis cell may be tuned to selectively operate at a current density ranging from 1 mA/cm 2 to 100 A/cm 2 .
  • the electrolysis conditions of the electrosynthesis cell may include operating at a liquid temperature ranging from 1 to 95° C.
  • a pure product such as hydrogen peroxide (H2O2)
  • H2O2 hydrogen peroxide
  • 0 2 may be reduced by the H 2 0 2 -selective catalyst, and the generated negatively charged HO2 may then be driven by the electrical field to travel through the AEM towards the middle solid electrolyte channel.
  • protons generated by water oxidation or hydrogen oxidation on the anode side may move across the CEM to compensate the charge.
  • pure H2O2 product can be formed via the ionic recombination of crossed ions either at the left (H + -conducting polymer) or right (HO2 conducting polymer) interface between the middle channel and membrane. Then, the formed liquid products may be quickly released by the slow deionized water (DI) stream or humidified inert gas flow.
  • DI deionized water
  • the DI flow rate may be at least 1 ul/hr and may be dependent on the size and/or capacity of the device.
  • the cathode electrode, where O2 is reduced may be supplied with humidified O2 gas to facilitate O2 mass transport, whereas the anode side may be circulated with a solution such as 0.5 M H2SO4 for water oxidation using commercial-available IrCh/C catalyst, or 3 ⁇ 4 gas using commercial-available Pt/C catalyst.
  • 3 ⁇ 4 can be electrochemically oxidized on a HOR catalyst, which may be coated on a gas diffusion layer electrode, into H + ; on the cathode side, by designing a 2e -ORR selective catalyst, O2 can be selectively reduced through the 2e- pathway into HO2 (Eq. 1), instead of OH as in traditional H2/O2 fuel cells.
  • HOR and 2e -ORR catalysts are in close contact with cation and anion exchange membranes (CEM and AEM), respectively, to avoid flooding issues from the direct contact with liquid water.
  • the electrochemically generated anions (HO 2 ) and cations (H + ) then move across the corresponding membranes into a thin layer of porous solid electrolyte, which plays a key role in both ion conduction and pure product collection.
  • ions can be efficiently conducted through the solid electrolyte with small ohmic losses for high cell efficiencies, particularly under large current densities.
  • H 2 O 2 molecules can be formed via the ionic recombination of crossed HO 2 and H + ions in the solid electrolyte layer, which were dissolved in the DI water stream and quickly released as pure H 2 O 2 solutions with no other impurity ions involved.
  • the porous solid electrolyte may be either anion or cation solid conductor, which can be made of ion conducting polymers with different functional groups, inorganic compounds, or other types of solid electrolyte materials such as ceramics, polymer/ceramic hybrids or solidified gels.
  • Fig. 3 illustrates an electrosynthesis cell for the reduction of CO 2 wherein the anode is coated with a stable and active HOR or oxygen evolution reaction catalyst (OER, in acidic solutions), which helps release H + from water to compensate for negative charges of generated formic acid ions.
  • OER oxygen evolution reaction catalyst
  • the electrosynthesis cell and process in accordance with one or more embodiments of the present disclosure may be able to achieve high H 2 O 2 selectivity of 95%, productivity (at 180 mA/cm 2 partial current or 3660 mol/kg cat h), and a liquid product concentration of 20 wt.%.
  • productivity at 180 mA/cm 2 partial current or 3660 mol/kg cat h
  • a liquid product concentration of 20 wt.% a 100-hour continuous and stable generation of ⁇ 1.1 wt.% ( ⁇ 11,000 ppm) pure H2O2 solution is demonstrated herein. It is also shown that similar H2O2 activity and selectivity can be obtained while using air and water for 2e -ORR and oxygen evolution reaction (OER), respectively, making on-site applications more accessible compared to pure 3 ⁇ 4 and O2.
  • OER oxygen evolution reaction
  • TOC total organic carbon
  • Carbon black is demonstrated herein as the starting material due to the following detailed and demonstrated reasons.
  • the nanoparticulate morphology of carbon black allows for effective O2 diffusions from GDL to the surface layer of catalyst (Figs. 4C-4D). This ensures efficient operations particularly under large current densities.
  • ether C-O-C
  • carbon black nanoparticles may be treated in nitric acid to realize surface ether and carboxyl functionalization.
  • compositions of carbon black were prepared by adding 600 mg of commercial carbon black (XC-72, FuelCellStore) into 600 mL of 12.0 M nitric acid. Then, the above solution was refluxed at 85 °C for 1, 3 and 12 h, respectively, to obtain oxidized carbon black with surface oxygen content of 7.33%, 10.19% and 11.62%, respectively. After natural cooling, the slurry was taken out, centrifuged and washed with water and ethanol until the pH was neutral. Finally, the sample was dried at 70 °C in a vacuum oven. The as-received commercial carbon black shows a 2.33% surface oxygen content.
  • the CB-10% catalyst can be de-convoluted into five contributions that are sp2 carbon at 284.6 eV, sp3 carbon at 285.5 eV, C-0 at 286.8 eV, -COOH at 288.9 eV and the characteristic shakeup line of carbon in aromatic compounds at 291.2 eV (p-p* transition).
  • the last component with B.E. around 535.5 eV was characteristic of adsorbed water.
  • the cathode may be selected from an oxygen-reducing electrode comprised of a gas diffusion layer coated in a product selective electrocatalyst such as transition metal (TM) single atoms including Fe, Pd, Co, and Mn that may be optionally anchored into carbon nanotube (TM-CNT) vacancies.
  • TM transition metal
  • TM-CNT carbon nanotube
  • TM-CNT catalysts were prepared by an impregnation and reduction method.
  • a 7.5-mM iron nitrate stock solution was first prepared by dissolving Fe(N0 3 ) 3 -9H 2 0 (ACS Grade, Alfa Aesar) into Millipore water (18.2 MW-cm).
  • a carbon suspension was prepared by mixing 50 mg multi-walled carbon nanotubes (Carbon Nanotubes Plus GCM389, used as received) with 20 mL of Millipore water, and tip sonicated (Branson Digital Sonifier) for 30 min till a homogeneous dispersion.
  • Pd-, Co-, and Mn-CNTs were prepared in a similar way to Fe-CNT except for various metal salt precursors, i.e., Pd(N03)2-2H20, Co(N03)2-6H20, and Mh(Nq3)2 ⁇ 4H2q (Puriss or ACS Grade, Sigma- Aldrich), respectively.
  • N doped Fe-N-CNT was prepared by heating up the above-mentioned Fe(N03)3/CNT powder under a same temperature program with Fe-CNT but within a mixed gas flow of 50 seem NFF (anhydrous, Airgas) + 100 seem Ar.
  • FIGs 7A-H show a comparison of the four types of TM-CNT samples, including Fe,
  • TM atoms Pd, Co, and Mn, which are demonstrated to have similar structures by transmission electron microscopy (TEM) and aberration-corrected high-angle annular dark-field scanning TEM (HAADF-STEM). No nanoparticles or clusters were observed in the bright field TEM images by different scales as shown by FIGs. 7A-D. This suggests a good dispersion of TM atoms. Isolated TM atoms can be resolved by HAADF- STEM due to their high Z-contrast compared to those neighboring light elements such as C or O. While all four isolated metal atoms were observed as the white dots in FIG.
  • TEM transmission electron microscopy
  • HAADF-STEM aberration-corrected high-angle annular dark-field scanning TEM
  • Pd-CNT presents the most distinguishable single atoms due to its heaviest atomic mass compared to the other three metal elements.
  • the oxidation state of coordinated Fe is lower than simply adsorbed Fe on CNT, suggesting the different chemical environment between the adsorption case and coordination case
  • Fe-CNT is further demonstrated herein to provide excellent performance towards H2O2 generation in terms of activity and selectivity. Fe-CNT was analyzed as a representative of other M-CNTs
  • HCOOH-selective electrocatalysts such as Bi, Co, Pd, In, Pb, Sn, and carbonaceous material
  • FEs peak faradaic efficiencies
  • cetyltrimethylammonium bromide was used as surface capping agent to obtain ultrathin 2D-BL Br- ions have been demonstrated to suppress the stacking of monolayers for Bi-compound during bottom-up synthesis system, and the extra surface repulsion from the hydrophobic long chains of CTA+ ions could further terminate the stacking of layered basic bismuth nitrates.
  • XAS In-operando X-ray absorption spectroscopic
  • Fig. 8G further shows the in-situ Bi L3-edge normalized absorption spectra under different applied potentials, as well as commercial Bi metal as a reference.
  • a negative energy shift of Bi edge was observed from open circuit voltage (OCV) to -0.32 V vs. reversible hydrogen electrode (RHE), suggesting the reduction of Bi oxidation states.
  • OCV open circuit voltage
  • RHE reversible hydrogen electrode
  • styrene-divinylbenzene copolymer microspheres consisting of sulfonic acid functional groups for cation (H + ) conductions, serves as the SE layer with micron pores in between for water flow and product release.
  • H + sulfonic acid functional groups for cation
  • Other types of solid electrolytes including anion (HO2 ) polymer conductors and cation inorganic conductors were also demonstrated for pure H2O2 generation.
  • FIG. 10 plots the I- V curve of CB-10%//SE//Pt-C cell with O2 and 3 ⁇ 4 gas streams in the cathode and anode, respectively.
  • the cell voltages are defined as negative when the device can output electrical energy during the production of H2O2.
  • the positive cell voltages thereby suggest the external energy input to this reactor.
  • the DI water flow rate was fixed at 27 mL/h for this 4 cm 2 electrode cell to prevent significant product accumulation particularly under large currents.
  • H2O2 was readily detected starting from a cell voltage of -0.54 V, suggesting an early onset considering the equilibrium voltage of -0.76 V (30).
  • the H2O2 selectivity was maintained above 90% across the whole cell voltages, reaching upto a maximum of 95% (Fig. 1 IB).
  • H2O2 generation current of ⁇ 30 mA/cm 2 (0.53 mmol/cm 2 h) can be obtained under 0 V (no external energy input), indicating an energy-efficient route compared to traditional anthraquinone or direct synthesis methods.
  • 0 V no external energy input
  • only 0.61 V cell voltage was required to deliver a significant current density of 200 mA/cm 2 with a high H2O2 FE of ⁇ 90%.
  • This large current represents an H2O2 generation rate of 3.37 mmol/cm 2 h, or 3660 mol kgcat-1 h-1 considering both cathode and anode catalyst, setting up a new productivity benchmark in both direct synthesis and electro synthesis of H2O2 (Table 1 and Figs.
  • H2O2 FEs for cell using anion conducting solid-electrolyte is probably caused by the self-decomposition of H2O2 in the solid electrolyte layer as significant gas bubbles observed, as the anion conducting solid-electrolyte provides a high alkaline environmental for ion-conduction.
  • the produced H2O2 concentration from the electrosynthesis cell can reach up to ⁇ 1.7 wt.% with an overall cell current of 800 mA (4 cm 2 electrode).
  • an overall cell current of 800 mA (4 cm 2 electrode) By speeding up or slowing down the DI water flow rate while maintaining the H2O2 generation current, a wide range of product concentrations may were obtained which could satisfy different application scenarios (Fig. 11C).
  • Up to 20 wt.% (200,000 ppm) concentrated pure H2O2 solutions can be directly and continuously obtained via electrochemical synthesis.
  • the concentrated H2O2 solution in the solid electrolyte layer 1) may self-decompose into O2 and H2O during the present quantification process; 2) may thermodynamically retard the 2e -ORR while the selectivity of the competing 4e- pathway picks up; and 3) may diffuse across the CEM and become oxidized on the anode side as frequently observed in methanol or formic acid fuel cells.
  • ICP-OES inductively coupled plasma atomic emission spectroscopy
  • Table 2 Shows the concentration of impurities for generated H2O2 using
  • H2O2 is one of the most important drinking water supply for much of the world’s population, which however may contain contaminates such as bacteria, or small organic molecules particularly in industrial area, such as Houston.
  • H2O2 is safe to both human health and environments when disinfecting bacteria and decomposing organics. Specifically, it is capable of removing total organic carbon (TOC) contaminants in rainwater for drinking.
  • TOC total organic carbon
  • the generated H2O2 stream (200 mA/cm 2 , 4 cm 2 electrode, 27 mL/h DI water flow) was directly mixed with the rainwater stream with a tunable feeding rate to optimize the purification efficiency.
  • the TOC of the pristine rainwater collected in Houston was detected to be ⁇ 5 ppm, which is above the Texas treated water standard of ⁇ 2 ppm.
  • the TOC was gradually decreased when the rainwater feeding rate was slowed down, demonstrating the efficacy of H2O2 in water treatment.
  • a maximal processing rate of 2180 L/(m 2 electrode hr) was achieved in bringing down the TOC level to meet the drinking water standards, making the design appealing for practical rainwater treatment when scaled-up.
  • the electrode area was extended from 4 cm 2 used for performance evaluation to ⁇ 80 cm 2 in one unit modular cell (Figs. 19B to D), which can be further stacked in the future for scaled up capacities.
  • a maximal cell current of over 20 A was achieved, with a high H2O2 selectivity of ⁇ 80% and production rate of ⁇ 0.3 mol/h.
  • the scaled-up device is also capable of producing highly concentrated pure H2O2 solutions up to 20 wt.% under a DI flow rate of 5.4 mL h-1 (Fig. 19D and Fig. 16B).
  • an electrosynthesis cell may produce highly pure, concentrated H2O2 with high current efficiency (95-95 %).
  • Pure oxygen or oxygen in air can be directly reduction into H2O2 at the cathode using an oxidized carbon material.
  • water may be oxidized into oxygen at the anode using IrC /C catalyst. Then, the anode O2 can be feed back to the cathode to produce H2O2 in order to enhance the overall electricality-to-PhC efficiency of the device.
  • the 4 cm 2 device can be easily scaled up to a 100 cm 2 unit module for ultra-concentrate pure H2O2 production.
  • a maximal 20 A current can be achieved using the unit module with high H2O2 selectivity (> 90%)
  • concentrated H2O2 can be obtained.
  • commercial-level 3-20wt% pure H2O2 can be continuously produced using the presently disclosed electrosynthesis cell and process.
  • the present design for a three-compartment electrolytic cell device can be further extended to other electrocatalytic synthesis of pure products beyond H2O2, such as CO2 reduction, N2 reduction and so on.
  • Figure 20A plots the CO2RR activity of 2D-Bi//solid-electrolyte//Ir0 2 -C cell with different types of solid ion-conductors.
  • H + conductor the overall current density can reach to over 100 mA/cm 2 at a cell voltage of 3.27 V, while the HCOO conductor delivers a relatively lower current of 50 mA/cm 2 at ca. 3.47 V. No other liquid products were observed except HCOOH by 1H and 13C NMR.
  • a peak HCOOH FE of 93.1% with a partial current of 32.1 mA/cm 2 was achieved under 3.08 V (Fig.
  • the decreased HCOOH FEs with increased HCOOH concentrations might be due to two reasons: the concentrated HCOOH solution in the solid electrolyte channel 1) may thermodynamically lower the C0 2 -to- HCOOH conversion rate; and 2) can crossover the Nafion film and get oxidized by anode which has been typically observed in direct formate fuel cells 49. It was found that if the Nafion 1110 (254 pm) CEM was used instead of Nafion 117 (183 pm), then a higher HCOOH FE can be achieved.
  • HCOOH FE 40.3% was obtained at 100 mA/cm 2 under 0.6 mL h- 1 DI rate for Nafion 117, while 51.1% HCOOH FE is achieved for Nafion 1110 under the same condition. It is also worthwhile to note that the improvement of HCOOH FE is still limited even when a thicker CEM (254 vs. 183 pm) was employed to block the HCOOH crossover. Thus, the concentrated HCOOH solution in the solid electrolyte layer may also thermodynamically lower the C0 2 -to-HCOOH conversion rate.
  • an inorganic solid proton conductor like insoluble Cs x H3- x PWi2O40, can also be employed for pure HCOOH generation, significantly expanding the application range of solid electrolyte design.
  • a Cu catalyst was selected, which can generate multiple C2 + oxygenate fuels. Based on the Cu catalyst derived from commercial C 3 ⁇ 4 0 nanoparticles, it was found that electrolyte-free dense C2 + oxygenate fuels, including ethanol, acetic acid, and n-propanol can be efficiently collected (Fig. 20E). At 3.45 V, the electrolyte-free oxygenates solution was obtained containing 4.6 mM ethanol, 3.4 mM n-propanol and 1.3 mM acetic acid.
  • This solid electrolyte electrochemical cell can offer a 100% atom utilization without byproduct for HCOOH production using CO2 and 3 ⁇ 4 as feedstocks (CO2 + 3 ⁇ 4 HCOOH).
  • Fig. 22B displays the current-voltage profile of the direct electrocatalytic CO2 hydrogenation cell for HCOOH vapor generation. A peak HCOOH FE of 83.3% was obtained at only 1.1 V.
  • HCOOH FE HCOOH FE of 73.36%
  • HCOOH FE 73.36%
  • the formed HCOOH can be detected at as low as 0.45 V, translating to a small cell overpotential of only 0.26 V.
  • Example 11 Electrocatalytic Characterization of Single Atom TM-CNT Catalyst
  • Fe-CNT presents the strongest H2O2 generation performance evaluated by RRDE, with a maximal H2O2 selectivity of more than 95%, and a high potential of 0.822 V vs. RHE to deliver a 0.1 mA cm -2 H2O2 onset current, as showin in Fig. 23B.
  • This early onset is superior to the so-far reported H2O2 catalysts such as Pd-Hg, Au-Pd, Pt single atoms, and highly oxidized CNTs, representing a facile ORR kinetics with negligible overpotential for C -to- H2O2 conversion.
  • Figs. 24A-B show the effects of Fe atom loading at respective amounts of 0, 0.05, 0.1, and 0.2 at% on H2O2 activity and selectivity. Compared to bare CNT, the performance was gradually increased with the increase of Fe atom loading, but dramatically dropped once Fe clusters was formed demonstrating the critical role of atomically dispersed Fe.
  • Fe-CNT maintains its high H2O2 selectivity and activity when applied onto a GDF
  • the reaction pathway can also be tuned by maintaining the metal center while switching its neighboring metalloid coordination, which combined with the corresponding changes in catalytic performances, could further reveal the possible active coordination motifs for H2O2 generation.
  • the H2O2 selectivity of Fe-CNT was decreased to a maximum of 60% when the catalyst was annealed in forming gas with Fe-C-0 coordination reduced (Red. Fe-CNT); the 4c ORR pathway was preferred when O was replaced with N to form Fe-C-N coordination, with the electron transfer number boosted from 2.09 of Fe-CNT to 3.71 of Fe-N-CNT, and even to 3.90 when the mass loading was increased to a typical fuel cell test condition.
  • Example 12 Water Disinfection by FT-CNT Catalyst
  • the generation of protons by water oxidation on the anode side is provided in order to produce pure formic acid using the above proposed solid electrocatalytic cell.
  • the electrocatalytic water oxidation in acidic solution is challenging.
  • Alternative embodiments of the present application may include a four-component electrosynthesis cell where the SE is separated by a bipolar membrane.
  • the anode may be prepared by coating a GDL electrode with a nickel iron layered double hydroxide (NiFe-LDH) as the OER catalyst and KOH electrolyte to decrease the catalyst cost and anode overpotential.
  • NiFe-LDH nickel iron layered double hydroxide
  • GDLs and the porous SSE-50 solid ion conductors were employed to separate the cathode and anode compartments, which dissociates water in into H + and OH during CO2 reduction.
  • Example 14 Carbon Catalyst Comprising Non-metal Dopants.
  • the trade-off between high activity and high selectivity in carbon materials is tested by introducing non-metal dopants, and to see demonstrate how the induced electronic structural changes can enhance the catalysts’ 2e ORR activity under large currents while maintaining high selectivity towards H2O2.
  • a series of nonmetal dopants including but not limited to boron, nitrogen, phosphorous and sulfur, were anchored on carbon black substrates, and the result catalysts were compared together with th-annealed pristine carbon black (Pure C) as the control sample. Samples were prepared in accordance with methods described above.
  • boron-doped carbon (B-C) showed the best intrinsic activity while maintaining high selectivity in both alkaline and neutral conditions from rotation ring-disk electrode (RRDE), as show in Figs. 30C-D, with a positive onset of 0.79V and 0.42V (vs. RHE) in 0.1M KOH and 0.1M Na 2 S0 4 , respectively (Figs. 30A-B).
  • Figs. 31A-B show I-V curve data plots for Pure C, B-C and O-C in 1M KOH and 1M
  • Figs. 31C-D further show FE and H2O2 partial currents measured in 1M KOH and 1M Na 2 S0 4 . Note that all the I-V curves and faradaic efficiency were taken average of 2-3 independent tests for each of the samples.
  • B-C showed improved kinetics compared to oxidized carbon (O-C), while maintaining comparably high selectivity in contrast to Pure C, in both alkaline and neutral electrolytes.
  • the B-C sample is shown to efficiently generate pure H2O2 production using the three-compartment solid-electrolyte cell configuration demonstrated above.
  • the boron doped sample can achieve a high faradaic efficiency (FE) of over 87% within a broad potential window until the current density reaches as high as 400mA cm 2 , as shown in Fig. 32A.
  • FE faradaic efficiency
  • a high production rate of 7.36 mmol cm 2 h 1 was achieved at 500mA cm 2 (Fig. 32B) and the cell is capable of operating for 30 hours without performance decay (Fig. 32C).
  • Example 15 Dual CEM in Three Component Electrosynthesis Cell
  • AEM cathode anion exchange membrane
  • H 2 O 2 at the cathode Cathode: O 2 + 2e + 2H + H 2 O 2 .
  • the water will be electrochemically oxidized into O 2 , while simultaneously releasing protons (Anode: H 2 O - 4e- O 2 + 4H + ).
  • the protons as the electrical carriers, will move across the CEMs and the porous solid-electrolyte layer to compensate the charge. Since the locally generated H 2 O 2 molecules at the CEM and cathode catalyst interface have a relatively high concentration, they will then chemically and/or electro-osmotically diffuse into the middle solid electrolyte layer, and be further carried out by the water flow as pure H 2 O 2 solution streams.
  • the CEM provides an extremely acidic environment for ORR.
  • the catalyst tested included metal and non-metal doped carbon catalysts to demonstrate this concept.
  • a nitrogen doped carbon supported nickel single atom Ni-N-C was used as the catalyst for 2e -ORR in this CEM//solid electrolyte//CEM device.
  • the Ni-N-C single atom catalyst can deliver a stable H 2 O 2 Faradic efficiency (FE) of cci. 30% under 20 mA cm 2 at least for 150 hours.
  • the concentration of generated H 2 O 2 stream was -560 ppm under 20 mA cm 2 current density.

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Abstract

L'invention porte sur une cellule d'électrosynthèse à électrolyte solide poreux et sur un procédé associé correspondant pour la synthèse directe de produits liquides de haute pureté, la cellule d'électrosynthèse comprenant un compartiment de cathode contenant une électrode de cathode comportant une couche de diffusion de gaz chargée avec un électrocatalyseur de réaction de réduction sélective pour des réactions de réduction spécifiques. La cellule d'électrosynthèse comprend en outre un compartiment d'anode contenant une électrode d'anode contenant une couche de diffusion de gaz chargée avec un catalyseur pour des réactions d'oxydation; et un compartiment d'électrolyte solide comprenant un électrolyte solide poreux; une membrane conductrice de cations; et une membrane conductrice d'anions; (ou deux membranes conductrices de cations) le compartiment d'électrolyte solide étant séparé de la cathode et de l'anode par la membrane conductrice d'anions et la membrane conductrice de cations (ou par les deux membranes conductrices de cations).
EP20761367.0A 2019-07-15 2020-07-15 Procédé de synthèse électrocatalytique efficace de solutions de produits liquides purs comprenant h2o2, des composés oxygénés, de l'ammoniac, etc Pending EP3999673A1 (fr)

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WO2019051432A1 (fr) 2017-09-10 2019-03-14 Space Arena, Inc. Enceintes pour faciliter des activités dans l'espace, ainsi que systèmes et procédés associés
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KR102702526B1 (ko) * 2020-05-22 2024-09-03 에이에스엠 아이피 홀딩 비.브이. 과산화수소를 사용하여 박막을 증착하기 위한 장치
CN112858427B (zh) * 2021-01-26 2022-03-08 暨南大学 一种镍单原子锚定碳氮材料修饰电极及其制备方法与应用
CN113020614B (zh) * 2021-02-26 2022-09-02 中国科学技术大学 铜基单原子合金催化剂及其制备方法、应用、二氧化碳电还原制备甲酸的膜电极电解质电池
CN113122869A (zh) * 2021-03-10 2021-07-16 西南科技大学 一种连续流电催化合成氨装置及电催化合成氨的方法
KR102544235B1 (ko) * 2021-03-12 2023-06-16 포항공과대학교 산학협력단 고체전해질 기반 광전기화학적 순수 과산화수소 추출을 위한 광전기화학 셀, 그의 제조방법 및 그를 이용한 과산화수소의 제조방법
CN113668001A (zh) * 2021-07-27 2021-11-19 北京化工大学 析氢反应催化剂用于电催化硝酸根还原合成氨的方法
CN113416966B (zh) * 2021-07-30 2023-09-22 联科华技术有限公司 一种电催化制备过氧化氢的单原子催化剂、制备方法及其应用
CN113526646B (zh) * 2021-08-20 2022-04-05 中南大学 一种阴/阳极原位产双氧水的电芬顿体系及其在强化有机污染物降解中的应用
CN113943947B (zh) * 2021-09-28 2022-11-15 浙江工业大学 一种用于电化学还原二氧化碳复合薄膜电极及其制备方法
CN114249388A (zh) * 2021-12-06 2022-03-29 电子科技大学长三角研究院(湖州) 一种用于高级氧化降解有机物的电解池装置及其应用
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WO2023201039A1 (fr) * 2022-04-14 2023-10-19 William Marsh Rice University Capture et récupération électrochimiques de dioxyde de carbone dans un système de réacteur à électrolyte solide
CN114717580A (zh) * 2022-05-06 2022-07-08 哈尔滨工业大学 一种原位制备过氧化氢干雾的消毒装置及其运行方法
CN114774978B (zh) * 2022-05-10 2024-04-09 浙江工业大学 一种Ni-Fe MMO薄膜修饰的泡沫镍催化剂及其制备方法和应用

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