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CN-121976210-A - Proton buffer composite structure and preparation method and application thereof

CN121976210ACN 121976210 ACN121976210 ACN 121976210ACN-121976210-A

Abstract

The invention relates to a proton buffer composite structure, a preparation method and application thereof. The proton buffer composite structure disclosed by the invention is a sandwich type composite body formed by sequentially stacking electrodes, inorganic buffer coatings and diaphragms. The composite structure can delay proton conduction from the diaphragm to the cathode through the inorganic buffer coating formed by the low-cost and stable hydrophilic ultrafine powder on the premise of not damaging the activity of the catalyst, thereby realizing the proton regulation and control of an electrode-electrolyte interface and the reaction microenvironment optimization, effectively inhibiting hydrogen evolution reaction, and remarkably improving the selectivity and the efficiency of target reaction. The preparation method of the composite structure is simple and stable, and is easy for large-scale production. The membrane type electrolytic tank with the composite structure can be suitable for long-time stable operation under high current density, can be widely applied to various electrochemical reaction systems such as electrocatalytic reduction, electrosynthesis, environmental remediation and the like, and has outstanding industrial application prospect.

Inventors

  • LIU LEQUAN
  • LIAN KANG

Assignees

  • 天津大学

Dates

Publication Date
20260505
Application Date
20251231

Claims (10)

  1. 1. The proton buffer composite structure is characterized by comprising a sandwich type composite body formed by sequentially stacking an electrode, an inorganic buffer coating and a diaphragm; the electrode comprises a conductive carrier and a catalyst loaded on the conductive carrier; the inorganic buffer coating is arranged on the surface of the catalyst, is used for providing good proton buffer effect and does not directly participate in electrochemical reaction, and has the mass density range of 0.1mg/cm 2 ～5mg/cm 2 ; the membrane is arranged on the surface of the inorganic buffer coating on the side far away from the catalyst and is used for conducting protons.
  2. 2. The proton buffering composite structure of claim 1, wherein the catalyst comprises one or more of metal nanoparticles, metal compound particles, metal complex particles, nitrogen doped carbon particles, and the conductive support comprises one or more of carbon paper, carbon cloth, metal fiber felt.
  3. 3. The proton buffer composite structure according to claim 1, wherein the inorganic buffer coating comprises hydrophilic ultrafine powder of one or more of zirconium dioxide, silicon dioxide, titanium dioxide and aluminum oxide, and the average particle size of the hydrophilic ultrafine powder ranges from 10nm to 500nm.
  4. 4. The proton-buffered composite structure of claim 1, wherein the mass density of the inorganic buffer coating is in the range of 0.5mg/cm 2 ～3.5mg/cm 2 .
  5. 5. The proton buffering composite structure according to claim 1, wherein the membrane is a cation exchange membrane and/or a bipolar membrane and/or a porous membrane.
  6. 6. A method for preparing the proton-buffering composite structure according to any one of claims 1 to 5, comprising the steps of: sequentially stacking and supporting the catalyst uniformly dispersed in the solvent A and the hydrophilic ultrafine powder uniformly dispersed in the solvent B on a first matrix, and then combining the first matrix with a second matrix in a para-position manner; Or sequentially laminating and supporting the hydrophilic ultrafine powder uniformly dispersed in the solvent B and the catalyst uniformly dispersed in the solvent A on a second matrix, and then combining the first matrix in a para-position; or the catalyst uniformly dispersed in the solvent A is loaded on a first matrix, the hydrophilic ultrafine powder uniformly dispersed in the solvent B is loaded on a second matrix, and then the two parts are combined in para-position; The solvent A or the solvent B is one or a mixed solution of more of water, methanol, ethanol, isopropanol, glycol or perfluorinated sulfonic acid naphthol membrane solution.
  7. 7. The method of claim 6, wherein the supporting means comprises spraying, dipping, vapor deposition, electrodeposition or chemical vapor deposition.
  8. 8. The method for preparing a proton-buffering composite structure according to claim 6, wherein the para-position bonding mode is hot pressing or direct bonding.
  9. 9. Use of a proton-buffering composite structure according to any one of claims 1 to 5, comprising a membrane-type electrolytic cell equipped with said proton-buffering composite structure.
  10. 10. The use of a proton-buffering composite structure according to claim 9, wherein the type of electrocatalytic reaction used in the assembly of the proton-buffering composite structure membrane electrolyzer comprises electrocatalytic carbon dioxide reduction, electrocatalytic nitrogen reduction to ammonia, electrocatalytic hydrogen peroxide synthesis, electrochemical reduction to chlorine-containing organics or electrochemical reduction to heavy metal ions.

Description

Proton buffer composite structure and preparation method and application thereof Technical Field The invention relates to the field of electrochemical catalysis, in particular to a proton buffer composite structure, a preparation method and application thereof. Background In recent years, a membrane type electrolytic cell has become an important strategy for constructing a high-efficiency electrochemical reaction system, and is widely applied to the fields of electrocatalytic reduction, electrochemical synthesis, environmental remediation and the like. Among them, the membrane type electrolytic cell with proton conduction as the core is regarded as one of the core devices with the most industrialization potential by virtue of the unique high ion selectivity, low surface resistance and good stability of the membrane electrode structure. Although such membrane electrode technology has grown mature, it has always faced a challenge in catalytic reactions involving proton-coupled electron transfer as a critical step, where protons are both the charge carriers and reactants necessary for the target reaction and the primary source of inducing competing hydrogen evolution side reactions. The essence of this contradiction is that traditional membrane electrode structures of this type are intended to face the cathode for efficient, low-resistance proton conduction, but lack active and effective regulation of local proton concentration at the electrode-electrolyte interface and its mass transfer kinetics. Particularly, with the increase of the applied current density, the proton concentration at the interface is changed drastically, and the hydrogen evolution side reaction takes absolute advantage in thermodynamics and kinetics, so that the selectivity and the energy efficiency of the target reaction path are severely restricted. In particular to the technical field of electrocatalytic carbon dioxide (CO 2) reduction, membrane type electrolytic cells based on proton conduction (cation exchange membrane, bipolar membrane) have made a certain progress in the CO 2 capturing electrolytic system. However, the cathode in such devices is usually in direct contact with the ion exchange membrane, which is very prone to cause excessive protons on the surface of the catalyst under the action of an external electric field, thereby causing serious hydrogen evolution side reactions and affecting the selectivity of the CO 2 electroreduction product. To enhance the electrolysis performance of CO 2, existing proton buffering techniques, such as modifying ionic polymers, inhibit hydrogen evolution side reactions by forming a positive charge layer on the catalyst surface to repel protons (e.g., in the literature under the english name ：Efficient Bicarbonate Electrolysis to Formate Enabled via Ionomer Surface Modification in Cation Exchange Membrane Electrolyzers, where the literature is entitled: efficient bicarbonate electrolysis formate preparation by ion exchange membrane surface modification in ion exchange membrane electrolyzer (Xing et al, angel. Chem. Int. Ed.,2025, e 202504835). The technology has great challenges in practical application due to the high cost of the ionic polymer. Another prior art is the provision of a mixed cellulose ester filter membrane between the electrode and the separator (e.g., as described in the literature under the english name: CO 2 electroreduction to multicarbon products from carbonate capture liquid, where the name: preparation of a multi-carbon product by electroreduction of carbon dioxide from a carbonate capture solution (Lee et al, joule,2023,7,1277-1288). The filter membrane is a porous membrane obtained by esterification reaction of cellulose, and is used for increasing the physical distance between an electrode and a diaphragm and delaying proton conduction. However, the technology works with a large physical distance (64-540 μm, 130 μm being the best performance), which results in high cell pressure and high reaction energy consumption of the electrolyzer. In addition, the filter membrane has poor chemical stability and is prone to structural failure during long-term electrolysis. In view of the foregoing, there is a need in the art for an economical composite membrane-electrode structure that can operate for a long period of time and stably, and that can achieve active management of protons at the electrode-electrolyte interface by regulating the proton conductivity. Disclosure of Invention The invention aims to solve the technical problem that in an electrochemical device based on proton conduction, the whole and passive proton conduction process causes the problem that the selectivity of a target product is low in the catalytic reaction generated at a cathode. In particular, in an electrolysis system for capturing CO 2, the invention aims to solve the technical problems of high cost of ionic polymer, poor chemical stability of a mixed cellulose ester filter membrane, easy structural fa