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CN-121974395-A - Preparation method and application of single-layer assembled bismuth subcarbonate nanosheet catalyst precursor

CN121974395ACN 121974395 ACN121974395 ACN 121974395ACN-121974395-A

Abstract

The invention relates to a preparation method and application of a single-layer assembled bismuth subcarbonate nano-sheet catalyst precursor, which comprises the steps of 1) dissolving bismuth salt in water, adding triethanolamine, stirring and mixing to form a uniform white solution, 2) adding alkaline substances into the solution obtained in the step 1), adjusting the solution to be alkaline, 3) heating the solution obtained in the step 2) to react to obtain a suspension containing white bismuth subcarbonate nano-sheets, 4) carrying out solid-liquid separation on the suspension obtained in the step 3), collecting white solid products, washing and drying to obtain the single-layer assembled bismuth subcarbonate nano-sheet precursor, wherein the morphology of the single-layer assembled bismuth subcarbonate nano-sheet precursor is formed by sequentially assembling small-size nano-sheets along a two-dimensional plane direction, the stacking and aggregation of nano-sheets can be effectively inhibited, and the exposure and the structural stability of effective active sites are remarkably improved. The method is applied to the field of electrochemical carbon dioxide reduction, and can continuously run for 300 hours under the current density of 100 mA cm ‑2 , and the average formic acid Faraday efficiency reaches 82.6%.

Inventors

  • DONG CUNKU
  • LOU JINGXIAN

Assignees

  • 天津大学

Dates

Publication Date
20260505
Application Date
20260209

Claims (9)

  1. 1. The preparation method of the single-layer assembled bismuth subcarbonate nano-sheet catalyst precursor is characterized by comprising the following steps: 1) Dissolving bismuth salt in water, adding triethanolamine, stirring and mixing to form uniform white solution; 2) Adding an alkaline substance into the solution obtained in the step 1), and regulating the solution to be alkaline; 3) Heating the solution obtained in the step 2) to react to obtain a suspension containing white bismuth subcarbonate nano-sheets; 4) And 3) carrying out solid-liquid separation on the suspension obtained in the step 3), collecting a white solid product, and washing and drying to obtain the single-layer assembled bismuth subcarbonate nanosheet precursor.
  2. 2. The method for preparing a monolayer assembled bismuth subcarbonate nanosheet catalyst precursor as claimed in claim 1 wherein the bismuth salt in step 1) is bismuth nitrate.
  3. 3. The method for preparing a single-layer assembled bismuth subcarbonate nano-sheet catalyst precursor according to claim 1, wherein the molar ratio of bismuth salt to triethanolamine in the step 1) is (3-5): 1.
  4. 4. The method for preparing a single-layer assembled bismuth subcarbonate nano-sheet catalyst precursor according to claim 1 wherein the alkaline material in step 2) is one or a combination of two of potassium hydroxide and sodium hydroxide.
  5. 5. The method for preparing a monolayer assembled bismuth subcarbonate nanosheet catalyst precursor according to claim 1, wherein the pH of the solution in step 2) is 10 to 14.
  6. 6. The method for preparing a monolayer assembled bismuth subcarbonate nano-sheet catalyst precursor according to claim 1, wherein the solution in the step 3) is heated at 55-75 ℃.
  7. 7. The method for preparing a monolayer assembled bismuth subcarbonate nanosheet catalyst precursor as claimed in claim 1, wherein the reaction time of step 3) is 2-3 hours.
  8. 8. The monolayer assembled bismuth subcarbonate nanosheet catalyst precursor prepared by the method of claim 1 for use in electrochemical carbon dioxide reduction.
  9. 9. The monolayer assembled bismuth subcarbonate nanosheet catalyst precursor prepared by the method of claim 1 for use in an electrochemical carbon dioxide reduction process to produce formic acid membrane electrode assembly.

Description

Preparation method and application of single-layer assembled bismuth subcarbonate nanosheet catalyst precursor Technical Field The invention belongs to the technical field of metal catalysts, and relates to a preparation method and application of a single-layer assembled bismuth subcarbonate nanosheet catalyst precursor for electrochemical carbon dioxide reduction. Background With the continuous growth of global energy demand and the acceleration of industrial processes, the long-term and large-scale use of fossil energy causes the continuous increase of the concentration of carbon dioxide (CO 2) in the atmosphere, which is one of the important causes of climate change and environmental problems. In this context, the use of renewable energy sources to convert CO 2 to high value-added chemicals is considered to be an effective way to achieve carbon resource recycling and to relieve environmental stresses. The electrochemical carbon dioxide reduction reaction utilizes electric energy to drive the reaction process, has the advantages of mild reaction conditions, strong process controllability, easy coupling with renewable energy sources and the like, and receives wide attention. The CO 2 molecule has higher thermodynamic stability, the electrochemical reduction process involves multiple electron transfer, the reaction path is complex, and various products are easy to generate, so that a high-efficiency catalyst is needed to realize the selective generation of target products. Formic acid has important application value in the fields of chemical synthesis, liquid hydrogen storage, fuel cells and the like, and becomes one of important target products in electrochemical CO 2 reduction reaction. The prior researches show that bismuth (Bi) and related materials thereof have higher product selectivity and lower reaction potential in the process of preparing formic acid by electrochemical CO 2 reduction, and show good application potential. However, in the practical application system, especially under the conditions of high current density and long-time operation, the existing bismuth-based catalyst generally has the problem of insufficient structural stability, uncontrollable structural reconstruction easily occurs in the electrocatalytic reaction process, so that the electrochemical application performance is obviously limited, the formic acid partial current density under the cell pressure of 3.5V is generally only within 40 mA cm -2, the formic acid selectivity is only between 30 and 60 percent, and the practical industrial application requirement of preparing formic acid by electrochemical carbon dioxide reduction is difficult to be met. Therefore, there is still a need for a more rational and controllable design and control of bismuth-based catalyst structures to achieve high catalytic activity, high product selectivity and long-term stability under high-strength conditions. Disclosure of Invention The invention aims to provide a preparation method of a single-layer assembled bismuth subcarbonate nano-sheet catalyst precursor. Because metallic bismuth is easy to oxidize in air and solution environment, and the two-dimensional bismuth nanosheet material with controllable morphology and stable structure is difficult to directly obtain under the conventional synthesis condition, the bismuth subcarbonate nanosheet with stable structure and easy morphology regulation is used as a catalyst precursor. The bismuth subcarbonate nano-sheet precursor is not directly used as a final catalyst, but is used as a precursor material to perform in-situ structural transformation under the electrochemical reduction condition to form metal bismuth with electrocatalytic activity, and the structural characteristics of the two-dimensional single-layer nano-sheet are reserved, so that the bismuth subcarbonate nano-sheet precursor is applied to electrochemical carbon dioxide reduction reaction. The prior researches show that the structure actually playing a catalytic role in the electrocatalytic reaction process is generally derived from in-situ reconstruction of a catalyst precursor under working conditions, and the initial morphology of the precursor has important influence on the finally formed catalyst structure, catalytic activity and product selectivity. The invention adopts a solvothermal preparation process, and can prepare the monolayer assembled bismuth subcarbonate nanosheet precursor with controllable morphology in a lower reaction temperature and a shorter reaction time. The bismuth subcarbonate nano-sheet precursor can be in-situ converted into a bismuth catalyst with a stable single-layer assembled nano-sheet structure in the electrochemical reduction process, the structure effectively inhibits stacking and aggregation among nano-sheets, exposes more effective active sites in the electrocatalytic reaction process, and is beneficial to charge transfer in a reaction interface and adsorption and stabilization of a key react