关键词: 二氧化碳电还原, 铜催化剂, 反应条件, 气体扩散电极

Abstract:

Electrochemical conversion of carbon dioxide (CO₂) driven by renewable electricity that can meet both carbon emission reduction and renewable energy utilization has been rapidly developed in recent years. Copper (Cu) catalyst has long been a promising candidate for CO₂ electroreduction applications because of its natural abundance and specific capability of producing a substantial amount of C2 products. However, various metallic Cu electrodes reported have been significantly influenced by the adsorption of certain cation/anion ions, resulting in wide-span catalytic activities and selectivity for various products. In addition, a recent report demonstrated that by virtue of gas-diffusion flow cell with Cu cathode, remarkable ethylene production was achieved in CO₂ electroreduction. It is, therefore, desirable to systematically investigate the effect of reaction conditions on the performances of Cu-catalyzed CO₂ electroreduction. Here we chose the commercial Cu particles with an average size of 600 nm as the catalyst for CO₂ electroreduction and investigated the electrocatalytic performances under various reaction conditions, including the commonly used electrolyte solutions, the different potassium hydrogen carbonate (KHCO3) concentrations, as well as H-type and gas-diffusion flow cells. The results of linear sweep voltammetry and potentiostatic CO₂ electrolysis showed that KHCO₃ as an electrolyte solution with a concentration of 0.5 mol?L^-1 offered good catalytic activities and high current densities, and the gas-diffusion flow cell could further improve the Faradaic efficiencies and partial current densities of the main products formate and CO. This work provides a fundamental insight to the electrocatalytic conversion of CO₂ reduction from the view of reaction conditions.

Key words: CO₂ electroreduction, copper catalyst, reaction conditions, gas-diffusion electrode