反应条件对铜催化CO2电还原的影响

工业规模的化石能源消耗导致大气中二氧化碳含量不断增加,CO₂转化利用成为人们日益关注的热点问题. 金属铜因其成本低廉、储量丰富,并且具有独特的CO₂亲和力能够生成多碳化合物,是目前CO₂电还原中研究最为广泛深入的电极材料. 由于阴、阳离子的特征吸附对Cu电极性能有显著影响,并且不同反应体系中对Cu电极上CO₂吸附、活化影响也有所不同,因此导致金属Cu电极上报道的电催化活性、产物种类与选择性等都非常宽泛. 基于此,有必要系统地研究各种反应条件对金属Cu电极电催化CO₂还原性能的影响. 作者选择了平均粒径为600 nm的商品化金属Cu颗粒作为电还原CO₂的催化剂,研究了不同反应条件包括各种常用电解质溶液、KHCO₃的浓度以及H型电解池和流动池. 实验结果表明,浓度为0.5 mol·L ^-1的KHCO₃作为电解质溶液具有较好催化活性和较高的产物分电流密度,流动池可以进一步提高主要产物甲酸盐和CO的分电流密度. 本研究工作从反应条件的角度对CO₂还原的电催化转化进行了系统研究,有助于理解电解液和反应器等因素对CO₂电还原反应过程的影响规律.

Effect of Reaction Conditions on Cu?Catalyzed CO2 Electroreduction

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.