Electrocatalytic Reduction of Carbon Dioxide to Carbon Monoxide using Cobalt Nitride

电催化还原二氧化碳是一种潜在的解决全球变暖的途径，但是仍有许多挑战. 本文报道了使用氮化钴在水溶液中电催化还原二氧化碳为一氧化碳. 通过对比不同煅烧温度及气氛合成的催化剂表明氮掺杂对催化活性的提高至关重要. 其中700-Co5.47N/C展现了最高的催化活性，在较低的电势-0.7 V(vs. RHE)下，一氧化碳的电流密度达到9.78 mA·cm-2. 另外，通过改变电解电压，CO/H2 的比例能在1:3到3:2之间调节. 91 mV·dec-1的Tafel 斜率表明形成表面吸附的CO2·-中间体是CO2表面还原的决速步骤，而氮化策略可以增加表面碱性位点的数量，从而稳定还原的中间体，提高反应效率和产物选择性.Electrocatalytic reduction of carbon dioxide (CO2) is a promising method to alleviate global warming issues, although it still faces many challenges. Herein, we report cobalt nitride for electrocatalytic reduction of CO2 to carbon monoxide (CO) in an aqueous electrolyte. A comparison of catalysts with different preparation temperatures and atmospheres suggests that nitrogen doping is critical to improve catalytic activity. For the most active catalyst of 700-Co5.47N/C, the CO current density reached 9.78 mA·cm-2 at potential of -0.7 V vs. RHE. In addition, the CO/H2 ratio could be adjusted from 1:3 to 3:2 by changing applied potential. Tafel slope of 91 mV·dec-1 indicates that forming a surface adsorbed CO2·- intermediate became the rate-determining step and nitriding strategy increased CO2 selectivity by providing more base sites.This work was financially supported by the National Key Projects for Fundamental Research and Development of China (2016YFB0600901), and National Nature Science Foundation of China (21701180).作者联系地址：(1. 中国科学院理化技术研究所，中国科学院光化学转换与功能材料重点实验室，北京100190；2. 中国科学院大学，北京 100190；3. 天津大学化工学院, 天津 300072)Author's Address: 1. Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Beijing 100190, China;  2. University of Chinese Academy of Sciences,  Chinese Academy of Sciences, Beijing 100190, China; 3. School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China通讯作者E-mail：kang.peng@tju.edu.c