Microenvironmental Feeding and Stabilization of C2H4 Intermediates by Iodide-Doped Copper Nanowire Arrays to Boost C2H6 Formation

• Published in: Energy & fuels Vol. 35; no. 19; pp. 15987 - 15994
• Main Authors: Xiang, Kaisong, Liu, Yucheng, Li, Chaofang, Liu, Xudong, Yi, Huimin, Wu, Lin, Shen, Fenghua, Liu, Min, Wang, Pingshan, Liu, Hui
• Format: Journal Article
• Language: English
• Published: American Chemical Society 07.10.2021
• Subjects: Environmental and Carbon Dioxide Issues
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.1c02616

The electroreduction of CO2 provides an attractive routine to produce hydrocarbons as an alternative of traditional petroleum chemical methods, as well as cobenefits the approach of CO2 emission control. Among various C2 hydrocarbons, C2H6 has the highest energy density but poor selectivity in CO2 electroreduction. Thus, the development of highly active catalysts and formation mechanism is desired. Herein, a facile method to synthesize iodide-doped Cu nanoarray (ID-Cu NA) catalysts and a strategy to boost C2H6 electrosynthesis was developed. ID-Cu NAs have dispersive iodide dopants on nanowires, which create a microenvironment to feed, stabilize, and hydrogenate C2H4. This catalyst displays a remarkable selectivity for C2H6 production. Impressively, ID-Cu NAs show a Faradaic efficiency of 24% for C2H6, five times higher than the corresponding Cu NAs before iodide doping. However, the Faradaic efficiency of C2H4 on Cu NAs decreases from 28 to 5% after iodide doping. The results of C2H4 electrodesorption and electrohydrogenation tests indicated that the iodide dopant contributed a more stable C2H4 adsorption and higher hydrogenation ability. Density functional theory calculations demonstrated that the doping of iodide helps to strengthen the adsorption of C2H4 on the Cu surface and lowers the energy barrier of the hydrogenation to C2H6, which simultaneously encourages C2H6 formation in CO2 electroreduction. This work also cleared up the origin of C2H6 formation in CO2 reduction reaction (CO2RR) in which a tandem pathway from CO2 → C2H4 to C2H4 → C2H6 is involved.