Origin of Metal–Support Interactions for Selective Electrochemical CO<sub>2</sub> Reduction into C<sub>1</sub> and C<sub>2+</sub> Products
Hengquan Chen, Wanghui Zhao, Linqin Wang, Zhong Chen, Wentao Ye, Jianyang Zang, Tao Wang, Licheng Sun, Wenxing Yang
Abstract
The design of metal–support interaction (MSI) is an essential strategy in developing classical heterogeneous catalysts and recently for electrocatalysts. Particularly, for the electrochemical CO 2 reduction reaction (CO 2 RR), metal–oxide-supported Cu catalysts have demonstrated remarkable selectivity improvements toward C 1 and C 2+ products, whereas the exact regulatory mechanism remains debated. Herein, we elucidate that the stabilization of the Cu + /Cu interface is likely the dominant mechanism for the selectivity improvement rather than the perceived formation of Cu–O–M dual sites. We designed two CeO 2 -modified Cu nanocube catalysts with a similar Cu/CeO 2 heterogeneous interface yet distinct high selectivity toward CH 4 (40 ± 1.4%) and C 2 H 4 (52 ± 0.57%), offering ideal models for in-depth mechanistic studies. In situ spectroscopy characterized a notable presence of adsorbed CO (CO ads ) at the formed Cu/CeO 2– x interface. Yet, these CO ads only account for less than 5% of the total CO ads population for both catalysts, with most CO ads remaining at the Cu/Cu + sites. Further characterization revealed a varied electronic interaction between Cu and CeO 2 for these two catalysts, generating different surface Cu + under operational conditions, which subsequently tune the CO 2 RR selectivities by regulating the surface CO ads populations. These results provide an in-depth understanding of MSI for its further utilization in the CO 2 RR and other electrocatalysis processes.