Role of Surface Hydrogen Coverage in C–C Coupling Process for CO<sub>2</sub> Electroreduction on Ni-Based Catalysts
Haowen Ding, Shisheng Zheng, Xinzhe Yang, Junjie Pan, Zhefeng Chen, Mingzheng Zhang, Shunning Li, Feng Pan
Abstract
Research into electrochemical CO 2 reduction reaction (CO 2 RR) toward multicarbon products has long been dominated by the investigation of Cu-based catalyst system. Yet, several recent studies have documented competitive catalytic performance on Ni-based alloys and compounds, which can trigger C–C coupling for producing long-chain hydrocarbons. To develop an in-depth understanding of how Ni-based catalysts carry out C–C coupling, here we present a comparative study of Ni metal and Ni 3 Ga via density functional theory calculations. Inspiringly, unlike Ni metal where the distribution of hydrogen adsorbates on the surface is found irregular during CO 2 RR, Ni 3 Ga exhibits a perfectly ordered distribution pattern of surface hydrogen at a low coverage when CO 2 is reduced into intermediates ready for C–C coupling. This difference in adsorbate coverage leads to scenarios in which neighboring CO 2 RR intermediates on Ni metal tend to be separated by a large distance, whereas they can be accommodated much closer on Ni 3 Ga surface, thus creating the opportunity for the coupling reaction. This mechanistic insight finds support from previous experimental reports, and can establish surface hydrogen coverage as a nonnegligible factor for C–C coupling on Ni-based catalysts.