Electrocatalysis represents a promising method to generate renewable fuels and chemical feedstock from the carbon dioxide reduction reaction (CO2RR). However, traditional electrocatalysts based on transition metals are not efficient enough because of the high overpotential and slow turnover. MXenes, a family of two-dimensional metal carbides and nitrides, have been predicted to be effective in catalyzing CO2RR, but a systematic investigation into their catalytic performance is lacking, especially on hydroxyl (–OH) terminated MXenes relevant in aqueous reaction conditions. In this work, we utilized first-principles simulations to systematically screen and explore the properties of MXenes in catalyzing CO2RR to CH4 from both aspects of thermodynamics and kinetics. Sc2C(OH)2 was found to be the most promising catalyst with the least negative limiting potential of -0.53 V vs. RHE. This was achieved through an alternative reaction pathway, where the adsorbed species are stabilized by capturing H atom from the MXene’s OH-termination group. New scaling relations, based on the shared H interaction between intermediates and MXenes, were established. Bader charge analyses reveal that catalysts with less electron migration in the *(H)COOH → *CO elementary step exhibit better CO2RR performance. This study provides new insights regarding the effect of surface functionalization on the catalytic performance of MXenes to guide future materials design.
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Q.F.Z. was supported by National Key Research and Development Program of China (No. 2017YFB0702100), Beijing Natural Science Foundation (2192029) and Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Human Resources and Social Security of China. Z.W.S. was supported by the Singapore
National Research Foundation (NRF-NRFF2017-04). D. L. is supported by the European Regional Development Fund in the IT4Innovations national supercomputing center - path to exascale project, project number CZ.02.1.01/0.0/0.0/16_013/0001791 within the Operational Programme Research, Development and Education, grant No. 17-27790S of the Czech Science Foundation, Mobility grant No. 8J18DE004 and SGS
No. SP2019/110.