期刊
ACS CATALYSIS
卷 11, 期 8, 页码 4920-4928出版社
AMER CHEMICAL SOC
DOI: 10.1021/acscatal.1c00415
关键词
electrocatalysis; transition-metal carbides; electrochemical CO2 reduction; surface Pourbaix diagram; ab initio thermodynamics; solid/liquid interface; XPS; HER
资金
- Austrian Science Foundation (FWF) [I-4114]
- Alexander von Humboldt (AvH) foundation
- Austrian Research Promotion Agency (FFG) [870523]
- Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy [EXC 2089/1-390776260]
- FWF [J4278]
- Austrian Science Fund (FWF) [J4278] Funding Source: Austrian Science Fund (FWF)
In aqueous electrolytes, surface oxide formation on hexagonal Mo2C completely suppresses CO2 activation, while in nonaqueous electrolytes, Mo2C shows CO2RR activity when protected from ambient air.
Compound materials, such as transition-metal (TM) carbides, are anticipated to be effective electrocatalysts for the carbon dioxide reduction reaction (CO2RR) to useful chemicals. This expectation is nurtured by density functional theory (DFT) predictions of a break of key adsorption energy scaling relations that limit CO2RR at parent TMs. Here, we evaluate these prospects for hexagonal Mo2C in aqueous electrolytes in a multimethod experiment and theory approach. We find that surface oxide formation completely suppresses the CO2 activation. The oxides are stable down to potentials as low as -1.9 V versus the standard hydrogen electrode, and solely the hydrogen evolution reaction (HER) is found to be active. This generally points to the absolute imperative of recognizing the true interface establishing under operando conditions in computational screening of catalyst materials. When protected from ambient air and used in nonaqueous electrolyte, Mo2C indeed shows CO2RR activity.
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