Efficient electroreduction of CO2 by single-atom catalysts two-dimensional metal hexahydroxybenzene frameworks: A theoretical study

Electrochemical CO2 reduction provides a feasible technology for alleviating the energy crisis and global warming, as well as sustainable production of fuels. However, a tremendous challenge is to explore the highly efficient catalysts. Herein, on the basis of density functional theory (DFT) calculations, the catalytic performance of a series of M3(hexahydroxybenzene)2 (M3(HHB)2) complex nanosheets as the CO2 reduction reaction (CO2RR) catalysts was systemically evaluated. The results demonstrated that the catalytic activity of M3(HHB)2 depends on the intensity of interaction between CO2RR intermediates and metal atoms, and can be adjusted by changing the metal atoms. Among the studied candidates, M3(HHB)2 (M = Cr, Mo, Ru, and Rh) are predicted to be potential electrocatalysts toward the CO2RR due to low limiting potential of -0.49, -0.67, -0.63, and -0.68 V, respectively, which are comparable to that of other reported CO2RR catalysts. In particular, CH4 is the favorable product on M3(HHB)2 (M = Cr and Mo) via *HCOO pathway, while the main product of M3(HHB)2 (M = Ru and Rh) is CH3OH via *COOH channel. It is expected that our investigations could provide meaningful guidance for developing CO2RR electrocatalysts.