Homonuclear multi-atom catalysts for CO2 electroreduction: a comparison density functional theory study with their single-atom counterparts

The development of efficient electrocatalysts for the CO2 reduction reaction (CO2RR) is essential to mitigate global energy and environmental problems. Single-atom catalysts (SACs) have become an emerging frontier in the CO2RR because of the high utilization of noble metals, but they suffer from poor selectivity toward high-order hydrocarbons. Herein, using density functional theory calculations, we predict that homonuclear double-atom and triple-atom catalysts supported by two-dimensional Mo2CO2 exhibit superior catalytic performance for the CO2RR compared to their single-atom counterparts. We show that the multi-nuclear reaction centers on multi-atom catalysts boost the adsorption of key CO2RR intermediates, such as *HCOO and *CH, enabling selective reduction toward the CH4 product at ultralow overpotentials. Besides, C-C coupling can also be facilitated on multi-nuclear sites, which enables an efficient production of the C2H5OH product. This work lays a foundation for the future development of multi-atom catalysts for the CO2RR.