Mechanistic Understanding and Design of Non-noble Metal-based Single-atom Catalysts Supported on Two-dimensional Materials for CO2 Electroreduction

Single-atom catalysts (SACs) composing of low-cost, earth-abundant metals, with two-dimensional material supports have displayed great potential in a wide range of electrochemical reactions, including CO2 reduction reaction (CO2RR) to convert CO2 to valuable chemical and fuels. In recently years, substantial advances have been achieved in the preparation methodologies with improved catalytic performances, but the underlying structure-activity relationship from a general perspective remains elusive. Especially, it is urgent to summarize the SACs with diatom metal centers toward efficient CO2RR. Based on the recent progress, this review synopsizes the fundamental understandings of non-noble metal-based SACs for CO2RR using selected examples. We also highlight the representative molecular models from the latest progress, including M-N-C, heteroatom co-doping, vacancy/edge defect and bimetallic SACs, aiming to elucidating the nature of active sites on various 2D substrates. Moreover, we summarize the spectroscopic and computational studies to verify atomic-level regulation on geometric and electronic properties of SACs. We anticipate that this review will deepen the mechanistic understanding of the structure-performance relationship and inspire future study of SACs for CO2RR.