Electrochemical Reduction of CO to CO over Transition Metal/N-Doped Carbon Catalysts: The Active Sites and Reaction Mechanism.

Electrochemical CO reduction to value-added chemicals/fuels provides a promising way to mitigate CO emission and alleviate energy shortage. CO -to-CO conversion involves only two-electron/proton transfer and thus is kinetically fast. Among the various developed CO -to-CO reduction electrocatalysts, transition metal/N-doped carbon (M-N-C) catalysts are attractive due to their low cost and high activity. In this work, recent progress on the development of M-N-C catalysts for electrochemical CO -to-CO conversion is reviewed in detail. The regulation of the active sites in M-N-C catalysts and their related adjustable electrocatalytic CO reduction performance is discussed. A visual performance comparison of M-N-C catalysts for CO reduction reaction (CO RR) reported over the recent years is given, which suggests that Ni and Fe-N-C catalysts are the most promising candidates for large-scale reduction of CO to produce CO. Finally, outlooks and challenges are proposed for future research of CO -to-CO conversion.