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Electrochemical CO2 reduction to value‐added chemicals or fuels offers a promising approach to reduce carbon emissions and alleviate energy shortage. Cu‐based electrocatalysts have been widely reported as capable of reducing CO2 to produce a variety of multicarbon products (e.g. ethylene and ethanol). In this work, we develop sulfur‐doped Cu2O electrocatalysts, which instead can electrochemically reduce CO2 to almost exclusively formate. We show that a dynamic equilibrium of S exists at the Cu2O‐electrolyte interface, and S‐doped Cu2O undergoes in situ surface reconstruction to generate active S‐adsorbed metallic Cu sites during the CO2 reduction reaction (CO2RR). Density functional theory (DFT) calculations together with in situ infrared absorption spectroscopy measurements show that the S‐adsorbed metallic Cu surface can not only promote the formation of the *OCHO intermediate but also greatly suppress *H and *COOH adsorption, thus facilitating CO2‐to‐formate conversion during the electrochemical CO2RR. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction to value‐added chemicals/fuels provides a promising way to mitigate CO2 emission and alleviate energy shortage. CO2‐to‐CO conversion involves only two‐electron/proton transfer and thus is kinetically fast. Among the various developed CO2‐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 CO2‐to‐CO conversion is reviewed in detail. The regulation of the active sites in M‐N‐C catalysts and their related adjustable electrocatalytic CO2 reduction performance is discussed. A visual performance comparison of M‐N‐C catalysts for CO2 reduction reaction (CO2RR) 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 CO2 to produce CO. Finally, outlooks and challenges are proposed for future research of CO2‐to‐CO conversion. [ABSTRACT FROM AUTHOR]