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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]

Metal‐organic framework catalysts bring new opportunities for CO2 electrocatalysis. Herein, we first conduct density‐functional theory calculations and predict that Co‐based porphyrin porous organic layers (Co‐PPOLs) exhibit good activity for CO2 conversion because of the low *CO adsorption energy at Co‐N4 sites, which facilitates *CO desorption and CO formation. Then, we prepare two‐dimensional Co‐PPOLs with exclusive Co‐N4 sites through a facile surfactant‐assisted bottom‐up method. The ultrathin feature ensures the exposure of catalytic centers. Together with large specific area, high electrical conductivity and CO2 adsorption capability, Co‐PPOLs achieve a peak faradaic efficiency for CO production (FECO=94.2 %) at a moderate potential in CO2 electroreduction, accompanied with good stability. Moreover, Co‐PPOLs reach an industrial‐level current above 200 mA in a membrane electrode assembly reactor, and maintain near‐unity CO selectivity (FECO>90 %) over 20 h in CO2 electrolysis. [ABSTRACT FROM AUTHOR]

Polymer electrolyte membrane water electrolysis (PEMWE) has been regarded as a promising technology for renewable hydrogen production. However, acidic oxygen evolution reaction (OER) catalysts with long‐term stability impose a grand challenge in its large‐scale industrialization. In this review, critical factors that may lead to catalyst's instability in couple with potential solutions are comprehensively discussed, including mechanical peeling, substrate corrosion, active‐site over‐oxidation/dissolution, reconstruction, oxide crystal structure collapse through the lattice oxygen‐participated reaction pathway, etc. Last but not least, personal prospects are provided in terms of rigorous stability evaluation criteria, in situ/operando characterizations, economic feasibility and practical electrolyzer consideration, highlighting the ternary relationship of structure evolution, industrial‐relevant activity and stability to serve as a roadmap towards the ultimate application of PEMWE. [ABSTRACT FROM AUTHOR]