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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]

Single‐atom catalysts (SACs) show great promise for electrochemical CO2 reduction reaction (CRR), but the low density of active sites and the poor electrical conduction and mass transport of the single‐atom electrode greatly limit their performance. Herein, we prepared a nickel single‐atom electrode consisting of isolated, high‐density and low‐valent nickel(I) sites anchored on a self‐standing N‐doped carbon nanotube array with nickel–copper alloy encapsulation on a carbon‐fiber paper. The combination of single‐atom nickel(I) sites and self‐standing array structure gives rise to an excellent electrocatalytic CO2 reduction performance. The introduction of copper tunes the d‐band electron configuration and enhances the adsorption of hydrogen, which impedes the hydrogen evolution reaction. The single‐nickel‐atom electrode exhibits a specific current density of −32.87 mA cm−2 and turnover frequency of 1962 h−1 at a mild overpotential of 620 mV for CO formation with 97 % Faradic efficiency. [ABSTRACT FROM AUTHOR]

Developing superior electrocatalysts for formic acid oxidation (FAO) is the most crucial step in commercializing direct formic acid fuel cells. Herein, we electrodeposited palladium membranes with periodically ordered mesoporosity obtained by asymmetrically replicating the bicontinuous cubic phase structure of a lyotropic liquid‐crystal template. The Pd membrane with the largest periodicity and highest degree of order delivered up to 90.5 m2 g−1 of electrochemical active surface area and 3.34 A mg−1 electrocatalysis capability towards FAO, 3.8 and 7.8 times the values of the commercial Pd/C catalyst, respectively. By controlling the temperature and potential of the electrodeposition procedure, the periodicity area and order degree of the mesoporosity are highly tunable. These Pd membranes gave prototype formic acid fueled cells with 4.3 and 2.4 times the maximum current and power density of the commercial Pd/C catalyst. [ABSTRACT FROM AUTHOR]

Designing effective electrocatalysts for the carbon dioxide reduction reaction (CO2RR) is an appealing approach to tackling the challenges posed by rising CO2 levels and realizing a closed carbon cycle. However, fundamental understanding of the complicated CO2RR mechanism in CO2 electrocatalysis is still lacking because model systems are limited. We have designed a model nickel single‐atom catalyst (Ni SAC) with a uniform structure and well‐defined Ni‐N4 moiety on a conductive carbon support with which to explore the electrochemical CO2RR. Operando X‐ray absorption near‐edge structure spectroscopy, Raman spectroscopy, and near‐ambient X‐ray photoelectron spectroscopy, revealed that Ni+ in the Ni SAC was highly active for CO2 activation, and functioned as an authentic catalytically active site for the CO2RR. Furthermore, through combination with a kinetics study, the rate‐determining step of the CO2RR was determined to be *CO2−+H+→*COOH. This study tackles the four challenges faced by the CO2RR; namely, activity, selectivity, stability, and dynamics. [ABSTRACT FROM AUTHOR]