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Antimony (Sb) as a low-toxic and cost-effective metal is a promising material to catalyse CO 2 electroreduction to formate with practical viability. However, monometallic Sb suffers from intrinsically low catalytic activity and the competing hydrogen evolution. Here, we report nanoporous Sb-Bi alloys for substantially improving the catalytic activity of Sb and suppressing hydrogen evolution. The optimal Sb-Bi alloy exhibits a maximum Faradaic efficiency of 95.8 % toward formate production, surpassing the 11.6 % of monometallic Sb counterpart. Operating the catalyst in the flow cell demonstrates a formate partial current density of 734 mA cm−2 and cathodic energy efficiency of 59 % at a moderate overpotential of 800 mV, representing a record formate-production performance so far. Experimental and theoretical studies indicate that the Sb-Bi interactions activate Sb sites to selectively stabilize *OCHO intermediates, facilitating CO 2 -to-formate conversion. This work offers insights in manipulating bimetallic interactions to transform inert materials into active catalysts for efficient electrocatalysis. [Display omitted] • Sb-Bi interactions induce electrocatalytic switching from HER to CO 2 ER. • Sb 2 Bi 6 exhibits a maximum formate selectivity of 95.8 % in an H-type cell. • Sb 2 Bi 6 achieves a record formate activity of 734 mA cm−2 in a flow cell. • Sb-Bi interactions facilitate Sb sites to stabilize *OCHO for formate formation. [ABSTRACT FROM AUTHOR]

A surface reconstructing phenomenon is discovered on a defect‐rich ultrathin Pd nanosheet catalyst for aqueous CO2 electroreduction. The pristine nanosheets with dominant (111) facet sites are transformed into crumpled sheet‐like structures prevalent in electrocatalytically active (100) sites. The reconstruction increases the density of active sites and reduces the CO binding strength on Pd surfaces, remarkably promoting the CO2 reduction to CO. A high CO Faradaic efficiency of 93 % is achieved with a site‐specific activity of 6.6 mA cm−2 at a moderate overpotential of 590 mV on the reconstructed 50 nm Pd nanosheets. Experimental and theoretical studies suggest the CO intermediate as a key factor driving the structural transformation during CO2 reduction. This study highlights the dynamic nature of defective metal nanosheets under reaction conditions and suggests new opportunities in surface engineering of 2D metal nanostructures to tune their electrocatalytic performance. [ABSTRACT FROM AUTHOR]

A surface reconstructing phenomenon is discovered on a defect‐rich ultrathin Pd nanosheet catalyst for aqueous CO2 electroreduction. The pristine nanosheets with dominant (111) facet sites are transformed into crumpled sheet‐like structures prevalent in electrocatalytically active (100) sites. The reconstruction increases the density of active sites and reduces the CO binding strength on Pd surfaces, remarkably promoting the CO2 reduction to CO. A high CO Faradaic efficiency of 93 % is achieved with a site‐specific activity of 6.6 mA cm−2 at a moderate overpotential of 590 mV on the reconstructed 50 nm Pd nanosheets. Experimental and theoretical studies suggest the CO intermediate as a key factor driving the structural transformation during CO2 reduction. This study highlights the dynamic nature of defective metal nanosheets under reaction conditions and suggests new opportunities in surface engineering of 2D metal nanostructures to tune their electrocatalytic performance. [ABSTRACT FROM AUTHOR]

Polynary single‐atom structures can combine the advantages of homogeneous and heterogeneous catalysts while providing synergistic functions based on different molecules and their interfaces. However, the fabrication and identification of such an active‐site prototype remain elusive. Here we report isolated diatomic Ni‐Fe sites anchored on nitrogenated carbon as an efficient electrocatalyst for CO2 reduction. The catalyst exhibits high selectivity with CO Faradaic efficiency above 90 % over a wide potential range from −0.5 to −0.9 V (98 % at −0.7 V), and robust durability, retaining 99 % of its initial selectivity after 30 hours of electrolysis. Density functional theory studies reveal that the neighboring Ni‐Fe centers not only function in synergy to decrease the reaction barrier for the formation of COOH* and desorption of CO, but also undergo distinct structural evolution into a CO‐adsorbed moiety upon CO2 uptake. [ABSTRACT FROM AUTHOR]

Polynary single‐atom structures can combine the advantages of homogeneous and heterogeneous catalysts while providing synergistic functions based on different molecules and their interfaces. However, the fabrication and identification of such an active‐site prototype remain elusive. Here we report isolated diatomic Ni‐Fe sites anchored on nitrogenated carbon as an efficient electrocatalyst for CO2 reduction. The catalyst exhibits high selectivity with CO Faradaic efficiency above 90 % over a wide potential range from −0.5 to −0.9 V (98 % at −0.7 V), and robust durability, retaining 99 % of its initial selectivity after 30 hours of electrolysis. Density functional theory studies reveal that the neighboring Ni‐Fe centers not only function in synergy to decrease the reaction barrier for the formation of COOH* and desorption of CO, but also undergo distinct structural evolution into a CO‐adsorbed moiety upon CO2 uptake. [ABSTRACT FROM AUTHOR]