Ultrathin, 2D PdAg alloy mesoporous nanosheets enriched with nanogaps promote electrocatalytic CO2 reduction to formate

Pd-based catalysts have emerged as one unique class of the promising catalysts capable of selectively producing formate near the equilibrium potential during CO2 electroreduction, but still suffering from CO-poisoning at high overpotentials. Achieving an excellent overall performance, including a high formate selectivity, a wide potential window, and a high anti-CO-poisoning ability, remains a significant challenge. Herein, we report the surfactant-templated synthesis of ultrathin, two-dimensional (2D) binary PdAg alloy mesoporous nanosheets enriched with nanogaps among interlinked branches with regulated atomic stoichiometry for highly efficient CO2 reduction to formate. These advanced structural features enable the catalysts to expose abundant active sites, whereas a proper Ag concentration within alloy effectively tailors the electronic structure of Pd through the electron transfer from Ag to Pd. The synergy effect resulting from the structural and electronic perspectives contributes to greatly promoting electrocatalytic CO2 reduction to formate. As a result, the optimized Pd4Ag1 nanosheets display a maximal formate faradic efficiency of 99.4% at −0.1 V versus reversible hydrogen electrode and exhibit a wide potential window of 400 mV for high formate selectivity (>90 %) toward CO2 reduction. Moreover, the detailed electrochemical analyses collectively evidence that Pd4Ag1 nanosheets exhibit attenuated CO binding and CO poisoning. This work highlights a feasible avenue for elaborate designing and constructing efficient formate-targeted catalysts.