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

Abstract

Pd-based catalysts have emerged as a unique class of promising catalysts capable of selectively producing formate near the equilibrium potential during CO₂ electroreduction but still suffer from CO poisoning at high overpotentials. Achieving an excellent overall performance, including high formate selectivity, a wide potential window, and 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 enabled the catalysts to expose abundant active sites, and a proper Ag concentration within the alloy effectively tailored the electronic structure of Pd through electron transfer from Ag to Pd. The synergetic effect resulting from the structural and electronic perspectives greatly contributed to the promotion of electrocatalytic CO₂ reduction to formate. As a result, the optimized Pd₄Ag₁ nanosheets displayed a maximum formate faradaic efficiency of 99.4% at −0.1 V versus reversible hydrogen electrode and exhibited a wide potential window of 400 mV for high formate selectivity (>90%) toward CO₂ reduction. Moreover, the detailed electrochemical analyses collectively evidenced that the Pd₄Ag₁ nanosheets exhibited attenuated CO binding and CO poisoning. This work highlights a promising avenue for the elaborate design and construction of efficient formate-targeted catalysts.