Atomically Dispersed Pd Promotes Water Activation and Electrochemical CO2 Reduction to Formate on Bismuth Catalysts.

Abstract

Electrocatalytic CO2 reduction reaction (CO2RR) offers a sustainable route for converting CO2 into value-added chemicals, but its efficiency is limited by sluggish kinetics and poor selectivity. Herein, we report the controlled synthesis of atomically dispersed Pd-modified Bi nanosheets (Pd2.5%-Bi NSs) via a solvent-guided solvothermal method followed by in situ electroreduction. Solvent engineering regulates the morphology of Bi2O3 precursors, resulting in Bi NSs with a high electrochemically active surface area. The incorporation of Pd optimizes the electronic structure, enhances the adsorption of the *OCHO intermediate, and lowers the energy barrier for CO2RR. Notably, atomically dispersed Pd sites facilitate H2O dissociation to provide sufficient active hydrogen, thereby accelerating the protonation kinetics in CO2RR. As a result, Pd2.5%-Bi NSs deliver a current density of 287 mA cm-2 at -1.0 V versus the reversible hydrogen electrode, while maintaining a high formate Faradaic efficiency (FEformate, >91.0%) over a wide current density range of 50-300 mA cm-2, with a maximum FEformate of 95.7% at 200 mA cm-2 in an alkaline flow cell. These results highlight the synergistic effects of moderate morphological control and atomic-level Pd incorporation, providing insights for the rational design of efficient CO2RR catalysts toward selective formate production.