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

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 (Pd_2.5%–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, Pd_2.5%–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 (FE_formate, >91.0%) over a wide current density range of 50–300 mA cm⁻², with a maximum FE_formate 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.