Low-Crystallinity-Induced Lattice-Distorted Bismuth Nanosheets for Enhanced Electrocatalytic CO₂ Reduction to Formate

The electrochemical CO₂ reduction reaction (CO₂RR) to formate offers a sustainable route for carbon neutrality, yet achieving high activity and selectivity remains challenging. Herein, we report a crystallinity-mediated reconstruction strategy to engineer lattice compressive Bi nanosheets for efficient CO₂ electroreduction. Ex situ electrochemical reduction of BOC-L with low crystallinity rapidly forms lattice-distorted Bi nanosheets (Bi NS-L), while BOC-H with high crystallinity undergoes slower reconstruction, yielding ordered Bi nanosheets (Bi NS-H). The compressive strain enhances the CO₂ adsorption and improves the intrinsic activity of Bi nanosheets. Consequently, Bi NS-L achieves a formate Faradaic efficiency of 94.8% at -1.08 V vs RHE, surpassing Bi NS-H (89.1%), with a partial current density of 247.49 mA cm^-2 in a flow cell. Moreover, coupling the CO₂RR with anodic glycerol oxidation (GOR) reduces the cell voltage to 2.3 V (2.5 V for the CO₂RR/OER) at 200 mA cm^-2, enabling 3965.6 μmol h^-1 cm^-2 formate production.