Nitrogen-Doped Bismuth Nanosheet as an Efficient Electrocatalyst to CO 2 Reduction for Production of Formate.

Electrochemical CO ₂ reduction (CO ₂ RR) to produce high value-added chemicals or fuels is a promising technology to address the greenhouse effect and energy challenges. Formate is a desirable product of CO ₂ RR with great economic value. Here, nitrogen-doped bismuth nanosheets (N-BiNSs) were prepared by a facile one-step method. The N-BiNSs were used as efficient electrocatalysts for CO ₂ RR with selective formate production. The N-BiNSs exhibited a high formate Faradic efficiency (FE _formate) of 95.25% at -0.95 V (vs. RHE) with a stable current density of 33.63 mA cm ^-2 in 0.5 M KHCO ₃ . Moreover, the N-BiNSs for CO ₂ RR yielded a large current density (300 mA cm ^-2 ) for formate production in a flow-cell measurement, achieving the commercial requirement. The FE _formate of 90% can maintain stability for 14 h of electrolysis. Nitrogen doping could induce charge transfer from the N atom to the Bi atom, thus modulating the electronic structure of N-Bi nanosheets. DFT results demonstrated the N-BiNSs reduced the adsorption energy of the *OCHO intermediate and promoted the mass transfer of charges, thereby improving the CO ₂ RR with high FE _formate . This study provides a valuable strategy to enhance the catalytic performance of bismuth-based catalysts for CO ₂ RR by using a nitrogen-doping strategy.