Nitrogen-Doped Bismuth Nanosheet as an Efficient Electrocatalyst to CO₂ Reduction for Production of Formate

Electrochemical CO2 reduction (CO2RR) 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 CO2RR 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 CO2RR with selective formate production. The N-BiNSs exhibited a high formate Faradic efficiency (FEformate) of 95.25% at −0.95 V (vs. RHE) with a stable current density of 33.63 mA cm−2 in 0.5 M KHCO3. Moreover, the N-BiNSs for CO2RR yielded a large current density (300 mA cm−2) for formate production in a flow-cell measurement, achieving the commercial requirement. The FEformate 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 CO2RR with high FEformate. This study provides a valuable strategy to enhance the catalytic performance of bismuth-based catalysts for CO2RR by using a nitrogen-doping strategy