Copper-triggered delocalization of bismuth p-orbital favours high-throughput CO2 electroreduction

At present, formic acid with the high energy value is the promising product generated by the large-scale renewable electricity-driven CO2 conversion, yet challenges remain in the high-throughput and low-energy production accompanied by the considerable selectivity. Herein, in view of the contribution of electronic modulation to electrocatalytic CO2 reduction reaction (CO2RR) activity of catalysts, the thin BiCu-bimetallic film was designed and built on Cu foam (BiCu/CF) by coupling a facile hydrothermal reaction and an immediate electrochemical transformation. The theoretical evidences demonstrate that Bi p-orbital delocalization triggered by the close-contact metal Cu optimizes reaction pathway of CO2RR, and also favours the orbital hybridization between Bi atom and *OCHO intermediate to form more anti-bonding orbitals, resulting in stabilizing *OCHO intermediate and lowering the thermodynamic barrier of CO2RR. Meanwhile, the electron transferred from catalyst-sites to reaction species also accelerates during CO2RR. Integrating the improved intrinsic activity of Bi catalytic-sites and the superiority of Cu foam in exposing more active sites and the mechanical strength, the BiCu/CF electrode with optimal thickness can acquire satisfactory indicators for industrial application, yielding a record formate current density of 856 mA cm−2, higher than 85% Faradic efficiency, along with a remarkable stability, which outperforms state-of-the-art Bi-based catalysts. This study offers potential avenues of engineering orbital delocalization to rationally construct advanced CO2RR electrodes for the carbon-neutral cycle and utilization.