Crystalline/amorphous Bi-BiNiO x electrocatalyst enables efficient concurrent formate production from CO 2 and methanol

Electrochemical CO2 reduction reaction (CO2RR) to formate presents a technoeconomic route for CO2 utilization under mild conditions, yet practical implementation is constrained by the high energy consumption (>90% of total input) of the anodic oxygen evolution reaction (OER). Replacement of OER by partial methanol oxidation reaction (MOR) could lead to simultaneous formate production at both electrodes and remarkably reduce the overall energy consumption. Herein, we designed a two-electrode system featuring a nickel foam-supported crystalline/amorphous bismuth-bismuth nickel oxide composite cathode (Bi-BiNiOx/NF) and a β-Ni(OH)₂ anode, achieving excellent formate production behavior. The crystalline/amorphous Bi-BiNiOx/NF cathode delivers exceptional CO2RR performance, achieving 98.9% formate Faradaic efficiency (FEformate) at -0.90 V vs. RHE and maintaining >90.7% FEformate over 72 h continuous operation—attributed to its Bi-Ni bimetallic synergy and crystalline/amorphous heterostructure that enhance active site exposure and reaction kinetics. The integrated CO2RR||MOR system operates stably for 90 h at 2.2 V and 10 mA cm-2, sustaining >90% FEformate at both electrodes with a cell voltage (1.760 V) significantly lower than conventional CO2RR||OER systems (1.953 V). This work demonstrates efficient concurrent formate electrosynthesis and establishes an energy-efficient paradigm for electrocatalytic CO2 valorization through synergistic catalyst design and reaction pathway integration.