Y doping induced stability of Bi2O3 for efficient electrocatalytic reduction of CO2 to formate

Bismuth oxide, a promising electrocatalyst for the formate production via electrocatalytic carbon dioxide reduction reaction (eCO 2 RR), suffers from structural instability at high overpotentials due to reduction-induced deactivation. This study proposes an innovative yttrium (Y) doping strategy that stabilizes Bi 2 O 3 through Y-Bi orbital interactions, effectively suppressing cathodic reduction during eCO 2 RR. Remarkably, the optimized 3 % Y-doped Bi 2 O 3 catalyst delivers outstanding performance, achieving a record formate Faraday efficiency (FE) of 97.9 % at −1.05 V vs. reversible hydrogen electrode (RHE) and maintaining FE > 90 % over a 350 mV potential window. Notably, it sustains FE exceeding 90 % even at industrial-grade current densities up to −160 mA cm −2 in flow cell configuration. Through systematic in situ spectroscopic characterization, density functional theory (DFT) calculations, and electrochemical analysis, we reveal that Y doping modulates the Bi−O electronegativity difference, which simultaneously stabilizes the Bi 3+ oxidation state and enhances adsorption of the critical *OCHO intermediate. This dual-function mechanism establishes a new paradigm for designing stable metal oxide electrocatalysts toward efficient formate electrosynthesis.