Construction of Zinc-Bismuth Composite Oxide Interface Helps Electrochemical Reduction of CO2 to Produce Formic Acid Efficiently and Stably

Abstract

Electro-reduction of CO₂ (CO₂RR) to formic acid is one of the most efficient and promising technologies for the utilization of CO₂, however, designing catalysts with high reactivity and selectivity to achieve the conversion of CO₂ to formic acid is still a great challenge. Therefore, in this study, Bi₂O₃-ZnO/ZnAl₂O₄ composite oxide catalysts were constructed using layered double hydroxides as precursors to enhance the interfacial stability and utilize the synergistic effect of zinc-bismuth dual active sites for the efficient electrocatalytic reduction of CO₂ to formate. The product formate bias current density reached up to 25.8 mA·cm^− 2 at -1.3 V (vs. RHE) in an H-type electrolytic cell and the Faraday efficiency of formate was maintained at about 93% under stability tests up to 14 h, which was superior to most other reported catalysts. In the formation of the Bi₂O₃-ZnO/ZnAl₂O₄ interface, zinc promotes the electroreduction of CO₂ to produce *CO₂⁻ intermediates, while bismuth reduces CO production and improves formic acid selectivity by providing more reactive sites. In addition, the interface between zinc and bismuth optimizes electron and proton flow, helping to maintain a lower energy threshold during the reaction and thus improving catalytic efficiency. This interface engineering approach utilizes zinc-bismuth dual active sites to achieve high selectivity and stability of CO₂ electrocatalytic reduction, providing insights for the development of large-scale efficient CO₂RR catalysts in the future.

Graphical Abstract