Promotion of CO₂ Electroreduction on Bismuth Nanosheets with Cerium Oxide nanoparticles

Formic acid (HCOOH) is a highly energy efficient product of the electrochemical CO₂ reduction reaction (CO₂RR). Bismuth-based catalysts have shown promise in the conversion of CO₂ to formic acid, but there is still a great need for further improvement in selectivity and activity. Herein, we report the preparation of Bi nanosheets decorated by cerium oxide nanoparticles (CeO_x) with high Ce³⁺/Ce⁴⁺ ratio and rich oxygen vacancies. The CeO_x nanoparticles affect the electronic structures of bismuth, enhance CO₂ adsorption, and thus promote the CO₂RR properties of Bi nanosheets. Compared with elemental Bi nanosheets, the hetero-structured CeO_x/Bi nanosheets exhibit much higher activity over a wide potential window, showing a current density of 16.1 mA cm⁻² with a Faradaic efficiency of 91.1% at −0.9 V vs. reversible hydrogen electrode.