Solid Bi2O3-derived nanostructured metallic bismuth with high formate selectivity for the electrocatalytic reduction of CO2

CO2electrochemical reduction(CO2ER) is an important research area for carbon neutralization. However, available catalysts for CO2reduction are still characterized by limited stability and activity. Recently, metallic bismuth(Bi) has emerged as a promising catalyst for CO2ER. Herein, we report the solid cathode electroreduction of commercial micronized Bi2O3as a straightforward approach for the preparation of nanostructured Bi. At-1.1 V versus reversible hydrogen electrode in a KHCO3aqueous electrolyte, the resulting nanostructure Bi delivers a formate current density of ～40 mA·cm-2with a current efficiency of ～86%, and the formate selectivity reaches97.6% at-0.78 V. Using nanosized Bi2O3as the precursor can further reduce the primary particle sizes of the resulting Bi, leading to a significantly increased formate selectivity at relatively low overpotentials. The high catalytic activity of nanostructured Bi is attributable to the ultrafine and interconnected Bi nanoparticles in the nanoporous structure, which exposes abundant active sites for CO2electrocatalytic reduction.