Ordered porous copper sulfide with hollow interior for superior electrochemical CO₂ to formate conversion

Targeted for superior formate production from electrochemical carbon dioxide (CO₂) reduction, hollow ordered porous copper sulfide cuboctahedra (HOP CuS-CO) with controlled shell thicknesses were designed and synthesized in this study. Uniform and interconnected pores are evenly distributed in the hollow shells of HOP CuS-CO. Capitalizing on the merits of porous cages, HOP CuS-CO exhibit outstanding formate production with a Faradaic efficiency up to 70.3 % and catalytic stability of 26 h under an applied potential of −1.1 V versus reversible hydrogen electrode (vs. RHE). In situ Raman spectroscopy results reveal that the adsorption of HCOO* intermediates is promoted on the catalyst surfaces of HOP CuS-CO due to a spatial confinement effect, which leads to highly efficient CO₂ to formate conversion. The present study offers insights for designing materials toward superior formate production from electrochemical CO₂ reduction.