Dynamic reconstructuring of CuS/SnO2-S for promoting CO2 electroreduction to formate

As the “emission peak and carbon neutrality peak” are proceeding all over the world, CO2 electroreduction is studied extensively as it is a powerful way to transform CO2 into value-added products. The earth-abundant Sn-based materials and copper sulfides as electrochemical catalysts have shown activity for generating formate from CO2 electroreduction. Herein, the composite of CuS and S-doped SnO2 (CuS/SnO2-S) was synthesized by a redox reaction under room temperature. The unique structural reconstruction of CuS/SnO2-S nanoparticles to Cu/Sn/Cu6.26Sn5 nanowires decreases the energy barrier of the adsorption of CO2, and increases the adsorption of *H, primarily suppressing the competing reaction of hydrogen evolution reaction (HER). As a result, at − 0.8 V vs. RHE, it reaches an electrochemical CO2-to-formate conversion with a Faradaic efficiency (FE) of 84.9% at a yield of 8860 µmol h−1 cm−2 under a partial current density of ∼18.8 mA cm−2 in an H-type reactor. This study provides significant insight into the structural evolution of the CuSn sulfides and the mechanism of formate formation.