Bi–Sn Oxides for Highly Selective CO2 Electroreduction to Formate in a Wide Potential Window

The electroreduction of CO2 into the highly value‐added fuel formic acid (HCOOH) has been considered an ideal approach to convert renewable energy and mitigate environmental crisis. SnO2 electrode is one of the promising candidates to electrocatalytically convert CO2 to HCOOH, but its poor stability limits its future development and application. In this study, highly stable SnO2/Bi2O3 oxide catalysts are obtained by distributing SnO2 nanoparticles on the surface of Bi2O3 sheets. The XPS spectra revealed an interfacial electronic transportation from Bi2O3 sheets to SnO2 nanoparticles, which made SnO2 rich of electrons. The strong interfacial interaction protected the active sites of SnO2 from self‐reduction in CO2 electroreduction reaction (CO2RR), stabilizing SnO2 species in the composite catalyst even after long‐term usage. Calculations based on density functional theory signified that the presence of Bi2O3 favored the adsorption of HCOO* intermediate, improved the CO2 conversion into HCOOH on SnO2/Bi2O3 interface. As a result, the SnO2/Bi2O3 catalyst attained high performance on CO2RR (the highest FEC1 value of 90 % at −1.0 V vs. RHE), suppressing H2 evolution reaction (HER) at high potentials. In particular, the selectivity of HCOOH remained above 76 % in a wide potential window (from −1.0 to −1.4 V vs. RHE) and a long duration (12 h). Wins in the windows: Highly stable SnO2/Bi2O3 electrocatalysts for carbon dioxide reduction (CO2RR) are prepared by distributing SnO2 nanoparticles on the surface of Bi2O3 sheets. The strong interfacial interaction between SnO2 and Bi2O3 protects SnO2 from self‐reduction in CO2RR. Selectivity to HCOOH remains above 76 % over a wide potential window and a long duration.