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

Abstract The electroreduction of CO 2 into the highly value‐added fuel formic acid (HCOOH) has been considered an ideal approach to convert renewable energy and mitigate environmental crisis. SnO 2 electrode is one of the promising candidates to electrocatalytically convert CO 2 to HCOOH, but its poor stability limits its future development and application. In this study, highly stable SnO 2 /Bi 2 O 3 oxide catalysts are obtained by distributing SnO 2 nanoparticles on the surface of Bi 2 O 3 sheets. The XPS spectra revealed an interfacial electronic transportation from Bi 2 O 3 sheets to SnO 2 nanoparticles, which made SnO 2 rich of electrons. The strong interfacial interaction protected the active sites of SnO 2 from self‐reduction in CO 2 electroreduction reaction (CO 2 RR), stabilizing SnO 2 species in the composite catalyst even after long‐term usage. Calculations based on density functional theory signified that the presence of Bi 2 O 3 favored the adsorption of HCOO* intermediate, improved the CO 2 conversion into HCOOH on SnO 2 /Bi 2 O 3 interface. As a result, the SnO 2 /Bi 2 O 3 catalyst attained high performance on CO 2 RR (the highest FE value of 90 % at −1.0 V vs. RHE), suppressing H 2 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).