Bi-Sn oxides for highly selective CO2 electroreduction to formate in a wide potential window.

The electroreduction of CO 2 into highly value-added fuel, HCOOH, has been considered as a perfect approach to converse 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. Here in this work, highly stable SnO 2 /Bi 2 O 3 oxide catalysts were 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-time working. Calculations based on density functional theory signified that the existence of Bi 2 O 3 favored the adsorption of HCOO* intermediate, improved the CO 2 conversion to HCOOH on SnO 2 /Bi 2 O 3 interface. As a result, the SnO 2 /Bi 2 O 3 catalyst achieved high performance on CO 2 RR (the highest FE C1 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).