Bi-Sn Oxides for Highly Selective CO Electroreduction to Formate in a Wide Potential Window.

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