Enhancement in Ethanol Electrooxidation by SnOxNanoislands Grown on Pt(111): Effect of Metal Oxide–Metal Interface Sites

An integrated surface science and electrochemistry approach has been used to prepare and characterize SnO x /Pt(111) model catalysts and evaluate their electrochemical activity for the ethanol oxidation reaction (EOR). Nanoislands of SnO x are deposited onto the Pt(111) by reactive layer assisted deposition in which Sn metal is vapor deposited onto a Pt(111) surface precovered by NO 2 . X-ray photoelectron spectroscopy (XPS) shows that the SnO x islands are highly reduced with Sn 2+ being the dominant chemical species. After exposing the SnO x /Pt(111) surface to H 2 O or an electrolyte solution, XPS provides evidence for a significant amount of H 2 O/OH adsorbed on the reduced SnO x surfaces. Electrochemical testing reveals that the catalytic performance of Pt(111) toward ethanol electrooxidation is significantly enhanced with SnO x islands added onto the surface. The enhanced EOR activity is tentatively attributed to the efficient removal of CO ads -like poisoning species at Pt sites by oxygen-containing species that are readily formed on the SnO x nanoislands. Moreover, the strong dependence of the EOR activity on SnO x coverage provides experimental evidence for the importance of SnO x –Pt interface sites in the EOR.