Methanol adsorption on an oxidized and a reduced SnO2 thin film

The effects of surface structures of SnO2 thin films on the selective dissociation of methanol have been investigated with X-ray photoelectron spectroscopy. A pre-oxidized surface of SnO2 was in favor of the abstraction of hydrogen from methanol while a highly defective surface of SnO2 prepared by Ar-ion etching favored the dissociation of the CO bond in methanol. The surface, therefore, of pre-oxidized SnO2 reacted as Brønstead base sites but the surface of highly defective SnO2 reacted as Brønstead acid sites. These results clearly show the importance of surface structures in the selection of the acid/base interaction of methanol on the SnO2 surface.