Methanol oxidation over rutile Au1@TiO2 catalyst: Importance of facets and oxygen vacancy

Abstract

Single-atom catalysts have attracted exceptional interest of researchers. However, the arguing whether tuning the interactions between the dispersed single metals and the support can enhance the activity, selectivity and stability of single atom catalysts is still open. Herein, single atom Au catalyst (rutile Au1@TiO2) is presented via density functional theory calculations, which exhibits high efficiency for methanol oxidation to formate, especially the exposed (110) facet. Rutile Au1@TiO2 (110) facet prefers to localize at 6-fold Ti site under rich-oxygen conditions; methanol goes through adsorption, OH dissociation, CH dissociation, O2 molecule adsorption, and withdraws H2O and formate to gas phase separately. In particular, a significant step on the way to methanol oxidation is the oxygen vacancy formation at the reduced rutile Au1@TiO2 (110) surface after CH scission and H2O desorption. The subsequent adsorbed O2 molecule does only provide oxygen species for methanol oxidation, but not fill surface oxygen vacancy, which promotes formate formation and desorption to develop very well.