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The relationship between oxygen vacancy (OV) concentration of semiconductors and their photocatalytic performances is far from clarified. In this study, by tuning the OV concentration of BiOCl (001) surface via a novel H 2 O 2 treatment coupled infrared irradiation method, we demonstrate that OV concentration of BiOCl (001) surface strongly determine its surface atomic and electronic structures to modulate the photocatalytic pathways. Being of shorter Bi Bi and Bi O bond lengths as well as more electrons being less localized, BiOCl (001) surface with higher OV concentration favored molecular oxygen activation to generate O 2 2− via a two-electron transfer pathway, while the generated O 2 2− could prevent the over oxidation of amines and thus achieve high selectivity in the oxidation of amines to imines. Similar phenomena were also observed for other semiconductor photocatalysts such as TiO 2 and Nb 2 O 5 , suggesting the generality of oxygen vacancy concentration mediated selectivity enhancement. These findings shed light on the relationship between the oxygen vacancy concentration and the surface structure of semiconductor photocatalysts and offer a novel pathway to realize photocatalytic selective oxidation of amines to imines. [ABSTRACT FROM AUTHOR]

Abstract: SiO2 is generally regarded as an “inert” support of gold catalysts for CO oxidation. We find that silica obtained from a natural clay mineral can be used as excellent gold-support for efficient CO oxidation at relatively low temperature. Fine Au particles are found to locate around the Al sites, rather than on pure SiO2 area. Accordingly, high Au loading and catalytic activity for the clay-based SiO2 supports are ascribed to the residual aluminum originally from the clay. [Copyright &y& Elsevier]