Influence of photoinduced Si-related self-doping on the photocatalytic activity of SiOBr nanosheets

Under UV irradiation, self-doped Bi5+ is evidenced to be generated on the surface of BiOBr nanosheets, but with well-preserved crystal structure and morphology compared with pure counterpart. Bi5+ self-doping BiOBr (BiOBr-4) exhibits distinct photocatalytic mode for dyes degradation, as compared with pure BiOBr nanosheets. These photodegradation distinctions are mainly due to the simultaneous occurrence of two photoinduced hole (h(+)) mediated oxidation processes on the BiOBr surfaces: (1) a portion of photoexcited h(+) participates in the photocatalytic oxidation of dyes, and (2) partial h(+) involves the oxidation of Bi3+ to Bi5+. Notably, BiOBr-4 nanosheets comparatively show superior photocatalytic activity for the phenol decomposition as well as the bacterial inactivation. Besides Bi5+ induced narrowed bandgap and enhanced light adsorption capacity, significantly, the oxidative Bi5+ acts as electron traps to promote the photoexcited electron-hole separation and accelerate h(+) migration, resulting in the considerable photocatalytic enhancement of BiOBr-4 nanosheets. These novel findings will not only give new insights into the photocatalytic mechanism but also explore new route to enhance photocatalytic performance of Bi-based materials. (C) 2016 Elsevier B.V. All rights reserved.