Surface-disorder-engineering-induced enhancement in the photocatalytic activity of Bi4Ti3O12 nanosheets

NaBH4 reduction method has been used to create surface disorder on Bi4Ti3O12 nanosheets with the aim of enhancing their photocatalytic activity. The NaBH4-treated Bi4Ti3O12 samples were systemati-cally investigated by XRD, TEM, BET, XPS, UV-vis DRS, EIS and transient photocurrent response. It is disclosed that disordered surface layer associated with oxygen vacancy defects is obviously formed on the surface of Bi4Ti3O12 nanosheets, and simultaneously surface defect states are introduced in the forbidden gap of Bi4Ti3O12. The NaBH4-treated Bi4Ti3O12 samples display enhanced visible-light absorption. The photocatalytic performance of the samples was investigated by the degradation of RhB under irradiation of simulated sunlight, UV light and visible light. It is found that the NaBH4-treated Bi4Ti3O12 samples exhibit a significantly enhanced photocatalytic activity under UV irradi-ation. The sample treated at 0.1 M NaBH4 solution shows the highest UV photocatalytic activity, about 1.9 times higher than that of pristine Bi4Ti3O12. This is ascribed to the fact that the induced sur-face defect states can act as electron acceptors and thus facilitates the separation of photogenerated electron-hole pairs. Moreover, the NaBH4-treated Bi4Ti3O12 samples also display a slightly enhanced photocatalytic performance under visible light irradiation, which is due to the enhanced visible light absorption induced by the surface defect states.