Facile and large-scale synthesis of defective black TiO2−x (B) nanosheets for efficient visible-light-driven photocatalytic hydrogen evolution

Abstract

In the work, we firstly report the facile and large-scale synthesis of defective black TiO2−x (B) nanosheets via a dual-zone NaBH4 reduction method. The structure, physico-chemical, and optical properties of TiO2−x (B) nanosheets were systematically characterized by powder X-ray diffraction, Raman spectroscopy, UV-Vis absorption spectroscopy, and X-ray photoelectron spectroscopy, etc. The concentration of Ti3+ can be well tuned by NaBH4 reduction. With increasing the mass ratio of NaBH4 to TiO2 (B), the generation of Ti3+ defects gives rise to the increased intensity of a broad band absorption in the visible wavelength range. It is demonstrated that the TiO2−x (B) photocatalyst synthesized with the mass ratio of NaBH4 to TiO2 (B) of 3:1 exhibited an optimum photocatalytic activity and excellent photostability for hydrogen evolution under visible-light irradiation. By combining the advantages of 2D TiO2 (B) nanosheets architecture with those of Ti3+ self-doping and simultaneous production of oxygen vacancy sites, the enhanced photocatalytic performance of the defective TiO2−x (B) nanosheets was achieved.