Controllable synthesis of porous TiO2 with a hierarchical nanostructure for efficient photocatalytic hydrogen evolution

摘要

TiO2 has been the most suitable candidate for commercial scale-up photocatalysts to date. However, the practical application of TiO2 has been limited, due to its wide band gap (3.0 eV for rutile and 3.2 eV for anatase) and recombination of photoinduced charges. Herein, we report a simple and effective approach to resolve the limitations by manipulating the structure and size of TiO2 to improve the photocatalytic efficiency. By adjusting the volume ratio of hydrochloric acid (HCl) and ethylene glycol (EG), porous TiO2 hierarchical microspheres with controllable size of nanorods were obtained. The nanorods were several hundreds of nanometers long with different average widths, including 5 (TiO2-5), 10 (TiO2-10) and 15 nm (TiO2-15). The band gap of TiO2-5 was as low as 2.75 eV with a super large BET surface area of 216.607 m(2) g(-1). The rate of photocatalytic hydrogen generation for TiO2-5 was 23.74 mmol g(-1) h(-1) under UV-visible light irradiation of 200 mW cm(-2).