High surface area black TiO2 templated from ordered mesoporous carbon for solar driven hydrogen evolution

Abstract

Hydrogen reduction of TiO2 to generate surface Ti3+ can significantly increase the photochemical activity under solar-light illumination. However, the low surface areas of commercial TiO2 limit their photocatalytic activities. Herein, we report a high surface area ordered mesoporous black TiO2, which exhibits an improved photocatalytic performance. The TiO2 material was prepared by using a highly ordered mesoporous carbon CMK-3 as a hard template, which possesses very high surface area, large pore volume and uniform mesopores. By using the advantage of pore confinement in the mesoporous carbon template, TiO2-carbon composites were annealed at different temperatures to investigate the influence of the crystallinity of TiO2 on the photocatalytic hydrogen production. TiO2 calcined at 500 °C, having a high surface area (up to 158 m2 g−1), large pore volume (up to 0.62 cm3 g−1), uniform pore size (5–6 nm), and anatase crystal structure, indicated the highest hydrogen generation rate. Since the TiO2 has been treated at a higher temperature in the confinement of the mesoporous carbon, the TiO2 can easily be reduced at 500 °C under hydrogen atmosphere to generate surface Ti3+ species without destruction of the mesostructure and exhibits a high solar-driven hydrogen evolution rate (188 μmol h−1), which is more than two times higher than that of commercial TiO2 (82 μmol h−1).