Surface engineering of mesoporous anatase titanium dioxide nanotubes for rapid spatial charge separation on horizontal-vertical dimensions and efficient solar-driven photocatalytic hydrogen evolution.

The low charge separation efficiency and sunlight utilisation of traditional titanium dioxide (TiO2) nanoparticle photocatalysts greatly limit their applications. Herein, one-dimensional (1D) mesoporous anatase TiO2 nanotubes with engineered surface defects are fabricated using a combination of simple solvothermal synthesis and high-temperature surface hydrogenation strategy. The obtained mesoporous anatase TiO2 nanotubes with mesopores in the nanotube walls and a specific surface area of 110 m2 g-1 decrease the bandgap from 3.18 to 2.98 eV, enhancing the photoresponse to the visible-light region of the solar spectrum. The defective mesoporous anatase TiO2 nanotubes exhibited an excellent photocatalytic hydrogen evolution rate of 9.8 mmol h-1 g-1, which is approximately 2.5 times higher than that of the pristine anatase TiO2 nanotubes. This can be ascribed to the engineered surface defects and 1D mesoporous nanotube structure favouring efficient spatial charge separation on the horizontal-vertical dimensions, enabling visible-light absorption and exposing abundant surface active sites. This study provides a facile and feasible strategy for the fabrication of high-performance 1D mesostructured semiconductor oxide photocatalysts for efficient solar energy conversion.