Effective Formation of Oxygen Vacancies in Black TiO2 Nanostructures with Efficient Solar-Driven Water Splitting

Black TiO2 nanomaterials have attracted considerable attention since they usually exhibit excellent photocatalytic activities. Herein, we report the facile preparation of black TiO2 nanostructures with ultrathin hollow sphere morphology, high crystalline quality, small grain size (similar to 8 nm), and ultrahigh surface area (168.8 m(2) g(-1)) through Al reduction. Electron paramagnetic resonance (EPR) spectra demonstrate the existence of oxygen vacancies in black TiO2 nanostructures, which could increase the donor density and effectively promote the separation and transportation of photogenerated electron-hole pairs. The black TiO2 nanostructures exhibit a high solar-driven hydrogen generation rate (56.7 mmol h(-1) g(-1)) under the full spectrum of solar light, which is nearly 2.5 times than that of pristine TiO2 nanostructures and superior to those kinds of black TiO2 photocatalytic materials reported previously.