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

Black TiO 2 nanomaterials have attracted considerable attention since they usually exhibit excellent photocatalytic activities. Herein, we report the facile preparation of black TiO 2 nanostructures with ultrathin hollow sphere morphology, high crystalline quality, small grain size (∼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 TiO 2 nanostructures, which could increase the donor density and effectively promote the separation and transportation of photogenerated electron–hole pairs. The black TiO 2 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 TiO 2 nanostructures and superior to those kinds of black TiO 2 photocatalytic materials reported previously.