Methyl Group-Promoted Generation of Oxygen Vacancies in an Aerobically Annealed TiO2 Nanostructure for Photocatalytic H2 Production

Surmounting the extreme synthesis conditions (e.g., hazardous reagents/gas and temperature) of defective nano-TiO2 photocatalysts is central for effective hydrogen production. Here, controllable synthesis of oxygen-deficient TiO2 nanostructures by a simple pre-adsorbed organic C–H group (like CH2 and CH3)-assisted strategy is first proposed. In addition to directly leading to the formation of oxygen vacancies at room temperature in the air, the surface-bound C–H groups also amazingly causes a significant crystallization delay during the annealing process, which finally realizes the creation of abundant oxygen vacancies under benign aerobic-annealing conditions. Concomitant with the generation of adjustable oxygen vacancies, the photocatalytic performance of the resultant TiO2 could be fine-tuned. The optimized oxygen vacancy-containing TiO2 nanomaterial (calcined at 300 °C) shows an extraordinary performance when doped with 1% Pt using triethanolamine as the sacrificial agent, exhibiting an impressive evolution rate of 5.47 mmol h–1 g–1 under visible-light irradiation, being more than five times higher than that of unmodified TiO2 and surpassing most of the previously reported oxygen-deficient TiO2 nanostructures. Experimental characterizations and theoretical calculations show that the exceptional performance could be attributed to oxygen vacancy-induced enhanced visible light absorption, increased electron–hole pairs separation, and reduced H2 absorption energy. This study offers a green method for creating defective TiO2 photocatalysts, making it easier for mass production and vigorously promoting commercialization.