Synthesis of disorder–order TaON homojunction for photocatalytic hydrogen generation under visible light

Herein, disorder–order TaON homojunction photocatalysts with different concentrations of surface oxygen vacancies were prepared by a simple and novel aluminothermic reduction method. The surface oxygen vacancy defects disrupt the periodicity of the crystal surface and weaken the crystallinity of TaON particles, resulting in a crystalline core and an amorphous shell structure. Introduction of oxygen vacancy plays a pivotal role in regulating the band structure and charge kinetic behaviors of TaON. It renders not only the appearance of defect band level in the forbidden band, which allows drastically broadened and enhanced light absorption of TaON particles, but also the formation of the disorder–order TaON homojunction, which increases the concentration of photogenerated carriers, inhibits the recombination of photogenerated charge and promotes effective surface photocatalytic reaction, thus resulting in significantly improved photocatalytic hydrogen production activity of TaON photocatalyst. The aluminothermic reduction temperature for optimum photocatalytic activity of TaON was 400 °C, giving a hydrogen production activity of 25 μmol g⁻¹ h⁻¹, about twice as pure TaON under visible light. This work could shed light on exploring oxygen vacancy-activated photocatalytic materials with great potential for solar-energy conversion.