Nitrogen-doped simple and complex oxides for photocatalysis: A review

Semiconductor-based photocatalysis plays a vital role in counteracting worldwide environmental pollution and energy shortage. How to design a visible-light-active photocatalyst is critical for efficient solar energy utilization. Many oxides including TiO₂ are only photoactive in ultraviolet light and doping is an important strategy to extend the photoactive zone. Anion doping is superior to cation doping, which generates more harmful electron-hole recombination centers. Nitrogen doping is more effective than carbon/sulfur doping to achieve high visible-light response. Since 2001, nitrogen-doped TiO₂ photocatalysts have attracted increasing attention due to their strong oxidizing power and considerable visible light response. Considering the fixed atomic environment in simple oxides, complex oxides are more attractive as photocatalysts because of their more flexible physical and chemical properties. To date, no review focuses on the designation strategies for nitrogen-doped simple/complex oxides with high visible-light photoactivity. In this review, the recent progress involving nitrogen-doped simple/complex oxides for photocatalysis is comprehensively summarized. Emphasis is placed on the factors that determine photocatalytic activity and related strategies for the design of active nitrogen-doped oxides. The future challenges are also discussed. This review aims to provide a summary of recent progress in nitrogen-doped oxides for photocatalysis and some useful guidelines for the future development.