N-Rich Doped Anatase TiO 2 with Smart Defect Engineering as Efficient Photocatalysts for Acetaldehyde Degradation.

Nitrogen (N) doping is an effective strategy for improving the solar-driven photocatalytic performance of anatase TiO 2 , but controllable methods for nitrogen-rich doping and associated defect engineering are highly desired. In this work, N-rich doped anatase TiO 2 nanoparticles (4.2 at%) were successfully prepared via high-temperature nitridation based on thermally stable H 3 PO 4 -modified TiO 2 . Subsequently, the associated deep-energy-level defects such as oxygen vacancies and Ti 3+ were successfully healed by smart photo-Fenton oxidation treatment. Under visible-light irradiation, the healed N-doped TiO 2 exhibited a ~2-times higher activity of gas-phase acetaldehyde degradation than the non-treated one and even better than standard P25 TiO 2 under UV-visible-light irradiation. The exceptional performance is attributed to the extended spectral response range from N-rich doping, the enhanced charge separation from hole capturing by N-doped species, and the healed defect levels with the proper thermodynamic ability for facilitating O 2 reduction, depending on the results of ∙O 2 - radicals and defect measurement by electron spin resonance, X-ray photoelectron spectroscopy, atmosphere-controlled surface photovoltage spectra, etc. This work provides an easy and efficient strategy for the preparation of high-performance solar-driven TiO 2 photocatalysts.