Anti-oxidative microstructure design of ultra-stable N-TiO2 composite for the gaseous photodegradation reactions

N doped TiO2 has been extensively studied for its enhanced absorption to visible light and improved photocatalytic performance, however, its deactivation resulted from the loss of N caused by the oxidation effect is still a major obstacle in photocatalytic applications. In this work, N-TiO2@aTiO2 (N doped TiO2 with amorphous TiO2 layer on the surface) was prepared with the assistance of carbonaceous microsphere (CMS). Its photocatalytic activity in acetaldehyde degradation under visible light (λ ≥ 420 nm) reached 25% and kept stable after 6 h, while N-TiO2 began to deactivate after 80 min and completely lost its activity in the same conditions. Compared with N-TiO2, almost no decrease in N content was observed in N-TiO2@aTiO2 due to the protective effect of TiO2 amorphous layer. The electron spin-resonance (ESR) spectroscopy was further used to measure the variation tendency of N content with reaction time. The results reveal that TiO2 amorphous layer effectively block the loss of N and prevent the deactivation of catalysts. This work provides a new approach to improve the stability of N-TiO2 photocatalysts.