A novel approach for the synthesis of visible-light-active nanocrystalline N-doped TiO2 photocatalytic hydrosol

•A novel route was developed to prepare N doped TiO2 photocatalytic hydrosol.•The route includes precipitation–peptization and hydrothermal crystallization.•The visible-light-active hydrosol is surfactant-free and stable at room temperature.•It exhibits good visible light photocatalytic activity and reusable performance.

A visible-light-active nitrogen doped nanocrystalline titanium dioxide (N–TiO2) hydrosol was prepared by precipitation–peptization method and following with hydrothermal crystallization at 110 °C holding for 6 h. XPS results show that nitrogen ions have been doped into the TiO2 lattice successfully and the UV–Vis absorption spectra indicate that the light absorption edge of the N-doped TiO2 has been red-shifted into visible light region. The photocatalytic performance of the N-doped TiO2 thin film prepared from the synthesized hydrosol was evaluated by photodegrading the gaseous formaldehyde (HCHO) under visible light irradiation. The photodegradation ratio of HCHO reached up to 90% within 24 h and the degradation ratio was stable for ten degradation cycles, indicating the prepared hydrosol has good reusable performance in photodegrading gaseous pollutants.

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