Facile preparation of N-doped TiO2 at ambient temperature and pressure under UV light with 4-nitrophenol as the nitrogen source and its photocatalytic activities

Abstract

To date syntheses of nitrogen-doped TiO₂ photocatalysts (TiO_2−xN_x) have been carried out under high temperatures and high pressures with either NH₃ or urea as the nitrogen sources. This article reports for the first time the facile preparation of N-doped TiO₂ (P25 titania) in aqueous media at ambient temperature and pressure under inert conditions (Ar- and N₂-purged dispersions) with 4-nitrophenol (or 4-nitrobenzaldehyde) as the nitrogen source. The resulting N-doped P25 TiO₂ materials were characterized by UV/Vis and X-ray photoelectron spectroscopies (XPS) that confirmed the presence of nitrogen within the photocatalyst; X-ray diffraction (XRD) techniques confirmed the crystalline phases of the doped material. The photocatalytic activity of N-doped TiO₂ was assessed through examining the photodegradation of 4-chlorophenol in aqueous media and iso-propanol as a volatile pollutant under UV/Vis and visible-light irradiation. Under visible light irradiation, undoped P25 was inactive contrary to N-doped P25 that successfully degraded 95% of the 4-chlorophenol (after 10 h) and 23% of iso-propanol (after 2.5 h).