One step synthesis of N-doped and Au-loaded TiO2 nanoparticles by laser pyrolysis: Application in photocatalysis

Photocatalysis is a major tool for air and water depollution and photocatalysts with improved efficiency in the visible range are still needed. In this context, we show that N-TiO2 nanoparticles modified with Au, called Au/N-TiO2, seem to represent a good compromise: significant photocatalytic activity is observed under visible light together with an activity higher than TiO2 P25 under UV irradiation. In order to demonstrate such efficiency of the Au/N-TiO2 sample, TiO2, Au-TiO2, N-TiO2 and Au modified N-TiO2 nanoparticles were synthesized in one step using the laser pyrolysis method. The photocatalytic activity of the powders was evaluated through the photocatalytic degradation of formic acid (FA) both under UV and visible light irradiation. Under UV irradiation, all the laser-synthesized samples exhibit a high efficiency compared to commercial TiO2 P25. Moreover, the modification by Au induces an enhancement of the photocatalytic activity compared to pure TiO2 even at very low concentrations. Under visible light, the N-doped samples exhibit some photoactivity and the degradation rate of FA in presence of Au/N-TiO2 is much increased compared to N-TiO2. In conclusion, our Au/N-TiO2 sample exhibits efficiency better than P25 under UV together with an activity under visible light