Enhanced photocatalytic activity of TiO2-xNx loaded with copper ions under visible light irradiation

Nitrogen-doped TiO2 (TiO2-x,N-x,) photocatalysts loaded with various transition metal ions, including Cu, Pt, Ni, Zn and La, were prepared using a wet impregnation method. Photocatalytic activity of the catalysts under visible light irradiation(lambda > 410 nm) for acetaldehyde oxidation was examined. As a result, it was found that photocatalytic activity over TiO2-xNx (concentration of nitrogen was found to be similar to 0.25 at.%) was markedly enhanced by Cu or Pt loading, while Ni, Zn or La loaded TiO2-xNx showed similar photodegradation rate to the bare TiO2-xNx. Among them, the enhancement effect of Cu ion was found highest. The optimum concentration of Cu was found to be 0.5 wt%, and X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) analyses suggested the presence Of Cu2O or Cu hydroxides on the catalyst surface. In terms of the long-term stability of the catalysts, it was confirmed that more than 2100 mu mol Of CO2 was produced when acetaldehyde was continuously photooxidized over 1100 mu mol of Cu loaded TiO2-xNx under visible light for 100 consecutive days (> 410 nm, 0.9 mW/cm(2), in a 1 L vessel). (c) 2006 Elsevier B.V. All rights reserved.