Improving the thermal stability and photocatalytic activity of nanosized titanium dioxide via La3+ and N co-doping

The microstructure and properties of nitrogen and lanthanum co-doped nanocrystalline titania photocatalysts have been studied. The catalyst samples were prepared in a homogeneous precipitation-hydrothermal process and characterized by XRD, XPS, UV-DRS and BET analyses. The results indicated that the nitrogen and La3+ doping could inhibit the phase transformation and crystallite growth of TiO2 and enhance the thermal stability of TiO2 structure. In addition, the experiment results showed that the thermal stability of TiO2 increased with the increasing of La3+. doping. The photocatalytic activities of samples for photodegradation of rhodamine B under visible light irradiation using different La3+ doping contents were also studied. There were optimal values of La3+ doping content for the La3+ doped and nitrogen/La3+ co-doped TiO2 corresponding the highest photodegradation percentages. The nitrogen and La3+ co-doped titania could greatly improve the photocatalytic activity in visible light irradiation, whose probable mechanism is a synergistic effect of co-doping. The nitrogen doping could narrow the band gap of titania and enhance the utilization efficiency of visible light, while the La3+ doping could accelerate the separation of photo-generated electrons and holes. Furthermore, the La3+ doping could increase the adsorption of organic pollutants on the surface of photocatalyst. (c) 2010 Elsevier B.V. All rights reserved.