Effects of doping La and Cu on photoinduced charge properties of TiO2 and its relationships with photocatalytic activity

The pure, 1 mol% only La or only Cu doped TiO2 and La and Cu codoped TiO2 were prepared by a sol-gel process. The effects of doping on photoinduced charge properties of nanosized TiO2 were mainly investigated by means of Surface Photovoltage Spectrum (SPS) and Photoluminescence Spectrum (PL), together with their relationships with photocatalytic activity. The results show that La dopant can inhibit the phase transformation of TiO 2 , meanwhile improve the separation rate of photoinduced charge carriers, and enrich the binding surface states. However, Cu dopant has a reverse effect compared to La dopant. This is responsible for the results that doping La is favorable for the increase in the photocatalytic activity for degrading the RhB solution, while doping Cu is bad to photocatalyitc reaction. In addition, codoping La and Cu cannot exhibit an obvious combination effect.