Coupling effect for TiO2/SnO2 compound semiconductor photocatalyst

The photocatalyst of TiO2/SnO2 compound semiconductor was prepared by improved sol-gel method. The coupling mechanism and the factors affecting photocatalytic efficiency were studied by using XRD, gas chromatography, granularity equipment and surface photovoltage spectroscopy. TiO2/SnO2 catalysts were employed for photocatalytic degradation of formaldehyde, The experimental results showed that phtocatalytic efficiency of TiO2 catalyst was greatly enhanced by adding SnO2 into TiO2, and the optimum content of SnO2 was about 20 % (mol), According to the particle close packing rule and experimental result, the strong and weak coupling effect models for TiO2/SnO2 compound semiconductor were proposed. The coupling effect was derived from the close packing structure of the photocatalyst particles. The critical bourn between enhanced and weaken effect depends on whether the close packing structure is three-dimensional or not. The photocatalyst doped with SnO2 less than 20 % (mol) presented a three-dimensional structure, which improved the activity of the photocatalyst due to effective separation of the photogenerated carriers, The opposite situation was occurred when content of SnO2 was more than 20 % (mol).