TiO2/SnO2复合光催化剂的耦合效应

摘要

采用改进的 sol gel技术制备 TiO2/SnO2耦合型半导体光催化剂 ,利用 XRD、气相色谱仪、粒度仪和表面光电压装置等研究了耦合型半导体光催化机理和光催化效率的影响因素 ,并通过降解甲醛探讨其在空气污染治理中的作用 .实验结果表明 ,添加 20 ％ (mol) SnO2的复合半导体光催化剂 ,其光催化效率比纯 TiO2高一倍以上 .据实验结果和粒子紧密堆积原理 ,提出强耦合效应和弱耦合效应的光催化反应模型 ,并用此模型较好地解释了 TiO2/SnO2复合型半导体光催化剂的光催化效率随 SnO2含量变化规律 .%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).