TiO_2基复合光催化剂研究进展

Research progress of TiO_2-based composite photocatalysts

TiO_2具有化学性质稳定,无毒,价格低廉,易回收等特点被广泛应用于光催化领域。然而由于其带隙较宽,只对紫外光响应,且产生的光生电子-空穴对易复合,导致光催化活性低。研究表明,通过与TiO_2复合形成复合光催化剂能显著改善上述问题。介绍了与TiO_2复合的几种常用方法的基本原理和研究进展。半导体复合方法可以形成内建电场,在内建电场作用下实现光生电荷的有效分离。贵金属沉积方法则利用贵金属上富集电子的特点,分离电子-空穴对,延长光生电荷的寿命,纳米金属的表面等离子体共振效应则可以拓宽催化剂对光的响应范围。通过与碳材料或有机染料复合则可以提高TiO_2对可见光的吸收率,扩大光响应范围,同时能加快光生电荷的转移,减少其复合。最后简要分析了几种方法中存在的问题和未来发展方向。

TiO2 is widely used in the field of photocatalysis due to the stable chemical properties,non-toxic,low price,easy to recovery and so on.However,TiO2 possesses wide band gap and only responses to the ultraviolet light.On the other hand,the photogenerated charges are easy to recombined,which results in low photocatalytic activity.The recent researches show that the above problems can be solved to a great extent by compositing TiO2 with materials such as semiconductors,noble metals,carbon and dyes.The hybridized TiO2 with semiconductor can form the internal electric field,so as to efficiently separate the photogenerated charges.The noble metal deposited on the surface of TiO2 can enrich the photo-induced electrons and separate them.In particular,the surface plasmon resonance effect of nano-metal can enhance the light-response range of the catalysts.The composites of TiO2 with carbon materials or dyes can improve the light absorption and extend to the visiblelight range.Besides,it can accelerate the transfer of charges and suppress the recombination of photo-induced charges.Finally,the problems and future developments of the TiO2 based composites are briefly analyzed and elaborated.