一种简单的提高无定形TiO_2光催化活性的方法及其在增透膜中的应用（英文）

Simple Way to Enhance the Photocatalytic Activity and Application in Antireflective Coatings for Amorphous TiO_2

通过简单的溶胶-凝胶法制备得到了小粒径的无定形TiO_2粒子,并将其沉积在多孔SiO_2膜层表面,多孔SiO_2膜层大的表面积有助于无定形TiO_2的良好分散,高度分散的无定形TiO_2粒子对膜层的光学性能影响较小,通过匹配合适的低折射率的SiO_2膜层,制备得到的SiO_2&无定形TiO_2(SiO_2&amorphous-TiO_2)膜层表现出和理想单层增透膜相似的光学性能。同时SiO_2&amorphous-TiO_2的光催化性能显著提高,明显高于单层无定形TiO_2。而且SiO_2&无定形TiO_2膜层甚至表现出比相应的负载锐钛矿型TiO_2的膜层,即SiO_2&锐钛矿TiO_2,更高的光催化活性,这一反常现象的原因是,无定型TiO_2膜层表面丰富的羟基有助于减少空穴-电子对的复合,其相对疏松的结构能够加快光生电子-空穴的转移速率,而这些因素的影响超过了晶型结构对光催化活性的影响。同时SiO_2膜层的孔隙结构在浸渍-提拉镀制过程中,自发形成并不需要后续热处理过程,因此,整个SiO_2&无定形TiO_2膜层的制备均可在室温下完成,能够实现其在不耐热基片上的应用。

Small-sized amorphous TiO2 nanoparticles were prepared and deposited on mesoporous SiO2 support via sol-gel method at room temperature.This structure greatly increases the surface areas of the amorphous TiO2 particles,which facilitates the enhancement of photocatalytic activity and preserved the optical performance of the films in the same time.The resultant SiO2&amorphous-TiO2 films afford glasses a maximum transmittance of 99.97%and show a much higher photocatalytic activity than the monolayer amorphous TiO2 film.Surprisingly,the SiO2&amorphous-TiO2 even shows a higher photocatalytic activity than the counterparts with anatase phase.This higher photocatalytic activity is attributed to abundant surface hydroxyl groups and relative loose structure of the amorphous TiO2 nanoparticles,which can help enhance photocatalytic activity through reducing recombination of electron-hole pairs and increase the migration rates of the photoexcited electrons and holes,respectively.And these characteristics may be preferable to crystal structure for enhancing photocatalytic activity.Meanwhile,the coating process is very simple,low cost and conducted at room temperature,which is feasible for polymer substrates.