TiO2表面沉积Ag粒子及其可见光下降解含盐废水中的苯酚

为了制备可见光激发下能高效降解含盐废水中有机物的光催化剂,首次以商用TiO_2光催化剂(P25)为载体,利用吸附相反应技术一步获得了Ag沉积的可见光响应复合光催化剂.同时,通过XPS、TEM、HRTEM及紫外可见漫反射光谱图,结合多种高含盐水体系中苯酚的光催化降解过程,研究了不同Ag沉积对催化剂可见光活性的影响.结果发现,吸附平衡后P25表面富含水的吸附层可作为反应和粒子的生成场所,生成量子尺寸的Ag粒子.另外,在吸附层中生成的Ag粒子均匀分布于P25表面并与之紧密结合,并在TiO_2晶格结构中引入晶格交错结构.Ag与TiO_2的表面等离子体共振效应和晶格交错结构共同提升了催化剂的可见光响应和电荷的分离效率,增强了催化剂对苯酚的可见光催化性能.在含盐废水体系中,盐离子数量越多,催化剂在可见光下降解苯酚过程受到的干扰越大.

Deposition of Ag particles on TiO2 surface and its photodegradation for phenol in salty wastewater under visible light excitation

To prepare a photocatalyst with efficient performance for degrading organics in salty waste water excited by visible light, commercial TiO₂ photocatalyst (P25) was first used as a carrier, and the visible light-responsive photocatalysts deposited by Ag were obtained by one step using adsorbed-layer nanoreactor synthesis (ANS). Via XPS, TEM, HRTEM and UV-Vis diffuse reflectance spectra, both the effect of Ag deposition on the catalyst microstructure and the enhancement on visible light response of the catalysts were explored. Photodegradation for phenol in several kinds of wastewater with high salt concentration under irradiation of visible light was employed to evaluate the performance of these catalysts. Results showed that a water-rich adsorption layer with several nanometers thick would form on the P25 surface, due to its hydrophilic surface. With the formation of the adsorbed layer, NaOH were also enriched on P25 surface, which made the adsorption layer could be used as a nanoreactor and a site for generating well-distributed and quantum-sized Ag particles (size <10 nm). Moreover, the deposited Ag particles would tightly interact with P25 surface, thus introducing a staggered lattice interlacing structure in the TiO₂ lattice structure. The lattice interlacing structure of TiO₂ and the surface plasmon resonance effect by combination between TiO₂ and quantum-size Ag both improved the visible light response and the charge separation efficiency of the catalysts. Therefore, the photodegradation performance for phenol under visible light excitation were enhanced. In salty waste water, the more salt ions, the stronger interference on the photodegradation for phenol by catalysts under irradiation of visible light.