Li F B, Li X Z
Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Kowloon, China.
Chemosphere. 2002 Sep;48(10):1103-11. doi: 10.1016/s0045-6535(02)00201-1.
This study investigates the mechanism of photosensitization and the recombination of excited electron-hole pairs affected by depositing platinum (Pt) on the surface of titanium dioxide (TiO2). A new catalyst of Pt-TiO2 was prepared by a photoreduction process. Being model reactions, the photocatalytic oxidation of methylene blue (MB) and methyl orange (MO) in aqueous solutions using the Pt-TiO2 catalyst was carried out under either UV or visible light irradiation. The experimental results indicate that an optimal content of 0.75%Pt-TiO2 achieves the best photocatalytic performance of MB and MO degradation and that the Pt-TiO2 catalyst can be sensitized by visible light. The interaction of Pt and TiO2 was investigated by means of UV-Vis absorption spectra, photoluminescence emission spectra, and X-ray photoelectron emission spectroscopy. The Pt0, Pt2+ and Pt4+ species existing on the surface of Pt-TiO2, and the Ti3+ species existing in its lattice may form a defect energy level. The Pt impurities, including Pt, Pt(OH)2, and PtO2, and the defect energy level absorb visible light more efficiently in comparison with the pure TiO2 and hinder the recombination rate of excited electron-hole pairs.
本研究探讨了通过在二氧化钛（TiO₂）表面沉积铂（Pt）来影响光致敏机制以及激发电子 - 空穴对复合的情况。通过光还原法制备了一种新型的Pt - TiO₂催化剂。作为模型反应，使用Pt - TiO₂催化剂在紫外光或可见光照射下对水溶液中的亚甲基蓝（MB）和甲基橙（MO）进行光催化氧化。实验结果表明，0.75%的Pt - TiO₂具有最佳含量，实现了对MB和MO降解的最佳光催化性能，并且Pt - TiO₂催化剂可被可见光敏化。通过紫外 - 可见吸收光谱、光致发光发射光谱和X射线光电子发射光谱研究了Pt与TiO₂的相互作用。存在于Pt - TiO₂表面的Pt⁰、Pt²⁺和Pt⁴⁺物种以及存在于其晶格中的Ti³⁺物种可能形成一个缺陷能级。与纯TiO₂相比，包括Pt、Pt(OH)₂和PtO₂在内的Pt杂质以及缺陷能级更有效地吸收可见光，并阻碍激发电子 - 空穴对的复合率。
