Hu Chun, Lan Yongqing, Qu Jiuhui, Hu Xuexiang, Wang Aimin
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, P. R. China.
J Phys Chem B. 2006 Mar 9;110(9):4066-72. doi: 10.1021/jp0564400.
Ag/AgBr/TiO2 was prepared by the deposition-precipitation method and was found to be a novel visible light driven photocatalyst. The catalyst showed high efficiency for the degradation of nonbiodegradable azodyes and the killing of Escherichia coli under visible light irradiation (lambda>420 nm). The catalyst activity was maintained effectively after successive cyclic experiments under UV or visible light irradiation without the destruction of AgBr. On the basis of the characterization of X-ray diffraction, X-ray photoelectron spectroscopy, and Auger electron spectroscopy, the surface Ag species mainly exist as Ag0 in the structure of all samples before and after reaction, and Ag0 species scavenged hVB+ and then trapped eCB- in the process of photocatalytic reaction, inhibiting the decomposition of AgBr. The studies of ESR and H2O2 formation revealed that OH and O2- were formed in visible light irradiated aqueous Ag/AgBr/TiO2 suspension, while there was no reactive oxygen species in the visible light irradiated Ag0/TiO2 system. The results indicate that AgBr is the main photoactive species for the destruction of azodyes and bacteria under visible light. In addition, the bactericidal efficiency and killing mechanism of Ag/AgBr/TiO2 under visible light irradiation are illustrated and discussed.
采用沉积沉淀法制备了Ag/AgBr/TiO₂，发现其为一种新型可见光驱动光催化剂。该催化剂在可见光照射（λ>420 nm）下对难生物降解偶氮染料的降解及大肠杆菌的杀灭表现出高效性。在紫外或可见光照射下连续循环实验后，催化剂活性得到有效保持，且AgBr未被破坏。基于X射线衍射、X射线光电子能谱和俄歇电子能谱表征，反应前后所有样品结构中的表面Ag物种主要以Ag⁰形式存在，且在光催化反应过程中Ag⁰物种捕获hVB⁺后再俘获eCB⁻，抑制了AgBr的分解。电子自旋共振和H₂O₂生成的研究表明，在可见光照射的Ag/AgBr/TiO₂水悬浮液中形成了·OH和O₂⁻，而在可见光照射的Ag⁰/TiO₂体系中没有活性氧物种。结果表明，AgBr是可见光下破坏偶氮染料和细菌的主要光活性物种。此外，还对可见光照射下Ag/AgBr/TiO₂的杀菌效率和杀灭机制进行了说明和讨论。
