Role of Hydroxyl Radicals and Mechanism of Escherichia coli Inactivation on Ag/AgBr/TiO2 Nanotube Array Electrode under Visible Light Irradiation
Role of Hydroxyl Radicals and Mechanism of Escherichia coli Inactivation on Ag/AgBr/TiO2 Nanotube Array Electrode under Visible Light Irradiation
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DOI：
10.1021/es204079d
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发表时间：
2012-04-03
影响因子：
11.4
通讯作者：
Raston, Colin L.
中科院分区：
文献类型：
--
作者：
Hou, Yang;Li, Xinyong;Raston, Colin L.
采用电化学阳极氧化和原位光辅助沉积两步法制备了具有增强可见光活性的Ag/AgBr/TiO 2三元纳米管阵列电极。通过在可见光照射下（λ>420 nm）对大肠杆菌的灭活来评价复合电极的光电催化活性，其完全灭菌性能远远上级其他参比光催化剂。PL，ESR和自由基捕获的研究表明，羟基自由基参与的光电催化反应的主要活性氧物种。通过环境扫描电镜、透射电镜和红外光谱直接观察了细胞壁和细胞膜的破坏过程，并通过测定被杀细菌的钾离子渗漏量进一步证实了这一点。目前的研究结果指出，由OH中心点，O-2（中心点-），空穴和Br-0的氧化攻击从外部到内部的大肠杆菌，导致细胞死亡的光电催化灭活的主要机制。
A ternary Ag/AgBr/TiO2 nanotube array electrode with enhanced visible-light activity was synthesized by a two-step approach including electrochemical process of anodization and an in situ photoassisted deposition strategy. The dramatically enhanced photoelectrocatalytic activity of the composite electrode was evaluated via the inactivation of Escherichia coli under visible light irradiation (lambda>420 nm), whose performance of complete sterilization was much superior to other reference photocatalysts. PL, ESR, and radicals trapping studies revealed hydroxyl radicals were involved as the main active oxygen species in the photoelectrocatalytic reaction. The process of the damage of the cell wall and the cell membrane was directly observed by ESEM, TEM, and FTIR, as well as further confirmed by determination of potassium ion leakage from the killed bacteria. The present results pointed to oxidative attack from the exterior to the interior of the Escherichia coli by OH center dot, O-2(center dot-), holes and Br-0, causing the cell to die as the primary mechanism of photoelectrocatalytic inactivation.