Loading effects of silver oxides upon generation of reactive oxygen species in semiconductor photocatalysis
Loading effects of silver oxides upon generation of reactive oxygen species in semiconductor photocatalysis
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DOI：
10.1039/b719913a
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发表时间：
2008-01-01
影响因子：
3.3
通讯作者：
Nakagaki, Ryoichi
中科院分区：
文献类型：
--
作者：
Kohtani, Shigeru;Yoshida, Kazuhiro;Nakagaki, Ryoichi
用鲁米诺化学发光法(CL)和自旋捕集荧光法分别研究了碱性条件下(pH 12.0)载银、载银、载银的TiO2光催化剂和BiVO4光催化剂悬浮液中超氧阴离子自由基(O-2(-中心点))和OH自由基的产生，其中对苯二甲酸与OH反应生成了高荧光的2-羟基对苯二甲酸(TAOH)。在TiO2和BiVO4上负载AgO后，观察到的鲁米诺化学发光强度显著增强。这可能是由于AgO表面的热催化活性的协同效应以及光催化剂/AgO界面的有效电子-空穴分离而促进了负载型光催化剂上O-2(-中心点)的产生。另一方面，虽然二氧化钛样品的TAOH生成速率比BiVO4样品的高出约三个数量级，但AgO对TAOH生成的负载效应并不像CL观测的那样显著。根据鲁米诺化学发光动力学和TiO2光催化剂、BiVO4光催化剂和银氧化物的近似带边位置，讨论了这些光催化剂上产生O-2(-中心点)和OH自由基的性质。
Superoxide anion radical (O-2(-center dot)) and OH radical generations in suspensions of Ag metal-, Ag2O-, or AgO-loaded TiO2 and BiVO4 photocatalysts in alkaline conditions ( pH 12.0) were examined by means of a luminol chemiluminescence ( CL) technique and a spin-trapping fluorescence one in which terephthalic acid reacts with an OH radical to afford the highly fluorescent 2-hydroxyterephthalic acid (TAOH), respectively. The observed luminol CL intensity was remarkably enhanced by the AgO loading on TiO2 as well as BiVO4. This can be explained by enhancement of O-2(-center dot) production on the AgO-loaded photocatalysts caused by the synergetic effects on the thermocatalytic activity upon the AgO surface and the efficient electron-hole separation at the photocatalyst/AgO interface. On the other hand, loading effects of AgO on the TAOH formation were not so significant compared to those on the CL observation, though the TAOH formation rates for the TiO2 samples were much larger than those for the BiVO4 ones by about three orders of magnitude. The properties of O-2(-center dot) and OH radical generations on these photocatalysts are discussed on the basis of the luminol CL kinetics and approximate band edge positions of TiO2, BiVO4, and silver oxides.