在水溶液中使用O2和H2O标记的O2和H2O标记的氧-18来确定TiO2-光触媒的环开放机制
Xibin Pang1, Wei Chang, Chuncheng Chen
1Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, The Chinese Academy of Sciences , Beijing 100190, China.
Journal of the American Chemical Society
|May 23, 2014
概括
分子氧 (O2) 在TiO2光催化中直接分裂芳香C-C键,插入单个氧原子. 这一发现澄清了芳香污染物的降解机制.
科学领域:
- 环境化学环境化学
- 光催化作用的光催化
- 有机化学 有机化学
背景情况:
- 芳香C-C键裂变对于通过TiO2光催化分解芳香污染物至关重要.
- 由于复杂的中间体和有限的反应模型,O2和H2O在这个过程中的确切作用仍然不清楚.
研究的目的:
- 阐明分子氧 (O2) 和水 (H2O) 在芳香型 sp-C 键的 TiO2 光催化裂变中的精确作用.
- 确定参与芳香环开放的初级中间产物和反应机制.
主要方法:
- 使用氧-18同位素标签对O2和H2O进行标记.
- 研究了3,5-di-tert-butylcatechol (DTBC) 的光催化降解,使用TiO2在水溶中.
- 分析了初级中间产品的结构,特别是七分环无水化物.
主要成果:
- 提供了直接证据,证明从O2中插入单个氧原子到芳香C-C键中,确定O2是直接的环开放剂.
- 证明了环开放机制涉及单个O原子的结合,而不是之前建议的O2.2的1,2-添加.
- 观察到,内醇与外醇产品的比率受到TiO2催化剂的颗粒大小的影响,这表明O2激活和表面协调部位之间的相关性.
结论:
- 分子氧 (O2) 是TiO2光催化中的芳香环分裂的决定性代理物.
- 该机制涉及从O2中加入单个O原子,澄清了之前的假设.
- TiO2催化剂的特性,如粒子大小和表面协调点,显著影响O2的激活和随后的降解路径.
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