Effects of thermal treatments on the recovery of adsorbed water and photocatalytic activities of TiO2 photocatalytic systems
Effects of thermal treatments on the recovery of adsorbed water and photocatalytic activities of TiO2 photocatalytic systems
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DOI：
10.1021/jp060894v
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发表时间：
2006-04-27
影响因子：
3.3
通讯作者：
Nosaka, Y
中科院分区：
文献类型：
--
作者：
Nosaka, AY;Nishino, J;Nosaka, Y
通过 H-1 NMR 光谱研究了六种不同性质的富含锐钛矿的 TiO2 光催化剂的热处理对再水化过程和光催化活性的影响。乙酸和苯甲酸用于水悬浮液中的光分解。在 973 K 下煅烧后，P25、F4 和 AMT-600 的物理吸附水层恢复相对较快（短于 24 小时），而光催化分解没有显着增强。另一方面，对于 ST-01、UV-100 和 AMT-100，恢复非常缓慢（超过 1 周）且仅部分可逆，并且光催化分解显着增强，但因再水合而延迟。在吸附水存在的情况下，分子的羧基与吸附水的结合被认为与表面的直接吸附竞争，从而减少了直接吸附量，导致光催化效率降低。此外，在所有 TiO2 水悬浮液中，具有芳香环的苯甲酸的光催化分解速度要快得多，并且对于完全脱羟基的 TiO2，其光催化分解效果比乙酸的分解效果更强。这些结果表明最有效的光催化位点应该是 TiO2 表面的疏水位点。从热诱导的表面形貌变化的角度讨论了不同 TiO2 的再水化速率之间的差异。
The effects of thermal treatments on the rehydration process and photocatalytic activity were investigated by H-1 NMR spectroscopy for six anatase abundant TiO2 photocatalysts with different properties. Acetic acid and benzoic acid were employed for photodecomposition in aqueous suspension. After the calcinations at 973 K, physisorbed water layers recovered relatively fast for P25, F4, and AMT-600 (shorter than 24 h) with no significant enhancement of the photocatalytic decomposition. On the other hand, for ST-01, UV-100, and AMT-100, the recovery was very slow (longer than 1 week) and only partially reversible, and the photocatalytic decomposition was considerably enhanced but retarded with rehydration. In the presence of adsorbed water, the binding of a carboxyl group of the molecules with adsorbed water is considered to compete with the direct adsorption on the surface, which reduces the amount of the direct adsorption and results in the reduction in the photocatalytic efficiency. In addition, the photocatalytic decomposition of benzoic acid with an aromatic ring was much faster in all of the TiO2 aqueous suspensions and more enhanced for the fully dehydroxylated TiO2 than that of acetic acid. These results suggest that the most efficient photocatalytic sites should be the hydrophobic sites on the TiO2 surface. The difference among the rehydration rates of different TiO2 is discussed in terms of thermally induced changes of surface morphology.