Infrared Spectra of Photoinduced Species on Hydroxylated Titania Surfaces
Infrared Spectra of Photoinduced Species on Hydroxylated Titania Surfaces
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DOI：
10.1021/jp0007890
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发表时间：
2000-10
影响因子：
3.3
通讯作者：
Steven H. Szczepankiewicz;A. Colussi;M. Hoffmann
中科院分区：
文献类型：
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作者：
Steven H. Szczepankiewicz;A. Colussi;M. Hoffmann
我们检测瞬态和持久的漫反射红外信号从表面中间体产生的带隙照射的多晶，羟基化的二氧化钛在受控气氛下。在真空中或在CD 3 OD（ads）存在下的辐照导致在3716 cm-1处的新吸光度、3647 cm-1带的下降和反射率损失。测量移动的电荷的总反射率在黑暗中几分钟后部分恢复，但在暴露于O2时完全恢复。3716 cm-1的特征在真空或干燥O2中持续数天，但在（O2 + H2O + hν）的作用下被漂白。它归属于Ti（III）O−H-振动，由酸性Ti（IV）OH中心的电子捕获产生。在O2下的辐照产生了一个位于3683 cm-1的新谱带，归因于在真空中无限期存在的表面结合OH自由基。在随后暴露于H2O（g）的热生成TiO 2-γ样品上没有发生上述事件。我们推断：（1）O_2是导带电子的有效清除剂。
We detect transient and persistent diffuse reflectance infrared signals from surface intermediates generated by band gap irradiation of polycrystalline, hydroxylated TiO2 under controlled atmospheres. Irradiation in vacuo or in the presence of CD3OD(ads) leads to a new absorbance at 3716 cm-1, the decline of a 3647 cm-1 band, and a reflectivity loss. Overall reflectivity, which gauges mobile charge, partially recovers in the dark after a few minutes but fully recovers upon exposure to O2. The 3716 cm-1 feature persists for days in a vacuum or dry O2 but is bleached by the action of (O2 + H2O + hν). It is assigned to a Ti(III)O−H- vibration resulting from electron trapping at acidic Ti(IV)OH centers. Irradiation under O2 yields a new band at 3683 cm-1, ascribed to surface-bound OH radicals that last indefinitely in a vacuum. None of the above events occur on thermally generated TiO2-γ specimens subsequently exposed to H2O(g). We infer that (1) O2 is an efficient scavenger of conduction band electrons at th...