Electron traps and their effect on the surface chemistry of TiO2 (110)
Electron traps and their effect on the surface chemistry of TiO2 (110)
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DOI：
10.1073/pnas.0911349107
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发表时间：
2010-02-09
影响因子：
11.1
通讯作者：
Thornton, Geoff
中科院分区：
文献类型：
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作者：
Papageorgiou, Anthoula C.;Beglitis, Nikolaos S.;Thornton, Geoff
长期以来，金属氧化物表面的氧空位一直被认为在表面化学中发挥关键作用。在模型光催化剂表面TiO 2（110）与水和分子氧反应的情况下，这些过程已经被直接可视化。这些空缺已被假定为中性的表面性能的计算。然而，通过比较实验和模拟的扫描隧道显微镜图像和光谱，我们表明，氧空位作为捕获中心，并带负电荷。我们表明，充电的缺陷显着影响的反应性，通过以下的反应分子氧与表面羟基形成的水解离的空缺。计算与带电的羟基有利于缩合反应形成水和表面的氧吸附原子，与实验观察。这与使用中性羟基的模拟形成对比，其中发现过氧化氢是最稳定的产物。
Oxygen vacancies on metal oxide surfaces have long been thought to play a key role in the surface chemistry. Such processes have been directly visualized in the case of the model photocatalyst surface TiO2 (110) in reactions with water and molecular oxygen. These vacancies have been assumed to be neutral in calculations of the surface properties. However, by comparing experimental and simulated scanning tunneling microscopy images and spectra, we show that oxygen vacancies act as trapping centers and are negatively charged. We demonstrate that charging the defect significantly affects the reactivity by following the reaction of molecular oxygen with surface hydroxyl formed by water dissociation at the vacancies. Calculations with electronically charged hydroxyl favor a condensation reaction forming water and surface oxygen adatoms, in line with experimental observations. This contrasts with simulations using neutral hydroxyl where hydrogen peroxide is found to be the most stable product.