Chemical Reactivity of Reduced TiO2(110): The Dominant Role of Surface Defects in Oxygen Chemisorption
Chemical Reactivity of Reduced TiO2(110): The Dominant Role of Surface Defects in Oxygen Chemisorption
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DOI：
10.1021/jp901989x
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发表时间：
2009-06
影响因子：
3.7
通讯作者：
N. G. Petrik;Zhenrong Zhang;Yingge Du;Z. Dohnálek;I. Lyubinetsky;G. Kimmel
中科院分区：
文献类型：
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作者：
N. G. Petrik;Zhenrong Zhang;Yingge Du;Z. Dohnálek;I. Lyubinetsky;G. Kimmel
用扫描隧道显微镜、程序升温脱附和电子刺激脱附等方法研究了氧空位(Ov)和桥羟基(OHb)含量不同的金红石型还原二氧化钛(110)对O2的化学吸附。在退火后的表面上，每个Ov可以化学吸附两个氧分子。表面上相同数量的O2化学吸附，其中每个Ov通过暴露在水中被转化为两个OHB(即，每个OHB有1个O2)。通过在室温下将羟化表面暴露在O2中，可以产生很少或没有Ov或OHb的表面，而低温下这些表面上化学吸附的O2的量仅为退火(还原)表面上的∼20%。相反，当OHB浓度增加时，化学吸附的O2的量增加了2倍以上，而不改变亚表面钛间隙的浓度。结果表明，Ti02(110)的反应活性主要受表面给电子体物种的数量控制。
O2 chemisorption on reduced, rutile TiO2(110) with various concentrations of oxygen vacancies (Ov) and bridging hydroxyls (OHb) is investigated with scanning tunneling microscopy, temperature-programmed desorption, and electron-stimulated desorption. On the annealed surface, two oxygen molecules can be chemisorbed per Ov. The same amount of O2 chemisorbs on surfaces where each Ov is converted to two OHb’s by exposure to water (i.e., 1 O2 per OHb). Surfaces with few or no Ov’s or OHb’s can be created by exposing the hydroxylated surface to O2 at room temperature, and the amount of O2 that chemisorbs on these surfaces at low temperatures is only ∼20% of the amount on the annealed (reduced) surface. In contrast, the amount of chemisorbed O2 increases by more than a factor of 2 when the OHb concentration is enhanced—without changing the concentration of subsurface Ti interstitials. The results indicate that the reactivity of TiO2(110) is primarily controlled by the amount of electron-donating surface species ...