Chemical Reactivity of Reduced TiO2(110): The Dominant Role of Surface Defects in Oxygen Chemisorption

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• 作者：Nikolay G. Petrik ; Zhenrong Zhang ; Yingge Du ; Zdenek Dohnlek ; Igor Lyubinetsky ; Greg A. Kimmel
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：July 16, 2009
• 年：2009
• 卷：113
• 期：28
• 页码：12407-12411
• 全文大小：187K
• 年卷期：v.113,no.28(July 16, 2009)
• ISSN：1932-7455

文摘

O₂ chemisorption on reduced, rutile TiO₂(110) with various concentrations of oxygen vacancies (O_v) and bridging hydroxyls (OH_b) is investigated with scanning tunneling microscopy, temperature-programmed desorption, and electron-stimulated desorption. On the annealed surface, two oxygen molecules can be chemisorbed per O_v. The same amount of O₂ chemisorbs on surfaces where each O_v is converted to two OH_b’s by exposure to water (i.e., 1 O₂ per OH_b). Surfaces with few or no O_v’s or OH_b’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 OH_b 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 such as O_v’s and/or OH_b’s, and not Ti³⁺ interstitials.