Dynamic Equilibrium of Reversible Reactions and Migration of Hydrogen Atoms Mediated by Diffusive Methanol on Rutile TiO2 (110)-(1 × 1) Surface

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• 作者：Qijing Zheng ; Shijing Tan ; Hao Feng ; Xuefeng Cui ; Jin Zhao ; Bing Wang
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：April 14, 2016
• 年：2016
• 卷：120
• 期：14
• 页码：7728-7735
• 全文大小：558K
• 年卷期：0
• ISSN：1932-7455

文摘

We report our investigation of the reversible reaction of methanol and the migration of hydrogen adatom (H_ad) on TiO₂(110)-(1 × 1) surface at various temperatures and methanol coverages using scanning tunneling microscopy joint with density functional theory (DFT) calculations. At a relatively low coverage measured at room temperature, the methanol species adsorbed at the oxygen vacancy (O_V) sites are immobile and appear only as a dissociative form, and the observed H_ad migration events are very few. However, when the O_V sites are fully filled by methanol in the methanol-overdosed sample, the methanol species at the O_V sites keep immobile but frequently switch between molecular and dissociative forms, accompanied by dramatically enhanced H_ad migration. Meanwhile, an established equilibrium shows a concentration ratio of 1:3 between the molecular and dissociative methanol. At 235 K, we directly visualized and confirmed that the reversible reactions of methanol and the enhanced H_ad migration are mediated by the diffusive methanol adsorbed at the 5-fold coordinated Ti sites. Our DFT calculations well elucidate the experimental results using the modeled configurations by considering the exchange processes of H atoms, reaching a clear atomistic picture for the dynamic equilibrium of the reversible reactions and the H_ad migration.