Hydrogen Bonding Controls the Dynamics of Catechol Adsorbed on a TiO2(110) Surface
Hydrogen Bonding Controls the Dynamics of Catechol Adsorbed on a TiO2(110) Surface
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氢键控制 TiO2(110) 表面吸附儿茶酚的动力学
DOI：
10.1126/science.1188328
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发表时间：
2010-05-14
期刊：
影响因子：
56.9
通讯作者：
Diebold, Ulrike
中科院分区：
文献类型：
--
作者：
Li, Shao-Chun;Chu, Li-Na;Diebold, Ulrike
氧化物表面的停止或继续使用扫描隧道显微镜（STM）等仪器对表面扩散的直接研究通常集中在金属表面的物种上，但表面扩散对金属氧化物表面的反应起着重要作用。Li等人（第882页）使用STM和密度泛函理论计算来研究邻苯二酚（带有两个−OH基团的苯环）如何在二氧化钛的金红石相表面上扩散。移动的和非移动的物质都在分钟的时间尺度上观察到，同时进行重复的STM扫描。氢原子在表面OH基团和分子之间的转移改变了分子和表面之间的相互作用能，从而改变了扩散的势垒。羟基化金属氧化物表面上的有机分子的扩散势垒取决于氢键的形成。直接研究有机分子如何在金属氧化物表面扩散可以为催化和分子组装过程提供见解。我们研究了单个儿茶酚分子，C6H4（OH）2，金红石型TiO 2（110）表面与扫描隧道显微镜。表面羟基增强吸附的儿茶酚类的扩散。质子的捕获和释放导致单个分子在几分钟的测量周期内在移动的和非移动的状态之间切换。密度泛函理论计算表明，氢从表面羟基转移到分子及其与表面羟基的相互作用大大降低了整个表面的旋转运动的活化势垒。氢键在分子组装动力学的初始阶段起着至关重要的作用。
Stop or Go on Oxide Surfaces Direct studies of surface diffusion with instruments such as the scanning tunneling microscope (STM) have often focused on species on metal surfaces, but surface diffusion can play an important role for reactions on metal oxide surfaces. Li et al. (p. 882) used STM and density functional theory calculations to study how catechol (a benzene ring bearing two −OH groups) diffuses on the surface of the rutile phase of titanium dioxide. Both mobile and immobile species were observed on the time scale of minutes while making repeated STM scans. Hydrogen atom transfers between surface OH groups and the molecule changed the interaction energy between the molecule and the surface, and hence the barrier for diffusion. The diffusion barrier for an organic molecule on a hydroxylated metal oxide surface depends on hydrogen bond formation. Direct studies of how organic molecules diffuse on metal oxide surfaces can provide insights into catalysis and molecular assembly processes. We studied individual catechol molecules, C6H4(OH)2, on a rutile TiO2(110) surface with scanning tunneling microscopy. Surface hydroxyls enhanced the diffusivity of adsorbed catecholates. The capture and release of a proton caused individual molecules to switch between mobile and immobile states within a measurement period of minutes. Density functional theory calculations showed that the transfer of hydrogen from surface hydroxyls to the molecule and its interaction with surface hydroxyls substantially lowered the activation barrier for rotational motion across the surface. Hydrogen bonding can play an essential role in the initial stages of the dynamics of molecular assembly.