Williams Oscar Bentley Jerdmyr, Katsiev Khabiboulakh, Baek Byeongjin, Harrison George, Thornton Geoff, Idriss Hicham
Department of Chemistry and London Centre for Nanotechnology (LCN), University College London (UCL), WC1H 0AH, London, U.K.
Surface Science and Advanced Characterisation, SABIC-CRD at King Abdullah University for Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia.
J Am Chem Soc. 2022 Jan 19;144(2):1034-1044. doi: 10.1021/jacs.1c12197. Epub 2022 Jan 5.
A new atomic-scale anisotropy in the photoreaction of surface carboxylates on rutile TiO(110) induced by gold clusters is found. STM and DFT+U are used to study this phenomenon by monitoring the photoreaction of a prototype hole-scavenger molecule, benzoic acid, over stoichiometric (s) s-TiO, Au/s-TiO, and reduced (r) Au/r-TiO. STM results show that benzoic acid adsorption displaces a large fraction of Au clusters from the terraces toward their edges. DFT calculations explain that Au clusters on stoichiometric TiO are distorted by benzoic acid adsorption. The influence of sub-monolayers of Au on the UV/visible photoreaction of benzoic acid was explored at room temperature, with adsorbate depletion taken as a measure of activity. The empty sites, observed upon photoexcitation, occurred in elongated chains (2 to 6 molecules long) in the [11̅0] and [001] directions. A roughly 3-fold higher depletion rate is observed in the [001] direction. This is linked to the anisotropic conduction of excited electrons along [001], with subsequent trapping by Au clusters leaving a higher concentration of holes and thus an increased decomposition rate. To our knowledge this is the first time that atomic-scale directionality of a chemical reaction is reported upon photoexcitation of the semiconductor.
发现了金团簇诱导的金红石型TiO(110)表面羧酸盐光反应中的一种新的原子尺度各向异性。通过监测原型空穴清除剂分子苯甲酸在化学计量比(s)的s-TiO、Au/s-TiO和还原态(r)的Au/r-TiO上的光反应，利用扫描隧道显微镜(STM)和密度泛函理论加U(DFT+U)来研究这一现象。STM结果表明，苯甲酸吸附使大部分金团簇从平台向其边缘移动。DFT计算解释了化学计量比TiO上的金团簇因苯甲酸吸附而发生畸变。在室温下，以吸附质消耗作为活性的度量，研究了亚单层金对苯甲酸紫外/可见光光反应的影响。光激发时观察到的空位点出现在[11̅0]和[001]方向上的伸长链中(2至6个分子长)。在[001]方向上观察到的消耗速率大约高3倍。这与激发电子沿[001]方向的各向异性传导有关，随后被金团簇俘获，留下更高浓度的空穴，从而提高了分解速率。据我们所知，这是首次报道半导体光激发时化学反应的原子尺度方向性。
