摘要
金属的催化性能很大程度上取决于其表面结构,金属的表面结构不同带来的催化活性也不一样。我们最近报道的重构的金(110)表面可以催化正构烷烃的端甲基和紧邻亚甲基的C-H键,并促使烷烃分子发生线性聚合[1]。但是对于金(110)的(1×2)重构表面还是(1×3)重构表面在反应中起决定性的催化作用还不清楚。基于这一问题,我们利用扫描隧道显微镜、低能电子衍射和密度泛函理论系统地研究了正构烷烃在金(110)表面的聚合反应。利用低能电子束辐照样品,在覆盖了直链烷烃分子的金(110)表面人为地构筑出局部的(1×3)重构区域,通过加热样品发现(1×3)重构区域的分子比(1×2)区域的分子更易聚合。同时,DFT计算也表明烷烃分子在(1×3)区域比(1×2)区域具有更低的反应活化能。通过这些比较,我们提出金(110)的(1×3)重构表面对于直链烷烃分子具有更好的催化活性。
Catalytic performance of metals depends remarkably on its surface structure.Different surface structures of the metal catalyst appear different catalytic activity.Our recent report on the polymerization of normal alkanes on reconstructed Au(110) surfaces documents an unconventional gold catalysis on the activation of C-H bonds.However,it still remains a question on the real active site of the reconstructed Au(110),since the reconstructed structure of Au(110) has been shifted from(1?2) to(1?3) after alkane polymerization.We have systematically investigated the polymerization of dotriacontane on Au(110) surfaces by means of scanning tunneling microscopy(STM),low energy electron diffraction(LEED) and density functional theory(DFT) simulations.An artificial way to locally control the reconstructed structures of the Au(110) has been successfully developed by applying low energy electrons radiation.Both STM and DFT simulations indicate that dotriacontane molecules are more active on the(1?3)-Au(110) surface.
引文
[1]Zhong,D.;Franke,J.;Podiyanachari,S.;Bl?mker,T.;Zhang,H.;Kehr,G.;Erker,G.;Fuchs,H.;Chi,L.Science 2011,334:213.