Fritz-Haber-Institut der MPG, Faradayweg 4-6, D-14195 Berlin, Germany.
J Am Chem Soc. 2012 Feb 8;134(5):2532-4. doi: 10.1021/ja211396t. Epub 2012 Jan 27.
Using scanning tunneling microscopy, we have investigated how the doping of CaO thin films affects the growth behavior of gold. Whereas 3D deposits develop on pristine films, 2D islands form after inserting 4% of Mo into the CaO lattice. Adding small amounts of Li to the Mo-doped CaO reinstalls the initial 3D growth regime. We assign this morphology crossover to charge transfer processes between the dopants and the ad-metal. Whereas Mo acts as an electron donor and provides excess charges to be transferred into the gold, Li creates electron traps in the oxide lattice that interrupt the charge flow toward the metal. The different Au charge states in the presence of the dopants are derived from different growth morphologies with anionic gold favoring a 2D mode due to an enhanced interface adhesion. Our work demonstrates how oxide doping can be exploited to tailor the equilibrium geometry of ad-particles on supported metal catalysts.
我们使用扫描隧道显微镜研究了 CaO 薄膜的掺杂如何影响金的生长行为。在原始薄膜上形成 3D 沉积物，而在 CaO 晶格中插入 4%的 Mo 后则形成 2D 岛。向 Mo 掺杂的 CaO 中添加少量 Li 可以重新安装初始的 3D 生长状态。我们将这种形态交叉归因于掺杂剂和吸附金属之间的电荷转移过程。Mo 充当电子供体并提供多余的电荷以转移到金中，而 Li 在氧化物晶格中产生电子陷阱，从而中断电荷流向金属。在掺杂剂存在下，Au 的不同电荷状态源于不同的生长形态，由于界面附着力增强，阴离子 Au 有利于 2D 模式。我们的工作表明，如何利用氧化物掺杂来调整负载金属催化剂上吸附粒子的平衡几何形状。
