Abstract

The formation of nanoscale gold particles on the surface of an aluminum-oxide film formed on a Mo(110) crystal and the oxidation of carbon-monoxide molecules on their surface are studied in situ in ultrahigh vacuum using Auger electron spectroscopy, low-energy electron diffraction, infrared absorption spectroscopy, atomic force microscopy, temperature-programmed desorption, and work-function measurements. The main focus is on studying the efficiency of the process of oxidation of CO molecules depending on the thickness of the oxide film between Mo and deposited Au particles in order to establish the possible effect of charge tunneling through the oxide-dielectric interlayer on this process. The highest degree of identity of the structural, electronic, and adsorption properties of Au/Al₂O₃/Mo(110) systems is achieved. At different thicknesses of the aluminum-oxide film (2, 4, 6, and 8 single layers), it is shown that the efficiency of the oxidation of CO molecules defined as the fraction of CO₂ molecules relative to CO desorbed into the gas phase during measurements of the thermal-desorption spectra decreases exponentially with an increase in the thickness of the oxide film. Taking into account the established fact that the efficiency of CO oxidation depends on the amount of excess charge acquired by a gold nanoparticle, it can be concluded that charge tunneling through the oxide layer increases the efficiency of the reaction on the surface of the corresponding metal-oxide system.

中文翻译：

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通过氧化膜的电荷隧道效应提高 Au/Al2O3/Mo(110) 金属氧化物体系表面碳氧化物分子的低温氧化活性

摘要

使用俄歇电子能谱、低能电子在超高真空中原位研究了在 Mo(110) 晶体上形成的氧化铝膜表面上纳米级金颗粒的形成及其表面一氧化碳分子的氧化。衍射、红外吸收光谱、原子力显微镜、程序升温脱附和功函数测量。主要重点是研究 CO 分子氧化过程的效率，该过程取决于 Mo 和沉积的 Au 颗粒之间的氧化膜厚度，以确定电荷隧穿穿过氧化物-电介质夹层对该过程的可能影响。_{Au/Al 2} O ₃的结构、电子和吸附性质的最高同一性/Mo(110) 系统得到了实现。在不同厚度的氧化铝膜（2、4、6 和 8 个单层）下，表明 CO 分子的氧化效率定义为 CO ₂分子相对于 CO 解吸到气相中的比例在热解吸光谱的测量过程中，随着氧化膜厚度的增加，光谱呈指数下降。考虑到 CO 氧化效率取决于金纳米粒子获得的过量电荷量这一既定事实，可以得出结论，电荷隧穿通过氧化物层提高了相应金属表面的反应效率 -氧化物系统。