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首页> 外文期刊>Journal of the American Chemical Society >Electric Field Changes on Au Nanoparticles on Semiconductor Supports - The Molecular Voltmeter and Other Methods to Observe Adsorbate-Induced Charge-Transfer Effects in Au/TiO_2 Nanocatalysts
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Electric Field Changes on Au Nanoparticles on Semiconductor Supports - The Molecular Voltmeter and Other Methods to Observe Adsorbate-Induced Charge-Transfer Effects in Au/TiO_2 Nanocatalysts

机译：半导体载体上金纳米粒子的电场变化-分子伏特计和观察吸附剂诱导的Au / TiO_2纳米催化剂中电荷转移效应的其他方法

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摘要

Infrared (IR) studies of Au/TiO_2 catalyst particles indicate that charge transfer from van der Waals-bound donor or acceptor molecules on TiO_2 to or from Au occurs via transport of charge carriers in the semiconductor TiO_2 support. The △ν_(CO) on Au is shown to be proportional to the polarizability of the TiO_2 support fully covered with donor or acceptor molecules, producing a proportional frequency shift in ν_(CO). Charge transfer through TiO_2 is associated with the population of electron trap sites in the bandgap of TiO_2 and can be independently followed by changes in photo-luminescence intensity and by shifts in the broad IR absorbance region for electron trap sites, which is also proportional to the polarizability of donors by IR excitation. Density functional theory calculations show that electron transfer from the donor molecules to TiO_2 and to supported Au particles produces a negative charge on the Au, whereas the transfer from the Au particles to the TiO_2 support into acceptor molecules results in a positive charge on the Au. These changes along with the magnitudes of the shifts are consistent with the Stark effect. A number of experiments show that the ～3 nm Au particles act as "molecular voltmeters" in influencing △ν_(CO). Insulator particles, such as SiO_2, do not display electron-transfer effects to Au particles on their surface. These studies are preliminary to doping studies of semiconductor-oxide particles by metal ions which modify Lewis acid/base oxide properties and possibly strongly modify the electron-transfer and catalytic activity of supported metal catalyst particles.
机译：Au / TiO_2催化剂颗粒的红外（IR）研究表明，通过半导体TiO_2载体中载流子的传输，电荷从TiO_2上的范德华斯结合的供体或受体分子转移到Au或从Au转移出来。 Au上的△ν_（CO）与完全覆盖有供体或受体分子的TiO_2载体的极化率成正比，从而在ν_（CO）中产生成比例的频移。通过TiO_2进行的电荷转移与TiO_2带隙中的电子陷阱位点的数量有关，并且可以独立地跟随着光致发光强度的变化以及电子陷阱位点的宽红外吸收区的偏移，这也与电子俘获位点成正比。红外激发供体的极化率。密度泛函理论计算表明，电子从供体分子到TiO_2和负载的Au粒子的转移在Au上产生负电荷，而从Au粒子到TiO_2载体到受体分子的转移在Au上产生正电荷。这些变化以及移动幅度与斯塔克效应一致。大量实验表明，〜3 nm的Au颗粒起着影响Δν_（CO）的“分子电压表”的作用。绝缘体颗粒（例如SiO_2）在其表面上没有显示出对Au颗粒的电子转移效应。这些研究对通过修饰路易斯酸/碱氧化物性质并可能强烈改变负载的金属催化剂颗粒的电子转移和催化活性的金属离子进行掺杂研究是初步的。

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  • 来源
    《Journal of the American Chemical Society》 |2015年第5期|1972-1982|共11页
  • 作者

    Monica McEntee; Ana Stevanovic; Wenjie Tang; Matthew Neurock; John T. Yates Jr.;

  • 作者单位

    Department of Chemistry University of Virginia, Charlottesville, Virginia 22904, United States;

    Department of Chemistry University of Virginia, Charlottesville, Virginia 22904, United States;

    Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904, United States;

    Department of Chemistry University of Virginia, Charlottesville, Virginia 22904, United States,Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904, United States;

    Department of Chemistry University of Virginia, Charlottesville, Virginia 22904, United States,Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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