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首页> 外文期刊>Environmental Science & Technology >The Myth of Visible Light Photocatalysis Using Lanthanide Upconversion Materials
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The Myth of Visible Light Photocatalysis Using Lanthanide Upconversion Materials

机译：镧系上转换材料在可见光催化下的神话

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摘要

Upconversion luminescence is a nonlinear optical process achieved by certain engineered materials, which allows conversion of low energy photons into higher energy photons. Of particular relevance to environmental technology, lanthanide-based upconversion phosphors have appeared in dozens of publications as a tool for achieving visible light activation of wide-band gap semiconductor photocatalysts, such as TiO_(2), for degradation of water contaminants. Supposedly, the phosphor particles act to convert sub-band gap energy photons (e.g., solar visible light) into higher energy ultraviolet photons, thus driving catalytic aqueous contaminant degradation. Herein, however, we reexamined the photophysical properties of the popular visible-to-UV converters Y_(2)SiO_(5):Pr~(3+) and Y_(3)Al_(5)O_(12):Er~(3+), and found that their efficiencies are not nearly high enough to induce catalytic degradations under the reported excitation conditions. Furthermore, our experiments indicate that the false narrative of visible-to-UV upconversion-sensitized photocatalysis likely arose due to coincidental enhancements of dye degradation via direct electron injection that occur in the presence of dielectric-semiconductor (phosphor-catalyst) interfaces. These effects were unrelated to upconversion and only occurred for dye solutions illuminated within the chromophore absorption bands. We conclude that upconversion using Pr~(3+) or Er~(3+)-activated systems is not a technologically appealing mechanism for visible light photocatalysis, and provide experimental guidelines for avoiding future misinterpretation of these phenomena.
机译：上转换发光是通过某些工程材料实现的非线性光学过程，可将低能光子转换为高能光子。与环境技术特别相关的是，基于镧系元素的上转换磷光体已在数十种出版物中用作实现宽带隙半导体光催化剂（例如TiO_（2））的可见光活化以降解水污染物的工具。据推测，磷光体颗粒起到将亚带隙能量光子（例如，太阳可见光）转换成较高能量的紫外光子的作用，从而促使催化性水污染物降解。然而，在这里，我们重新检查了流行的可见-紫外转换器Y_（2）SiO_（5）：Pr〜（3+）和Y_（3）Al_（5）O_（12）：Er〜（ 3+），发现它们的效率还不够高，不足以在报道的激发条件下引起催化降解。此外，我们的实验表明，在介电半导体（磷-催化剂）界面的存在下，通过直接电子注入同时发生的染料降解同时增加，可能导致对可见光-UV上转换增敏的光催化的错误叙述。这些作用与上转换无关，仅在发色团吸收带内照射的染料溶液中发生。我们得出结论，使用Pr〜（3+）或Er〜（3+）激活系统进行上转换不是可见光光催化技术上有吸引力的机制，并提供了避免将来对这些现象的误解的实验指导。

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  • 来源
    《Environmental Science & Technology》 |2018年第5期|2973-2980|共8页
  • 作者

    SushantP. Sahu; Stephanie L. Cates; Hyoung-Il Kim; Jae-Hong Kim; Ezra L. Cates;

  • 作者单位

    Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634, United States;

    Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States;

    Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States;

    Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States;

    Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634, 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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