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首页> 外文期刊>Chemistry: A European journal >Unravelling the Relationship between Raman Enhancement and Photocatalytic Activity on Single Anisotropic Au Microplates
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Unravelling the Relationship between Raman Enhancement and Photocatalytic Activity on Single Anisotropic Au Microplates

机译：揭开单个各向异性金微板上拉曼增强与光催化活性之间的关系

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摘要

Anisotropic noble-metal structures are attracting increasing attention because of interesting size- and shapedependent properties and have emerging applications in the fields of optics and catalysis. However, it remains a significant challenge to overcome chemical contributions and acquire molecular insight into the relationship between Raman enhancement and photocatalytic activity. This study gives visualized experimental evidence of the anisotropic spatial distribution of Raman signals and photocatalytic activity at the level of single nanometer-thin Au microtriangles and microhexagons. Theoretical simulations indicate an anisotropic spatial distribution and sharpness-dependent strength of the electric-field enhancement. Analysis by using statistical surface- enhanced Raman scattering (SERS) supports this view, that is, Raman enhancement is on the order of corner> edge>face for a single microplate, but SERS measurements at different depths of focus also imply a concentration-dependent feature of SERS signals, especially at the corners and edges. Similarly, the SERS signals of product molecules in plasmonic photocatalysis also exhibit asymmetrical strengths at different corners of the same microplate. However, by examining the variations in the relative intensities of the SERS peaks, the difference in the photocatalytic activities at the corners, edges, and faces has been successfully calculated and is highly consistent with electric-field simulations, thus indicating that an increased number of molecules adsorbed at specific sites does not necessarily lead to a higher conversion ratio in noble-metal photocatalysis. Our strategy weakens the assumed impact of plasmonic local heating and, to a certain extent, excludes the influence of concentration effects and chemical contributions in noble-metal photocatalysis, thus clearly profiling plasmon-related characteristics. This study also promises a new research direction to understand the enhancement mechanism of SERS-active structures.
机译：各向异性的贵金属结构因其有趣的尺寸和形状依赖性而受到越来越多的关注，并在光学和催化领域中得到了新兴应用。然而，克服化学作用并获得对拉曼增强和光催化活性之间关系的分子认识仍然是一项重大挑战。这项研究提供了可视化的实验证据，证明了拉曼信号的各向异性空间分布和在单个纳米级金Au微三角形和微六角形水平上的光催化活性。理论仿真表明，电场增强具有各向异性的空间分布和与锐度有关的强度。通过使用统计表面增强拉曼散射（SERS）进行的分析支持此观点，即，单个微孔板的拉曼增强顺序为角>边>面，但是在不同焦点深度处的SERS测量也暗示了浓度依赖性SERS信号的特征，特别是在拐角和边缘。同样，等离激元光催化过程中产物分子的SERS信号在同一微孔板的不同角上也显示出不对称强度。但是，通过检查SERS峰相对强度的变化，已成功计算了拐角，边缘和表面的光催化活性差异，并且与电场模拟高度一致，因此表明吸附在特定位置的分子不一定会在贵金属光催化中导致更高的转化率。我们的策略削弱了等离子体激元局部加热的假定影响，并在一定程度上排除了贵金属光催化中的浓度效应和化学贡献的影响，从而清晰地描述了等离子体激元相关的特性。这项研究也为理解SERS活性结构的增强机理提供了新的研究方向。

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