Deciphering the Optical Absorption Spectra of Ultrafine Metal Nanoparticles Dispersed on Submicron Silica Spheres
Deciphering the Optical Absorption Spectra of Ultrafine Metal Nanoparticles Dispersed on Submicron Silica Spheres
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DOI：
10.1021/acs.jpcc.2c04303
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
Qilin Wei;Matas Simukaitis;Siyu Wu;J. Foley;Yugang Sun
中科院分区：
文献类型：
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作者：
Qilin Wei;Matas Simukaitis;Siyu Wu;J. Foley;Yugang Sun
金属纳米颗粒在不吸收光的介质载体上的光吸收由于介质载体的光散射的卷积而变得复杂。确定金属/介电复合材料光吸收特性的来源，对于设计具有良好光吸收性能的材料，如光催化等，是至关重要的。在这项工作中，我们利用吸收灵敏的漫反射光谱(DRS)和理论模拟/计算，系统地研究了二氧化硅微球负载的超细金属纳米粒子(SiOx-SPS)的光吸收。实验测量和理论预测的比较表明，ufMNPs/SiOx-SP复合粉末中的SiOx-SPS表现出三种类型的散射，以确定负载的ufMNPs的光吸收。首先，单个尺寸较大的SiOx-SPS表面附近的局域光散射共振产生了增强的电场，从而促进了峰清晰的ufMNPs的强光吸收。第二，从单个尺寸较小的SiOx-SPS散射的非单向漫反射光穿透被ufMNPs吸收的复合粉末，表现出上坡和无峰的吸收曲线。第三，漫反射光可以通过复合颗粒的有序堆积来调制，这些复合颗粒在阻带表现出光子反射，导致复合粉末的DRS光谱出现凹陷。UfMNPs/SiOx-SP复合粒子中光吸收的反卷积为合理设计具有良好光吸收性能的复合材料开辟了一条途径，例如局域吸收的非线性和漫反射的线性。
Optical absorption of metal nanoparticles on dielectric supports that do not absorb light becomes complicated due to the convolution of light scattering of the dielectric supports. Identifying the origin of optical absorption characteristics in metal/dielectric composite materials is vital to designing materials with desirable optical absorption properties for interesting applications such as photocatalysis. In this work, we systematically investigated the optical absorption of ultrafine metal nanoparticles (ufMNPs) supported on silica spheres (SiOx-SPs) using absorption-sensitive diffuse reflectance spectroscopy (DRS) and theoretical modeling/calculations. The comparisons between experimental measurements and theoretical predictions reveal that the SiOx-SPs in ufMNPs/SiOx-SP composite powders exhibit three types of scattering to determine the optical absorption of the supported ufMNPs. First, localized light-scattering resonances near the surface of individual SiOx-SPs with large sizes generate enhanced electric fields to promote strong optical absorption in the ufMNPs with well-defined peaks. Second, nonunidirectional diffuse light scattered from individual SiOx-SPs with relatively small sizes penetrates the composite powders to be absorbed by the ufMNPs, exhibiting uphill and peakless absorption profiles. Third, the diffuse light can be modulated by the ordered packing of the composite particles that exhibit photonic reflection at the stop band, resulting in a valley in the DRS spectrum of a composite powder. The deconvolution of optical absorption in the ufMNPs/SiOx-SP composite particles opens an avenue to rationally design composite materials with favorable light absorption properties, for example, nonlinearity of localized absorption versus linearity of diffuse absorption.