Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russia.
Institute of Chemistry and Problems of Sustainable Development, Dmitry Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia.
Int J Mol Sci. 2021 Oct 1;22(19):10673. doi: 10.3390/ijms221910673.
The electron density of a nanoparticle is a very important characteristic of the properties of a material. This paper describes the formation of silver nanoparticles (NPs) and the variation in the electronic state of an NP's surface upon the reduction in Ag ions with oxalate ions, induced by UV irradiation. The calculations were based on optical spectrophotometry data. The NPs were characterized using Transmission electron microscopy and Dynamic light scattering. As ~10 nm nanoparticles are formed, the localized surface plasmon resonance (LSPR) band increases in intensity, decreases in width, and shifts to the UV region from 402 to 383 nm. The interband transitions (IBT) band (≤250 nm) increases in intensity, with the band shape and position remaining unchanged. The change in the shape and position of the LSPR band of silver nanoparticles in the course of their formation is attributable to an increasing concentration of free electrons in the particles as a result of a reduction in Ag ions on the surface and electron injection by CO2- radicals. The ζ-potential of colloids increases with an increase in electron density in silver nuclei. A quantitative relationship between this shift and electron density on the surface was derived on the basis of the Mie-Drude theory. The observed blue shift (19 nm) corresponds to an approximately 10% increase in the concentration of electrons in silver nanoparticles.
纳米粒子的电子密度是材料性质的一个非常重要的特征。本文描述了银纳米粒子（NPs）的形成以及在紫外光照射下，通过草酸盐离子还原Ag 离子时，NP 表面电子态的变化。该计算基于光分光光度法数据。使用透射电子显微镜和动态光散射对 NPs 进行了表征。当形成~10nm 的纳米粒子时，局域表面等离子体共振（LSPR）带的强度增加，宽度减小，从 402nm 移至 383nm 的 UV 区域。带间跃迁（IBT）带（≤250nm）的强度增加，而带的形状和位置保持不变。银纳米粒子在形成过程中 LSPR 带的形状和位置的变化归因于表面 Ag 离子的减少和 CO2-自由基的电子注入导致粒子中自由电子浓度的增加。胶体的 ζ-电势随着银核中电子密度的增加而增加。根据 Mie-Drude 理论推导出了这种位移与表面电子密度之间的定量关系。观察到的蓝移（19nm）对应于银纳米粒子中电子浓度约增加 10%。
