Abstract

The catalytic activity of silver nanoparticles (AgNPs) on a germanium substrate is reported. <i>Para</i>-nitrothiophenol (<i>p</i>NTP) that had been adsorbed on this substrate is converted to <i>p</i>-aminothiophenol (<i>p</i>ATP) under very mild reaction conditions, such as simply soaking in water. The AgNPs may be formed either by physical vapor deposition or by electroless deposition from a solution of silver nitrate. Analogous reactions were not observed on copper nanoparticles on germanium or AgNPs on silicon or zinc selenide even though very slow conversion of <i>p</i>NTP to <i>p</i>ATP was observed with Au nanoparticles (AuNPs) on Ge under controlled reaction conditions. The effects of factors that could influence the catalytic reaction were examined; these included the particle size of the AgNPs, reaction temperature, concentration and chemical nature of other ions present in the solution, the pH of the water, and the nature of the substrate. The reaction rate was approximately independent of the particle size for AgNPs between 50 and 150 nm in diameter. Increasing the temperature accelerates the reaction significantly; at temperatures above 40 °C, the adsorbed <i>p</i>NTP is completely converted by water within five minutes. Not surprisingly, the reaction rate was increased as the pH of the solution was decreased, as the reduction of each nitro group to an amino group requires six protons. The presence of Br⁻ and I⁻ ions accelerated the reaction to the point that even at 4 °C, the conversion of the nitro group was still observable, while solutions containing chloride ions had to be heated to 40 °C before their effect became apparent. Apparently, Br⁻ and I⁻ ions remove the oxide layer from the surface of the germanium substrate, facilitating transfer of electrons from the germanium to the nitro group of the pNTP.

High-performance surface-enhanced Raman scattering substrate prepared by self-assembling of silver nanoparticles into the nanogaps of silver nanoislands

Jiamin Quan, Yong Zhu, Jie Zhang, Junyin Li, and Ning Wang
Appl. Opt. 56(20) 5751-5760 (2017)

Surface-enhanced fluorescence from silver fractallike nanostructures decorated with silver nanoparticles

Jun Dong, Hairong Zheng, Xuqiang Li, Xiaoqing Yan, Yu sun, and Zhenglong Zhang
Appl. Opt. 50(31) G123-G126 (2011)

SERS substrate based on the flexible hybrid of polydimethylsiloxane and silver colloid decorated with silver nanoparticles

Yu Guo, Jing Yu, Chonghui Li, Zhen Li, Jie Pan, Aihua Liu, Baoyuan Man, Tianfu Wu, Xianwu Xiu, and Chao Zhang
Opt. Express 26(17) 21784-21796 (2018)

Noble metal modified ReS₂ nanocavity for surface-enhanced Raman spectroscopy (SERS) analysis

Mingrui Shao, Chao Zhang, Jing Yu, Shouzhen Jiang, Xiaofei Zhao, Zhaoxiang Li, Weixi Lu, Baoyuan Man, and Zhen Li
Opt. Express 29(18) 28664-28679 (2021)

Substrate-based platform for boosting the surface-enhanced Raman of plasmonic nanoparticles

Qiao Min, Yuanjie Pang, Daniel J. Collins, Nikita A. Kuklev, Kristy Gottselig, David W. Steuerman, and Reuven Gordon
Opt. Express 19(2) 1648-1655 (2011)