Multifunctional Ag nanoparticle decorated Si nanowires for sensing, photocatalysis and light emission applications

Abstract

We report on the fabrication of Ag nanoparticle (NP) decorated mesoporous Si nanowire (NW) heterostructure (HS) by a simple and low cost chemical process. The as-grown Si NWs are mesoporous in nature and the Ag NP decorated Si NWs (Ag@Si NWs) exhibit broadband light emission, ultralow reflectance, efficient photocatalytic degradation of organic dyes and excellent sensitivity for the detection of organic molecules over a wide range of concentration. The broadband white light photoluminescence emission from the bare Si NWs is explained on the basis of quantum confinement effect in Si NCs/NWs and the nonbridging oxygen hole center defects in the SiSiOx interface. High work function of the noble metal NPs facilitates the effective separation of the photoinduced electron-hole pairs in Si NWs, which enables the Ag@Si NWs to exhibit high photocatalytic efficiency for the degradation of organic dye. The Ag@Si NWs exhibited high potential and sensitivity for the selective and quantitative detection of different organic molecules at extremely low concentration down to 10−12 M by surface-enhanced Raman scattering and 10−11 M by fluorescence-based detection. These versatile properties of the Ag@Si NWs open up opportunities for a variety of energy and environmental applications, such as white light emission, solar cell, artificial photosynthesis, disposal of organic pollutant and bio-chemical sensors etc.