Engineering metal oxide semiconductor nanostructures for enhanced charge transfer: fundamentals and emerging SERS applications

Abstract

There is a growing interest in semiconductor nanomaterials for their potential applications as ultrasensitive surface enhanced Raman scattering (SERS) substrates in various fields. SERS has become a powerful tool for sensing in chemical and biochemical analyses. In addition to the traditional noble metal-based SERS substrates, recent progress in semiconductor research on SERS sensitivity has shown emerging and novel materials design strategies. However, controlled and effective engineering strategies are desired to tailor their optoelectronic and charge transfer (CT) properties for high performance SERS activity. In this review, doping engineering of semiconductors, particularly metal oxide nanostructures, to enhance their CT properties for excellent SERS activity are reported. Because of the additional functionalities of metal oxides as photocatalysts, doping engineering provides significant opportunities to tailor their recyclability, allowing highly sensitive SERS detection of multiple species and providing an understanding of the fundamentals of molecular interactions at such interfaces. This review provides details on the fundamentals of doping engineering strategies of metal oxide nanomaterials and various CT processes for emerging SERS applications with an emphasis on doping induced structural/optoelectronic changes, defects, and improved CT mechanisms. Furthermore, future possibilities and development of novel semiconductor materials as emerging SERS substrates have also been discussed.