Effect of hot electron induced charge transfer generated by surface plasmon resonance on Ag@Au/ITO/PNTP systems

The present study discusses the fabrication of a bimetallic material consisting of silver nanorods and gold nanospheres (designated Ag@Au), and its surface modification with 4-nitrothiophenol (PNTP) after deposition on an indium tin oxide (ITO) glass sheet, followed by laser irradiation at various wavelengths. The results indicate that the reduction of PNTP is more complete under irradiation at 532 nm due to the surface plasmon resonance (SPR) effects of the gold and silver nanomaterials. Moreover, the surface enhanced Raman scattering (SERS) of the PNTP adsorbed on the Ag@Au/ITO is found to be significantly stronger than that of PNTP adsorbed on Ag@Au alone, due to charge transfer (CT) at the interface. In addition, the SERS enhancement effect of the PNTP molecules on the Ag@Au/ITO substrate is optimal under 532 nm laser irradiation due to the hot electron-induced CT generated by the SPR effect. Thus, the system constructed herein combines the effects of SPR and CT, thereby assisting in a further understanding of the enhancement mechanism of SERS and, hence, the further development SERS research in metal-semiconductor-molecular systems.