Plasmon-induced hot electrons drive in situ Ag nanoparticles generation on 3D nanostructures for amplified surface enhanced raman scattering activity

Surface Enhanced Raman Scattering (SERS) substrates with high sensitivity and uniformity have been achieved using metallic plasmonic nanostructure arrays. There is a growing demand for cost-effective, ordered SERS-active nanostructures in portable detection. This study presents an efficient strategy for scalable fabricating low-cost, highly sensitive SERS substrates through a hot-electron-assisted reduction mechanism. Two sequential steps are involved: first, depositing an Au film onto an anodic aluminum oxide (AAO) template to create a 3D plasmonic nanostructure; second, in situ formation of Ag nanoparticles on the Au-coated AAO via plasmon-induced hot-electron reduction of silver nitrate under light excitation, eliminating the need for additional heating. The composite substrate demonstrates a 10⁴-fold Raman enhancement for low-concentration Rhodamine B detection, with a relative standard deviation of merely 2.3–4.7%. Moreover, a favorable linear relationship between the logarithm of SERS intensity (LogI) and logarithm of Rhodamine 6 G concentration (LogC) is observed with the Coefficient of Determination (R 2 ) reaching 0.99. It also serves as an effective catalytic template for 4-nitrobenzenethiol photoreactions, monitored via SERS spectral changes. Benefiting from distinct plasmonic signal enhancement, the Ag–Au/AAO substrate is competent for diverse analytical tasks, ranging from standard dye probes and trace paraquat pesticides to clinical clozapine pharmaceuticals, demonstrating broad applicability in environmental and biomedical sensing. Download: Download high-res image (298KB) Download: Download full-size image