Light-driven in situ deposited Au nanoparticles on ZnO substrate with ultrasensitive SERS enhancement for molecular...

Uniform, reproducible and stable SERS substrates with high detection sensitivity are crucial for their successful commercial applications. Here, we introduce a plasmonic SERS substrate based on gold nanoparticles (AuNPs) fabricated by using a straightforward light-driven in-situ method for highly sensitive molecular detection. A dense array of zinc oxide nanorods (ZnO NRs) was used as a support surface for the in-situ growth of Au nanoparticles (AuNPs). The SERS performance of the fabricated Au-ZnO substrates was evaluated by using rhodamine 6G (R6G) dye as a model Raman probe, where the distribution of the AuNPs on the substrate was found to play an important role defining the SERS activities The Au-ZnO substrates exhibited exceptional homogeneity (RSD = 3.95%), a detection limit (LOD) of 9 × 10^-11 M, and signal enhancement in the order of 10⁶. Additionally, these substrates demonstrated good stability over a period of 4 weeks when stored under standard room conditions, maintaining more than 80% of the initial Raman signal intensity. When tested for antibiotic residue detection in water using amoxicillin as a model antibiotic, the Au-ZnO substrates revealed LOD in the order of 10^-9 M with linear detection over a wide concentration range of amoxicillin in water. The present work offers a straightforward and inexpensive solution-processed fabrication approach for SERS substrates that holds great potential for the development of extremely sensitive and reliable SERS-based detection and sensor systems.