Design of high-active SERS in 2D Au/TiO₂ thin film for quantitative and photodegraded analysis

Surface-enhanced Raman scattering (SERS) is a highly sensitive and non-destructive analytical technique that has attracted considerable interest in the scientific community. However, the practical application of SERS substrates has been hindered by the limited presence of active hotspots. In this study, we present an approach utilizing a TiO₂ thin film decorated with Au nanoparticles (NPs) as a SERS platform. The Au/TiO₂ hybrid thin film provides the sensor with exceptional sensitivity and remarkable photocatalytic properties for the photodecomposition of target molecules. Consequently, the optimized Au/TiO₂ substrate exhibits a detection limit of 10^–10 M for crystal violet (CV) molecules along with a significant enhancement factor of 1.94 × 10⁸ and reliable repeatability. Additionally, it demonstrates a retention rate of 90% after three photodegradation cycles, highlighting its impressive reusability. Over a period of 45 days, the SERS intensity shows only a slight decrease of approximately 10%, underscoring its robust stability. The superior performance of our hybrid sample can be attributed to two primary benefits: the plasmonic effect of the Au NPs, which significantly enhances SERS sensitivity, and the charge-transfer (CT) effect, which enables facilitating efficient self-cleaning through the photocatalytic degradation of the TiO₂ thin film under ultraviolet light exposure. This study not only offers insights into the synergistic effects of the electromagnetic enhancement and CT for recyclable SERS, but also opens up new avenues for studying photocatalysis involving dye molecules and monitoring catalytic processes.