Low-cost, washable, and highly reusable Ag nanoparticle surface-enhanced Raman scattering substrates

Recently, the reusability of surface-enhanced Raman scattering (SERS) substrates has gained significant research attention, offering great potential to expand SERS applications. The high fabrication costs and time constraints have driven the development of reusable substrates. Ag nanoparticles (NPs) with nanogaps are widely used as SERS substrates because of their ability to excite strong localized surface plasmon coupling. However, developing a facile method for producing reusable Ag NP SERS substrates remains challenging. In this study, we introduce a rapid and cost-effective method for mass-producing Ag NPs using a two-step process: Spin coating a self-reducing solution, followed by heating treatment. This method enables the mass production of Ag NPs with nanogaps as small as approximately 10 nm, eliminating the need for a vacuum environment, expensive equipment, or complex processing steps. The formation mechanism of Ag NPs is briefly discussed, and the key factors for successful preparation are highlighted. The resulting Ag NPs exhibit superior SERS performance, uniformity, and sensitivity. They functioned as washable and highly reusable SERS substrates, showing no significant performance loss after four ultrasonic cleaning cycles. Even after ten cycles, over 60% of the initial SERS performance was retained, demonstrating their robustness and practical applicability.