Simple strategy for preparing nanoporous silver sheets as reusable SERS substrates for trace analysis with up to 60 reuses

Leveraging fingerprint-like specificity of molecular vibrations and enhanced sensitivity from metallic nanostructures, surface-enhanced Raman spectroscopy (SERS) has emerged as a powerful analytical tool. However, most SERS substrates are designed for disposable single-use, which compromises data reproducibility, increases operational costs, raises sustainability concerns, and narrows practical applications. Furthermore, the complex fabrication methods of existing reusable SERS substrates and their limited recycling/reusable cycles pose significant challenges to address the needs of automated high-throughput analytical applications. In this study, we developed a novel nanoporous silver sheet as a background-free, highly sensitive, and reusable SERS platform, using a simple chemical redox method. With multiple layers of uniform coral rock-like nano-silver rods, it demonstrated excellent sensitivity with a detection limit of 1 × 10⁻⁷ M (24 ppb) for thiram and universal detection capability across a diverse range of 10 pesticides, such as carbamates, organophosphorus compounds, pyrethroids, organochlorines, and benzimidazoles, which was further validated through practical testing on yellow cabbages. More importantly, this nanoporous silver sheet could be reused at least 60 times from a straightforward rinsing procedure to maintain its consistently outstanding performance for continues SERS measurements. Given its accessibility and economic viability, this highly reusable SERS substrate holds the promise to promote the practical applications of SERS in various fields in the future.