Tailored SiO₂-TiO₂ Aerogel/Ag Flexible Films as Stable SERS Substrates for Hazardous Materials Detection

Flexible surface-enhanced Raman spectroscopy (SERS) substrates have received more and more attention for their non-invasive sample collection ability. However, majority of them have poor stability and reproducibility because noble metal is easily oxidized and led to lose SERS activity. Herein, SiO₂-TiO₂-Ag hybrids aerogel (STAHA) material is first applied as a flexible SERS substrate for explosives and dyes long-term sensitive detection. The sensitive non-invasive detection of 3-nitro-1, 2, 4-triazol-5-one (NTO) residues can be achieved with a limit of 1 × 10⁻⁶ m by wiping sample collection method. Meanwhile, similar SERS sensitivity from long-term (50 days) kept substrates is observed compared with fresh-made substrates. This long-term sensitivity is contributed to electronic transfer compensation from TiO₂ aerogel. This proposed flexible STAHA enrich the type of SERS substrates, and their long-term sensitivity can provide a prospective application for trace analyses of explosives and other hazardous residues in criminal forensic, military, and security check.