Fabrication of flexible WO3-x nanowires/AgNPs composite on carbon cloth for ultrasensitive surface-enhanced Raman scattering

Noble metal and semiconductor composite substrates possess high sensitivity, excellent stability, and selective enhancement, establishing them as a significant research focus in the field of surface-enhanced Raman scattering (SERS). Tungsten oxide (WO 3 ), as an n-type semiconductor with high thermal stability, corrosion resistance, and outstanding electrochromic properties, has great potential in SERS research. This study designed and fabricated a flexible composite SERS substrate based on oxygen-deficient tungsten oxide nanostructures, achieving optimal detection performance by combining 3D WO 3-x nanowires on carbon cloth (CC) with silver nanoparticles (AgNPs). The high-aspect-ratio WO 3-x nanowires were prepared using a functional group-induced "competitive growth" hydrothermal method. The bandgap was modulated through atmosphere annealing to introduce oxygen vacancies (self-doping), which effectively improved the charge transfer efficiency and surface plasmon resonance, thereby achieving superior SERS performance. This composite SERS substrate benefits from the synergistic contributions of electromagnetic and chemical enhancement mechanisms, achieving ultra-low detection limits of 10 −12 M for Rhodamine 6 G (R6G). Within the concentration range of 10 −7 M to 10 −12 M, there is a good linear relationship between concentration and peak intensity, demonstrating excellent quantitative analysis capabilities. Furthermore, leveraging its mechanical flexibility, this substrate holds broad application prospects in areas such as food safety and environmental monitoring.