Photo-reduced WO3/PAN nanofiber membranes with deposited Ag nanoparticles as efficient SERS substrates

Sensitive SERS substrates specified for sensing is highly desired owing to their increasing demand for environment monitoring, disease diagnosis, and chemical analysis. Here, we fabricate amorphous WO3/polyacrylonitrile (WO3/PAN) nanofiber membranes through electrospinning. The photo-reduced NFM show a free carrier concentration up to 1.46 × 1021 cm−3, which is 5 times increased compared with the oxidized NFM and approaching that of the noble metals (2.5 × 1022 cm−3). The detection limit concentration was as low as 10-9 M and SERS enhancement factor can be obtained 0.6 × 105 for the photo-reduced NFM. With in-situ Ag deposition on the surface of the NFM, the SERS enhancement factor can be further increased to 2.9 × 105. More interestingly, since the open structure and high utility of the pores of nanofiber membranes and allow rapid airflow through the membranes, the modified Ag deposited NFMs can be used as SERS substrates for gas sensing with rapid response time (tens of seconds) and low detection limit (10 ppb). Such a simple, low-cost fabrication method to prepare SERS substrate for detecting pollutants in water and gas sensing is promising for future applications.