Silver nanowires on coffee filter as dual-sensing functionality for efficient and low-cost SERS substrate and electrochemical detection

A simple dip-coating route to deposit silver nanowires (Ag NW) on coffee filter (CF), which function as a dual sensor for an active surface-enhanced Raman-scattering (SERS) substrate and an electrochemical enzyme-free sensor for H2O2, was systematically investigated. Dip coating for six cycles in a Ag NW colloid solution achieved a conductive and hierarchical Ag NW/CF structure; the morphology and microstructure were examined with a scanning electron microscope, X-ray diffractometer and X-ray photoelectron spectra. The Ag NW/CF electrode shows an excellent electrocatalytic response to H2O2 reduction with significantly small overpotentials, and exhibits also a rapid response and high sensitivity (219 μA cm−2 mM−1) for the amperometric detection of H2O2 in concentration range 100 μM-5.25 mM. With 4-aminothiophenol (4-ATP) as probing molecules, the SERS experiments showed that Ag NW/CF exhibit excellent detection with EF 106, which could serve as effective SERS substrates for ultrasensitive detection (10 pM). This novel and cost-effective Ag NW/CF hierarchical structure shows satisfactory reproducibility and a linear dependence between analyte concentration and detection signal in both sensing applications, revealing the advantage of this method for easily scaled production.