Branched silver nanowires on fluorine-doped tin oxide glass for simultaneous amperometric detection of H2O2 and of 4-aminothiophenol by SERS

This study introduces a two-step method for the deposition of branched silver nanowires (AgNWs) on fluorine-doped tin oxide (FTO) glass. This material serves as both an active surface-enhanced Raman-scattering (SERS) substrate and as an enzyme-free electrochemical sensor for H2O2. This dual functionality is systematically studied. The AgNWs as the main trunk were first deposited on FTO by spray-coating. Silver branches were then electrochemically produced on the preformed NWs. Scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectrometry were employed to characterize morphology, composition and microstructure. SERS experiments show that the branched AgNW/FTO substrate exhibits excellent performance in detecting 4-aminothiophenol at an ultra-low concentration of 0.1 fM. Simultaneously, this material displays an excellent electrocatalytic response to H2O2 reduction at a concentration as low as 1 mu M. The sensor has a rapid response and two linear analytical ranges that extend from 0.25 to 300 mu M, and from 0.3 to 2.6 mM of H2O2, respectively. The ultrahigh sensitivity and satisfactory reproducibility highlights the merit of this hierarchical AgNW dendritic structure for sensing applications.