High Aspect Ratio of Silver Nanowires for Ultralow Chemical Concentration Detection via Surface-Enhanced Infrared Absorption Spectroscopy

Plasmonic nanomaterials (Au, Ag, Pt, and Cu) have attracted attention for enhanced spectroscopic sensing applications. Different approaches have been developed for nanostructure synthesis. In this study, high aspect ratio silver nanowires were successfully synthesized using the polyol method. During the preparation step, iron (III) chloride was introduced as a catalytic agent to help the nanowires development. The influence of FeCl3 reduction time on the morphology and plasmonic behavior of silver nanowires was systematically investigated. The UV-Vis spectra of silver nanowires presented a main absorption peak around 400 nm and a prominent shoulder around 350 nm. Scanning electron microscopy images confirmed the micrometer-scale lengths and narrow diameters. Furthermore, low-cost Surface-Enhanced Infrared Absorption Spectroscopic substrates were fabricated by depositing silver nanowires onto filter paper. Owing to the strong localized surface plasmon resonance of metallic nanostructures, the silver nanowires-based substrates enabled ultrasensitive detection of Eosin Y down to 10 ppb. The study highlighted the key role of iron (III) chloride in silver nanowire synthesis and demonstrated the facile economical preparation of silver nanowire-on filter-paper substrates as chemical sensors for trace-level detection.