High sensitive SERS film of Ag-coated aggregated nanowire structure and benzene gas detection

Abstract

A highly sensitive surface-enhanced Raman spectroscopy (SERS) film was fabricated based on anodic aluminum oxide template and Ag coating techniques. The array of alumina nanowires of similar to 5 mu m length and 26 nm thickness was fabricated and then made collapse to build a micro-scale funnel array, where each cell consists of hundreds of nanowires. Ag film was deposited on the nanowire structure by thermal evaporation. Due to numerous tapered nanogaps and efficient illumination of incident light in the micro-funnel structures, Raman signal enhancement factor (E.F.) as high as similar to 1.8 x 10(7) could be obtained at 785 nm. The SERS film functionalized by 1-propanethiol was used for benzene gas detection, where the sensitivity of <0.3 ppm (3-sigma) was realized within 120 s. This nanostructure is expected to be widely used for highly sensitive chemical and bio-sensors and have higher E.F. when the morphology is optimized further.