Flexible, Graphene Protected Ag Nanoparticles-Polyimide Tape for Use as Transparent Surface-Enhanced Raman Scattering (Sers) Substrate and its Application in Pesticide Detection

A flexible and transparent tape-based SERS substrate consisting of electrodeposited silver nanoparticles (AgNPs) sandwiched between polyimide (PI) tape and graphene (G) layer was successfully fabricated using chemical vapor deposition (CVD) of graphene onto a copper substrate, followed by electrodeposition of Ag nanoparticles, and transferred to PI tape to obtain G/AgNPs/PI SERS substrate. Nanostructure formations on the substrate were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). A rattan ball-like Ag structure with feature gaps of ~30-100nm was obtained from optimized electrodeposition time and current density, which yielded the highest Raman signal enhancement. Methyl parathion (MP) was selected as a probe molecule for investigating the SERS performance where the MP detection limit of 68 ng/cm 2 was achieved. The graphene layer helps to stabilize and protect the Ag nanoparticles. The shelfs life of the G/AgNPs/PI substrate kept at room temperature was extended to be longer than 48 days compared to just 27 days for the SERS without the protective graphene layer. The practicability of this transparent tape-based SERS was successfully demonstrated by detecting the MP residue on an apple fruit where both the light excitation and Raman signal collection were performed from the tape side.