Highly Sensitive, Cost‐Effective, and Flexible SERS Substrate Based on Green Synthesized GO/rGO for Pesticide Detection**

Abstract

AbstractIn this work, a novel approach is adopted to synthesize graphene oxide (GO) and reduced graphene oxide (rGO) from a natural precursor Desmostachya bipinnata (halfa grass). GO is synthesized by treating ash of halfa grass with aqueous and molten KOH. Further, reduced with lemon extract to synthesize rGO. Then GO and rGO active SERS substrates are fabricated with flexible adhesive tape. Structural and morphological features of SERS substrates are analyzed. Raman spectrum of GO and rGO consists of characteristic D and G peaks around 1331 and 1600 cm−1 and a 2D peak around 2700 cm−1. The variation in ID/IG ratio, decreasing inter‐planar spacing, and the redshift of UV – Vis absorption peak from 225 to 280 nm confirm the reduction of GO on lemon extract treatment. SERS activity of fabricated substrates is analyzed with agro pesticide thiabendazole (TBZ). The detection range of TBZ by SERS substrate lies between 1 mM to 1 nM with a minimum detection limit of 1 nM. This study emphasizes the use of GO synthesized from aqueous KOH treatment and reduced with lemon extract (rGO) for the development of highly sensitive, low cost and flexible SERS substrates to detect TBZ in various agricultural products.