Synthesis and characterization of Nanozyme-supported Reduced Graphene Oxide/Chitosan/Ag as an enzyme-like catalyst for Carbaryl Pesticide Detection

Abstract This study presents the synthesis and characterization of rGO/CS/Ag nanozyme, an artificial enzyme with peroxidase-like activity. A complex nanozyme of reduced graphene oxide (rGO), silver (Ag), and chitosan (CS) as a catalyst material and a synthetic enzyme for the detection of carbaryl pesticide is reported in this study for the first time. FTIR analysis confirmed the reduction of graphene oxide (GO) to reduced graphene oxide (rGO) using urea, removing oxygen-containing functional groups, but still leaving some oxygen groups. XRD analysis showed a reduction in the interlayer spacing of rGO after reduction, with the nanozyme displaying a uniform distribution of Ag on the rGO surface. SEM and BET analysis revealed a mesoporous structure in the rGO/CS/Ag nanozyme, with a large surface area suitable for catalytic applications. The catalytic activity was tested using a TMB-H₂O₂ system, and the results showed good peroxidase activity, with the nanozyme showing a high affinity for the TMB substrate. Furthermore, inhibition studies using the pesticide carbaryl confirmed that the nanozyme operates through a non-competitive inhibition mechanism. Carbaryl detection was successfully achieved with a low detection limit (0.0036 mM), demonstrating the potential of this nanozyme for environmental monitoring and sensor applications. This study highlights the promising catalytic and detection capabilities of the rGO/CS/Ag nanozyme in various applications, including catalysis and sensing.