Morteza Akhond - Professor Massoumi Laboratory, Department of Chemistry, Faculty of Sciences, Shiraz University
Hamed Tavakkoli - Professor Massoumi Laboratory, Department of Chemistry, Faculty of Sciences, Shiraz University,
Ghodratollah Absalan - Professor Massoumi Laboratory, Department of Chemistry, Faculty of Sciences, Shiraz University,

Graphene quantum dots (GQDs), graphene sheets with lateral sizes of less than 100 nm, arematerials with characteristics derived from both graphene and carbon dots [1]. Due to their novelproperties,such as fascinating optical, electronic and biocompatibility, sensors based on GQDs canachieve a high level of performance. Furthermore, GQDs increase contact area with the analyte,which could increase the electrochemical active surface area to interact with some electroactiveanalytes[2]. Silver nanoparticles not only have characteristics in common with noble metalnanoparticles, but also have unique properties such as the capacitance character, good electricalconductivity and high catalytic activity. Silver has the highest electrical conductivity among allmetals and Ag nanostructures are considered to be instable. Moreover, Ag nanoparticles would bean ideal conductor to form electron transferring channels between the target molecules and theelectrode surface [3]. In this study, Ag nanoparticles and wrapped graphene quantum dots withpolyvinylpyrrolidone were used to modify the surface of a glassy carbon electrode for the detectionof hydrogen peroxide. The electrocatalytic activity of the film was investigated by cyclicvoltammetry and amperometric techniques for developing an electrochemical sensor. The synergistcooperation between Ag nanoparticles and graphene quantum dots could increase specific surfacearea and enhance electronic and catalytic properties of glassy carbon electrode. The response toH2O2 at a working potential of −0.3 V (vs. Ag/AgCl) was linear in 200 μM to 9 mM concentrationrange at pH 7.2. The detection limit of hydrogen peroxide was 52.3 μM, demonstrating the superiordetection efficiency of the Ag nanoparticles and graphene quantum dots co-modified glassy carbonelectrode as a new sensing platform.

Silver nanoparticles, Graphene quantum dots, Polyvinylpyrrolidone, Hydrogenperoxide, Amperometric sensing