Silver nanoparticles and polyvinylpyrrolidone-graphene quantum dots comodified glassy carbon electrode for amperometric sensing of hydrogen peroxide

Graphene quantum dots (GQDs), graphene sheets with lateral sizes of less than 100 nm, are materials with characteristics derived from both graphene and carbon dots [1]. Due to their novel properties,such as fascinating optical, electronic and biocompatibility, sensors based on GQDs can achieve 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 electroactive analytes[2]. Silver nanoparticles not only have characteristics in common with noble metal nanoparticles, but also have unique properties such as the capacitance character, good electrical conductivity and high catalytic activity. Silver has the highest electrical conductivity among all metals and Ag nanostructures are considered to be instable. Moreover, Ag nanoparticles would be an ideal conductor to form electron transferring channels between the target molecules and the electrode surface [3]. In this study, Ag nanoparticles and wrapped graphene quantum dots with polyvinylpyrrolidone were used to modify the surface of a glassy carbon electrode for the detection of hydrogen peroxide. The electrocatalytic activity of the film was investigated by cyclic voltammetry and amperometric techniques for developing an electrochemical sensor. The synergist cooperation between Ag nanoparticles and graphene quantum dots could increase specific surface area and enhance electronic and catalytic properties of glassy carbon electrode. The response to H2O2 at a working potential of −0.3 V (vs. Ag/AgCl) was linear in 200 μM to 9 mM concentration range at pH 7.2. The detection limit of hydrogen peroxide was 52.3 μM, demonstrating the superior detection efficiency of the Ag nanoparticles and graphene quantum dots co-modified glassy carbon electrode as a new sensing platform.