Bio-inspired AgNPs, multilayers-reduced graphene oxide and graphite nanocomposite for electrochemical H2O2 sensing

Abstract

A bio-mediated route for the synthesis of silver nanoparticles (AgNPs) is an area of interest in research of many scientists, and this work aims to study the electrocatalytic activity of these particles during electrochemical sensing of H2O2 in a phosphate buffer media. The composite electrodes were fabricated using nearly spherical AgNPs and reduced graphene oxide (rGO) with the graphite (99.999% purity) support made of graphite paste. Graphene oxide (GO) was first synthesized using the modified Hummers method followed by rGO synthesis by chemical reduction of GO. rGO is consisting of about nine layers of rGO sheets of a wrinkled surface morphology with an intensity ratio of D to G band (ID/IG) of 1.17 and an interplanar d-spacing of 0.36 nm as evidenced by HRTEM micrograph. There was about 10 times increase in the cell current with the AgNPs-impregnated composite-electrode compared to without AgNPs impregnation, and an overpotential of H2O2 reduction was found to be -1.373 V with a detection limit of 19.04µM and 95.3% electrode stability with the graphite-rGO-AgNPs composite electrode. A nafion membrane cast on the rGO-AgNPs prevented the leakage of this composite from the electrode surface. The interference of various electroactive compounds on the amperometric response of the graphite-rGO-AgNPs electrode was also investigated.