N-doped Graphene/ZnFe2O4: A novel nanocomposite for intrinsic peroxidase based sensing of H2O2

Abstract A novel nitrogen–doped graphene/ZnFe2O4 nanocomposite for intrinsic peroxidase based catalytic sensing of H2O2 was synthesized via facile hydrothermal process. The morphology and structural characteristics were analyzed through FESEM, XRD, Raman and XPS analysis. CHN analysis was carried out to confirm the doping percentage of nitrogen on graphene sheet which is consistent with the stoichiometry used for the synthesis. Peroxidase activity of the optimized novel nanocomposite with 3,3′,5,5′- tetramethylbenzidine (TMB) as a substrate shows high efficiency due to the presence of n-type nitrogen dopants on the graphene sheet. The catalytic oxidation of TMB and reduction of H2O2 occurs simultaneously which could be examined using UV–vis spectroscopic analysis. The intensity of absorption peak at 652 nm increases linearly with the concentrations of TMB as well as H2O2. The sensing activity goes upto 0.25 mM concentration for TMB and 0.025 mM for H2O2 and the Michaelis-Menten constant and the rate of the reaction was found to be 115.52/mM and 7.44 × 10−8/Ms−1 respectively from the Lineweaver- Burk plot.