Nonenzymatic Sensing of Hydrogen Peroxide Using a Glassy Carbon Electrode Modified with Graphene Oxide, a Polyamidoamine Dendrimer, and with Polyaniline Deposited by the Fenton Reaction

A highly sensitive electrochemical sensor is described for the determination of H2O2. It is based on based on the use of polyaniline that was generated in-situ and within 1 min on a glassy carbon electrode (GCE) with the aid of the Fe(II)/H2O2 system. Initially, a 2-dimensional composite was prepared from graphene oxide and polyamidoamine dendrimer through covalent interaction. It was employed as a carrier for Fe(II) ions. Then, the nanocomposite was drop-coated onto the surface of the GCE. When exposed to H2O2, the Fe(II) on the GCE is converted to Fe(III), and free hydroxy radicals are formed. The Fe(III) ions and the hydroxy radicals catalyze the oxidation of aniline to produce electroactive polyaniline on the GCE. The resulting sensor, best operated at a working potential as low as 50 mV (vs. SCE) which excludes interference by dissolved oxygen, has a linear response in the 500 nM to 2 mM H2O2 concentration range, and the detection limit is 180 nM. The sensor was successfully applied to the determination of H2O2 in spiked milk and fetal bovine serum samples.