ELECTROCHEMICAL DETECTION OF H2O2 ON GRAPHENE NANORIBBONS/COBALT OXIDE NANORODS MODIFIED ELECTRODE

Abstract

Graphene nanoribbons (GNRs) is a narrow strip of graphene, with one-dimensional structure and possess high length-to-width ratio. GNRs was synthesized by oxidative unzipping of multi-walled carbon nanotubes (MWCNTs). The unzipping of nanotubes occurred by inducing extreme stress within the concentric walls and thus give rises to bursting or longitudinal opening of the MWCNTs. The properties of GNRs depends on width and edge orientation on its structure. The length of the GNRs were measured using HR-TEM. After that, cobalt oxide nanorods (Co₃O₄) were prepared by using hydrothermal method. The dispersion stability and catalytic activity of Co₃O₄ was enhanced by GNRs. The obtained nanocomposite (GNRs/ Co₃O₄) was characterized by UV-Visible (UV-vis) and HR-TEM images. Next, the electrochemical properties of the nanocomposite was tested against the oxidation of hydrogen peroxide (H₂O₂). H₂O₂ was one of the important marker for the reactive oxygen species (ROS) and it denatures the protein and DNA and the main contributory factor of aging. So, it is important to detect H₂O₂ in the biological, food and environmental samples. The obtained GNR/Co₃O₄ was studied by using cyclic voltammetry (CV) which showed a redox peak at E^0’ of 0.932 V in phosphate buffer solution. The H₂O₂ electrochemical oxidation was performed on a GNR/Co₃O₄ modified electrode. The electrochemical studies revealed that the H₂O₂ oxidation occurred at 0.76 V. A linear response was obtained for H₂O₂ concentration from 0.1 – 2 μM and the limit of detection (LOD) was calculated to be 0.089 µM. The selectivity of the sensor was also studied for H₂O₂ oxidation with other biomolecules associated with the human body and the results showed that interfering effect is negligible. It was suggested that the GNR/Co₃O₄ modified electrode can be used for selective detection of H₂O₂ in various samples.