Low Potential and Non-Enzymatic Hydrogen Peroxide Sensor Based on Copper Oxide Nanoparticle on Activated Pencil Graphite Electrode

An electrochemical sensor for H2O2 determination was prepared by electrodepositing copper oxide nanoparticles on the activated pencil graphite electrodes. At first, a study has been made of the optimum conditions for chemical activation of the pencil graphite electrodes (APGE) and then the activated pencil graphite electrode was modified with copper oxide nanoparticles (CuO/APGE) and used as a non-enzymatic hydrogen peroxide sensor. The morphology of the modified electrode surface was investigated by scanning electron microscopy (SEM). Upon the addition of H2O2, the modified electrode (CuO/APGE) exhibits significant oxidation of H2O2 with starting potential around + 0.05 V (vs. Ag/AgCl) which dramatically decreases the overpotential of H2O2 oxidation. Under the optimal experiment conditions, the electrocatalytic response current of this sensor was proportional to the H2O2 concentration in the range of 5.0 x 10(-6) to 1.6 x 10(-3) mol L-1 with a detection limit down to 0.21 mu mol L-1 (signal/noise = 3). The sensitivity was calculated to be 4.75 mu AL mmol(-1). The electrochemical active surface area and the catalytic rate constant of hydrogen peroxide electro- oxidation were calculated. The H2O2 sensor exhibited a low detection limit, a good signal reproducibility (relative standard deviation (RSD), n = 4) 2.36% and the accurate measurements in milk as the real sample.