An Efficient Amperometric Sensor for Hydrogen Peroxide by Using a Carbon Paste Electrode Modified with Cobalt Impregnated Zeolite

Cobalt impregnated zeolite-modified electrode was prepared by mixing cobalt-zeolite (Co-Z) and graphite powder with different percentages. Using the cyclic voltammetric technique, the electrochemical oxidation of hydrogen peroxide at such electrodes was investigated. Experiments on zeolite show that it is not electrochemically active towards hydrogen peroxide oxidation in NaOH solution. The presence of cobalt ions in the zeolite matrix, by soaking the electrode in an aqueous Co(NO3)2 solution, markedly enhances the electrocatalytic activity which was found to depend on the cobalt content. On the other hand, the presence of zeolite and/or Co metals in the catalyst is essential; however, the electro-catalytic activity depends on different percentages of Co-Z. Under the selected conditions, the anodic peak current was linearly dependent on the concentration of the hydrogen peroxide in the range 0.03-9 and 0.006-0.1 mM with CV and amperometric methods, respectively. The detection limits (S/N=3) were also estimated to be 17 and 2.5 μM.