Electrocatalytic Behavior of Nano Zeolite Modified Carbon Paste Electrode for Oxidation of Hydrazine

liquid fuels such as hydrazine, alcohols, alkaline borohydride and hydrazine solutions have been used in the direct liquid fuel cells [1]. several companies have started to supply power sources based on fuel cell technology to the market. The potential applications of fuel cells are broad, from mobile devices to automobiles and space ships. At present, one of the main focus of fuel cell research is portable devices, such as mobile phones, mp3 players and notebooks [2,3]. Hydrazine is commonly used in some industrial applications such as catalyst, corrosion inhibitor , reducing agent,antioxidant, emulsifier starting material in the production of some insecticides and herbicides, pesticides, dye stuffs, explosive, and the preparation of several pharmaceutical derivatives [4]. In the case of oxidation of hydrazine using electrochemical procedures, unfortunately, ordinary carbon electrodes have a number of limitations for electrochemical detection of hydrazine, such as low sensitivity and reproducibility, high overpotential for oxidation, low stability, and slow electron transfer [5]. Therefore, a main attention has been focused on the development of materials capable of the catalytic electrooxidation of hydrazine. Recently, many groups introduced several compounds to improve the anodic oxidation of hydrazine. Zeolitemodified electrodes have been developed for the determination of various compounds and the use of a mixture of a zeolite and graphite powder in various forms has been projected. Zeolitesupported electrocatalysts can be subjected to improve the performance of the Electrocatalytic responses with reduced over potentials and increased voltammetric/amperometric signals allowing low detection limits and high sensitivities. This paper intends to introduce a novel zeolite modified carbon paste electrode based on Ni modified synthesized nano ZSM-5 crystallites for the electrocatalytic oxidation of ethanol. The rate constant of the oxidation process is calculated using chronoamprometric studies.The used nano ZSM-5 zeolite was synthesized as literature [6]. All other used chemicals were purchese from Merc. The electrochemical experiments were performed on a potentiostat/galvanostat (sama 500-c Electrochemical Analysis system, sama, Iran). SCE was 56 used as the reference electrode, a platinum wire as the auxiliary electrode, and a home-made carbon paste electrode (ca. 3.4 mm internal diameters) as the working electrode. Appropariated ammount of synthesized nano zeolite was lightly ground and immersed to 10 ml 1 M NiCl2 solution for 1 h. Then the solid was dried. The 30% (W/W) Ni2+-zeolite to graphite powder paste was made by mixing the given quantity of Ni2+-zeolite and graphite powder in diethyl ether and the solvent was evaporated by stirring a mixture. Then paraffin was blended by hand mixing and the resulting paste was inserted in the bottom of a glass tube. The electrical connection was implemented by a copper wire fitted into the opposite opening of the glass tube. For the comparission the unmodified carbon paste was prepared. Obtained results show that proposed modified carbon paste electrode can used for electrocatalytic oxidation of hydrazine as a fuel for fuel cell and the catalytic rate constant for this process was calculated as 9.6*103 M-1 s-1 (Fig 1). Figure1, Cyclic voltamograms for (a) Ni/Zeolite/CPE, (b) CPE in the absent and (c) Ni/Zeolite/CPE, (d) CPE in the presence of 0.11M hydrazine in the 0.1M NaOH at scan rate 20mVs-1 .