Modification of carbon paste electrode with Ni-clinoptilolite nanoparticles for electrocatalytic oxidation of methanol

Abstract

In this work, clinoptilolite nanoparticles (NClin) and Ni(II)-exchanged NClin (Ni(II)-NClin) were characterized by XRD and TEM techniques. The exchanged zeolite was used for the modification of carbon paste electrode (Ni(II)-NClin/CPE). The obtained modified electrode was then used for studding the electrocatalytic oxidation of methanol in alkaline solution by cyclic voltammetry and chronoamperometry techniques. The effects of some key operating parameters such as: zeolite particle size, nature and concentration of the supporting electrolytes, pH of solution, electrode ingredients and potential scan rate on the voltammetric behavior of the modified electrode were studied. The modified electrode significantly decreased (520mV) the overvoltage of the oxidation of methanol with respect to unmodified carbon paste electrode. Apparent charge transfer rate constant and transfer coefficients for the modified electrode were respectively obtained as: ks=0.053s−1, αc=0.51 and αa=0.44 in the absence of methanol and αa=0.66 in the presence of methanol. The catalytic rate constant for the oxidation of methanol by the proposed electrocatalyst was also estimated about 331M−1s−1 by chronoamperometry.