High Electrocatalytic Behaviour of Ni Impregnated Conducting Polymer Coated Platinum and Graphite Electrodes for Electrooxidation of Methanol

Abstract

In this work nickel modified polymer composites have been synthesized electrochemically for methanol electrooxidation on platinum and graphite electrodes. Ni (II) ions were incorporated on polyaniline and poly (o-aminophenol)(PANI/POAP) bilayer structure from 0.1M Nickel sulphate hexahydrate solution at open circuit potential (OCP).TheNi (II) deposited composites were characterized with Fourier Transform Infrared (FTIR) spectroscopy, Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Cyclic voltammetry characterization exhibits stable redox pair of Ni+3/Ni+2 for both electrodes. Fourier transform infrared spectroscopy was used for functional group analysis. Ni (II) peaks were observed in the region of 400–700cm−1 along with peaks at 1102cm−1 and 1400–1600cm−1 for polyaniline and phenoxazine units. The Ni-polymer composite on platinum and graphite electrode followed different phenomenon for methanol electroxidation in alkaline media. The cyclic voltammetry results showed significantly large methanol oxidation on platinum substrate with charge storage capacity of 196μ F/cm2 for 1.5M methanol in alkaline media as compared to 8.306μF/cm2 of graphite. The diffusion controlled linear response for increase rate of methanol concentration has been obtained for Ni (II)/PANI/POAP-Pt. The electrochemical impedance spectroscopy (EIS)results indicated increase in charge storage capacity from 10−4F/cm2 to 10−3F/cm2 with increasing potentials at lower frequency region.The phase shift was observed from 60–40degrees for increased potentials at low frequency range in EIS analysis. The increased conductive behavior from 10−5 to 10−2s/cm2 has been obtained fornickel modified polymer composite at higher frequency region in EIS analysis.