Elimination Voltammetry with Linear Scan (ELSV) Study of Methanol Electro-Oxidation on Galvanostatically Deposited Ni

Abstract

Elimination voltammetry with linear scan (EVLS) is an analysis method that allows the decomposition of the measured current into its capacitive, diffusional, and kinetic contributions. This method was applied to study the electro-oxidation of methanol on nickel films deposited galvanostatically on gold. This analysis suggests a strong dependence of the NiOOH formation and methanol oxidation on the scan rate. According to the EVLS deconvolution, at high scan rates (> 100 mV s−1), the oxidation of Ni(OH)2 to NiOOH has a remarkable resemblance to a reaction that proceeds in an adsorbed state. Decreasing the scan rate results in qualitative changes of the particular currents, implying the occurrence of electrochemical processes that require a larger time scale (>0.5 s), like the formation of the water intercalated γ-NiOOH. For the methanol electro-oxidation process, the main contribution comes from the kinetic current; however, increasing the scan rate reveals a parallel diffusional process related to the oxygen evolution.