Elaboration of carbon paste electrode containing pentadentate Nickel-(II) Schiff base complex: Application to electrochemical oxidation of thiosulfate in alkaline medium

Abstract

A Nickel Schiff base complex, insoluble in water, was synthesized and used as modifier. A Nickel Schiff base modified carbon paste electrode MCPE was build. The electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDXS), cyclic voltammetry and chronoamperometry. The modifier is elctroactive, a well defined redox couple of Ni/Ni in alkaline medium was made in evidence. It presents a quasi-reversible system with electron transfer coefficient (0.38) and electron transfer rate of 4.5 s. The electrogenerated Ni species on the surface of the electrode act as an excellent catalyst toward thiosulfate oxidation reaction with a chemical rate constant K equal to 23,6 Ms. The different techniques involved in this study qualify our modified electrode as sensitive, reliable and very stable for thiosulfate analysis.