Elaboration of carbon paste electrode containing pentadentate Nickel-(II) Schiff base complex: Application to electrochemical oxidation of thiosulfate in alkaline medium
Walid Belbacha, Farid Nâamoune, Hamza Bezzi, Nora Hellal, L. Zerroual, Kahoul Abdelkarim, Bouzarafa brahim, Marta Fernández‐García, Daniel López
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 NiIII/NiII 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−1. The electrogenerated NiIII species on the surface of the electrode act as an excellent catalyst toward thiosulfate oxidation reaction with a chemical rate constant Kh equal to 23,6 M−1s−1. The different techniques involved in this study qualify our modified electrode as sensitive, reliable and very stable for thiosulfate analysis.