Elaboration of new electrodes with carbon paste containing polystyrene functionalized by pentadentate nickel(II)-Schiff base complex - Application to the electrooxidation reaction of methanol and its aliphatic analogs.

Polystyrene functionalized by a Schiff base ligand as N,N'-bis(salicylidenepropylene triamine)-N-para-aminomethylpolystyrene was synthesized from poly(4-chloromethylstyrene) and Schiff base ligand N, N'-bisalicylidenepropylenetriamine. Coordinated with nickel ion, this polystyrene Schiff base gives the expected nickel complex. The modified electrodes obtained from graphite paste and nickel complex covalently grafted onto the polystyrene were prepared in a ratio 70: 30 wt%. Its voltammogram, recorded in alkaline solution, showed a well-defined redox process corresponding to Ni(II)/Ni(III) redox couple. This modified graphite paste electrode showed a good stability. The electrocatalytic activity of the oxidation reaction of some aliphatic alcohols has been studied by cyclic voltammetry with various concentrations and different scan rates. Thus, these electrodes revealed good electrocatalytic activity towards methanol, ethanol and isopropanol alcohols showing that the oxidation current peak increases linearly with alcohol concentration. However, the electrocatalytic current decreases with the increase of the length of the aliphatic chain as expressed by the following sequence: i(cata) (methanol) > i(cata) (ethanol) > i(cata) (isopropanol). (C) 2015 Published by Elsevier Ltd.