A study of the electrochemical oxidation of hydrogen peroxide on a platinum rotating disk electrode in the presence of calcium ions using Michaelis-Menten kinetics and binding isotherm analysis

摘要

The present work demonstrates a potential suppression in the electrochemical signal of H{sub}2O{sub}2 oxidation due to the presence of Ca{sup}(2+) ions. A mechanistic scheme was proposed to include a reversible interaction of Ca{sup}(2+) ions with either the electrode surface binding sites (competitive) or the complex sites (non-competitive). The degree of inhibition was inspected by evaluating the kinetic currents as a function of [Ca{sup}(2+)] applying Koutecky-Levich kinetics. These observations were further supported with models based on enzyme kinetics such as Michaelis-Menten model applying Lineweaver-Burk plot along with non-linear least-square fitting analysis. The experimental results suggests that the strength of the complex binding sites decreases considerably with increasing [Ca{sup}(2+)] and that a single H{sub}2O{sub}2 molecule is required to combine with one available active binding site.