Interfacial infrared reflection spectroscopic evidence for potential-dependent electrocatalytic activity of self-assembled monolayer of nickel(II) azamacrocyclic complex toward hydrogen peroxide oxidation

Self-assembled monolayers (SAM) and mixed monolayers of a redox-active nick el(LI) azamacrocyclic complex 1 show an efficient electrocatalytic activity toward the oxidation of H2O2. The cyclic voltammograms recorded at station ary and rotating disk electrodes for the electrocatalytic oxidation of H2O2 exhibit unique sharp anodic peaks of inverted "V" shape in both anodic and cathodic scans, largely depending on the concentration of the supporting e lectrolyte NO3- anion. The electrocatalytic oxidation of H2O2 is found to p roceed via an inner-sphere electron-transfer mechanism. The local concentra tion of NO3- anions at the monolayer-solution interface is investigated in situ as a function of applied potential by subtractively normalized interfa cial infrared reflection spectroscopy. The potential-dependent increase in the local concentration of NO3- anion at the interface, which could lead to the stabilization of the intermediates involved in the electrocatalytic ox idation of H2O2, has been speculated as the cause for the unique cyclic vol tammetric behavior observed in the electrocatalytic oxidation of H2O2.