Electrochemical Studies of Hydrogen Peroxide Oxidation on a Nanoporous Gold Surface: Fundamental and Analytical Applications

Abstract

A nanoporous gold (NPG) surface with high electroactive surface area and roughness factor was prepared via anodization-electrochemical reduction method and was used as a new platform to study the electrochemical oxidation of hydrogen peroxide (H2O2). Field-emission scanning electron microscopy (FE-SEM) analysis, cyclic voltammetry, and amperometry techniques were employed for structural morphology and electrochemical studies. The H2O2 oxidation peak potential was significantly shifted (∼0.23 V) towards a less positive direction with increased current response at the NPG surface compared to that of a bare gold electrode. The mechanism for the H2O2 anodic oxidation at the NPG surface was proposed based on the calculated transfer coefficient (α = 0.32) and the total number of electrons involved (n = 2.0) in the electrochemical process. Besides, the diffusion coefficient (D) of H2O2 in PBS solution was also calculated using the Randles-Sevcik equation (2.18 × 10−5 cm2 s−1). In addition, the analytical application of the NPG electrode was demonstrated by amperometric detection of H2O2 at a relatively less positive potential (0.57 V). The current increased proportionally to H2O2 concentration in the linear range of 0.01 to 1.8 mM and the detection limit was found to be 0.6 μM (S/N = 3).