Electrodeposited gold nanostructures at Nafion–poly(o-phenylenediamine) modified electrode and its electrocatalytic application

Abstract

A facile method to prepare gold (Au) nanostructures at the Nafion–poly(o-phenylenediamine) (Nf–PPD) composite film modified electrode (ITO or GC/Nf–PPD/Au) and its application toward the electrocatalytic reduction of oxygen in acidic medium are reported. The formation of Au nanostructures at the Nf–PPD composite film modified electrode was monitored by in-situ spectroelectrochemical method. The oPD monomer was oxidatively polymerized during the electrodeposition of Au nanostructures. The Nf–PPD/Au modified electrode was characterized by cyclic voltammetry, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The composite film formed on the electrode surface was dissolved in ethanol and the Au nanostructures were characterized by high resolution transmission electron microscopy (HRTEM) analysis. The HRTEM images showed the formation of ginger shaped Au nanostructures by a fusion growth process at the Nf–PPD film. The GC/Nf–PPD/Au modified electrode displayed a better electrocatalytic activity in terms of peak current density, mass activity and stability toward oxygen reduction reaction (ORR) in acidic medium than the other controlled modified electrodes investigated in this work. The presence of PPD and Au nanostructures in the Nf matrix at the modified electrode showed a synergistic catalytic activity in the ORR.