Modification of a glassy carbon electrode with gold–platinum core–shell nanoparticles by electroless deposition and their electrocatalytic activity

Abstract

Gold–platinum (Au@Pt) nanoparticles with a core–shell structure were fabricated on a glassy carbon electrode (GCE) by an electroless deposition method. Initially, gold nanoparticles (AuNPs) were deposited on GCE by reducing HAuCl₄ with NH₂OH. SEM studies showed that the size of the deposited AuNPs was found to be 30 nm. The deposited AuNPs on GCE act as the nucleation centre for the deposition of platinum nanoparticles (PtNPs) in the presence of H₂PtCl₆ and NH₂OH. The size of the PtNP increases on increasing the electroless deposition time. The SEM studies demonstrated that the electroless deposition of Pt on Au was isotropic and uniform. Further, Au@Pt modified substrates were characterized by X-ray photoelectron spectroscopy (XPS), an X-ray diffraction method (XRD), energy dispersive X-ray analysis (EDAX) and cyclic voltammetry (CV). XPS showed characteristic binding energies at 71.2 and 74.4 eV for PtNPs and 83.6 and 87.3 eV for AuNPs indicating the zero valent nature of both Au and Pt. Further, the electrocatalytic activity of the Au@Pt modified electrode was examined by studying the reduction of dioxygen and oxidation of hydrazine. The modified electrode showed higher electrocatalytic activity towards the oxidation of hydrazine not only by shifting its oxidation potential towards a less positive potential but also enhancing the oxidation peak current. It also exhibited higher electrocatalytic activity towards the reduction of dioxygen by shifting its reduction overpotential by 650 mV towards a less positive potential when compared to bare GCE.