Hetero-epitaxial grown Pt@Au core-shell bimetallic nanoparticles on reduced graphene oxide (RGO) as electrocatalyst for oxygen reduction reaction in alkaline media

Abstract

The core-shell structured Pt@Aubimetallic nanoparticles (NPs) were decorated on the reduced graphene oxide (RGO) surface by a heteroepitaxial growth method. The morphological details of Pt@Au/RGO core/shell bimetallic NPs were assessed by high-resolution transmission electron microscopy (HR-TEM), x-ray diffraction (XRD), and energy-dispersive x-ray spectroscopy (EDS). Electron microscopy results revealed that Pt@Au particles of 3.4 nm were firmly attached to RGO sheets. The electrochemical response of Pt@Au/RGO nanostructured electrocatalyst was measured through cyclic voltammetry (CV) at room temperature in 0.1 M KOH solution. Oxygen reduction reaction (ORR) efficacies of Pt@Au/RGO were evaluated by linear sweep voltammetry (LSV) by rotating catalyst-coated glassy carbon (GC) electrode at different rotation speeds in oxygen saturated 0.1 M KOH solution. The electrochemical activity descriptors (half-wave potential, onset potential, limiting current density) were assessed from ORR polarisation curves. The results revealed that Pt@Au/RGO bimetallic NPs showed enhanced higher catalytic activity towards ORR compared to commercial Pt/C catalyst as well as similarly synthesised Pt/RGO and Au/RGO. The enhanced catalytic activity of Pt@Au/RGO electrocatalyst might result from the core/shell structure with a tiny Pt core and a thin Au shell, as well as the synergistic effects of Au and Pt.