Synthesis of rGO–Nps hybrids with electrocatalytic activity for hydrogen evolution reaction

Abstract

A hybrid nanomaterial with palladium nanoparticles (PdNps) supported on reduced graphene oxide (rGO) flakes, dispersed in an aqueous solution was synthesized through a reproducible and scalable electrochemical method. The rGO–PdNps hybrid with excellent stability and a narrow range of size distribution in the aqueous dispersion is obtained. In a second step, additional plasmonic characteristics were provided by forming Au–Pd bimetallic nanostructures in the rGO flakes, through the gold nanoparticles formation by galvanic replacement on the Pd surface sites at the rGO–PdNps hybrid. The interaction of the rGO–AuPdNps with the PVP binder in aqueous dispersion was investigated by SERS (surface enhancement of Raman scattering) spectroscopy. Furthermore, both rGO–PdNps and rGO–AuPdNps hybrid nanomaterials were deposited by drop-casting on glassy carbon electrodes in order to evaluate their electrocatalytic activity for hydrogen evolution reaction (HER). Experimental findings from cyclic voltammetry in 0.5 M H2SO4 solution show that both hybrids exhibit activation of HER kinetics. Electrodes modified with rGO–AuPdNps show a current density of HER at −0.6 V vs. SCE of 9.71 mAcm−2, while that recorded for glassy carbon electrodes containing rGO was 0.18 mAcm−2 considering the geometrical area of the electrodes.