A graphite sheet modified with reduced graphene oxide-hyper-branched gold nanostructure as a highly efficient electrocatalyst for hydrogen evolution reaction

Abstract

Hydrogen is considered as the most important energy carrier for the future. Water electrolysis is a green method for hydrogen production and simple technology that produces very clean gases. However, the main problems with this method are that this process possesses slow kinetic, consumes many energies and its common electrocatalyst is platinum (Pt) based which is an expensive and rare substance. The use of accessible electrocatalyst materials with new shape or structure, which can reduce the overpotential for the hydrogen evolution reaction (HER) is one of the ways to increase the efficiency of the electrolyzers. Herein, first, a graphite sheet was modified with graphene oxide (GO) and then a hyperbranched structure of gold was electrodeposited on it by controlling the electrodeposition conditions. The electrode surface was characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR). The HER performance of the prepared electrodes was evaluated using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) methods in 0.5 M H2SO4 solution. The as-prepared electrode revealed outstanding HER performance with a near-zero onset overpotential (4.7 mV), overpotential of 44 mV at 10 mA cm−2, a high current density of 127.9 mA cm−2 at 200 mV and also satisfactory stability. Such results suggest that this electrocatalyst is promising for generating clean energy on an industrial scale.