MoSx supported graphene oxides with different degree of oxidation as efficient electrocatalysts for hydrogen evolution

Abstract

A simple wet chemical method has been used to prepare MoSx in situ grown on graphene oxide (MoSx/GO) as a highly active and stable electrocatalyst for hydrogen evolution reaction (HER). The role of the oxygen-containing functional group on the surface of GO with different oxidation degrees have been studied for obtaining MoSx/GO with excellent electrochemical activity for HER. The electrochemical measurements show that MoSx/GO using the medium degree of oxidation of GO as matrix exhibits best electrocatalytic activity for HER with a small overpotential of ∼195 mV at the current density of 20 mA cm−2. A tafel slope of ∼47.7 mV per decade is obtained for MoSx/GO modified electrode. The turnover frequency per active site is calculated. Both the amount of active sites for HER and conductivity of the electrocatalyst have been greatly improved owing to the good dispersion and conductivity provided by GO matrix. Therefore, this work suggested that choosing GO with suitable oxidation degree as support is the key for synthesizing MoSx based electrocatalysts with enhanced HER activity.