Composites of graphene-Mo₂C rods: highly active and stable electrocatalyst for hydrogen evolution reaction

Abstract

Mo based compounds are being explored as an alternative for Pt in hydrogen evolution reactions. Reduced graphene oxide (rGO) based Mo₂C composites have been synthesized in two step reaction i.e. complexation followed by carbonization in presence of rGO. The composites were characterized using PXRD, electron microscopy, XPS and Raman spectroscopy. The excellent electrocatalytic performance in water splitting using these composites was reflected from the high catalytic current density of ∼125 mA-cm^-2 (@ 400 mV vs. RHE and stability of the rGO based composite in long run hydrogen evolution reactions ( > 15 hrs chrono studies and >1200 LSV cycles) in acidic medium. The role of graphene in the composite is critical for its electrocatalytic efficiency and very high catalytic activity is possible with low onset potential (59 mV) following Volmer-Heyrovsky reaction mechanism. Kinetics of the hydrogen evolution on the composite surface has been studied using charge transfer resistance, Bode phase angles and Tafel slopes.