Construction of Cu2O-g-C3N4/MoS2 composite material through the decoration of Cu2O nanoparticles onto the surface of two-dimensional g-C3N4/MoS2 heterostructure for their application in electrochemical hydrogen evolution

•A novel Cu2O-g-C3N4/MoS2 composite material was synthesized.•The composite material demonstrated excellent catalytic performances in hydrogen evolution reaction in acidic media.•The composite exhibited a low onset potential of −0.14 V vs RHE and a high current density of 237.6 mA/cm2 at −0.8 V.•The composite displayed excellent durability as a catalyst in HER with no drop in the current density for many hours.•Reaction kinetics and mechanism were explained with the help of the Tafel slope.