Role of molybdenum in Ni-MoO2 catalysts supported on reduced graphene oxide for temperature dependent hydrogen evolution reaction

Non Platinum group metal (PGM) catalyst received huge attention for the electrochemical water splitting to produce hydrogen. Among different non PGM groups nickel (Ni), nickel oxide (NiO), nickel molybdenum oxide (Ni-MoOx) show very good activity towards hydrogen evolution reaction (HER). In this work, Ni and Ni-MoO2 nanostructured particles were impregnated on the reduced graphene oxide (RGO) sheets and utilized for hydrogen evolution reaction (HER) in highly alkaline medium (1 M KOH). Electrochemical studies have been done by linear sweep voltammetry (LSV) which concludes that there is decrease in overpotential of about 124 mV at 10 mA cm(-2) as we switch from Ni/RGO to Ni-MoO2/RGO. To understand reaction mechanism, temperature dependent HER have also performed within the temperature range of 293-333 K respectively. Electrochemical impedance spectroscopy (EIS), Arrhenius activation energy calculations concluded enhanced catalytic activity of Ni-MoO2/RGO. Temperature-controlled experimental data clearly confirm that addition of molybdenum leads to reduction in energy barrier for hydrogen evolution in Ni-MoO2/RGO.