Europium Molybdate/Molybdenum Disulfide Nanostructures with Efficient Electrocatalytic Activity for the Hydrogen Evolution Reaction

The design of hybrid nanostructures of molybdenum disulfide (MoS 2 ) has been extensively explored as potent electrocatalysts for hydrogen generation reactions. Here, we report the in situ synthesis of a nanocomposite containing europium molybdate [Eu 2 (MoO 4 ) 3 ] and molybdenum disulfide (MoS 2 ) for an enhanced electrochemical hydrogen evolution reaction (HER). The characteristic X-ray diffraction (XRD) peaks of both 2H–MoS 2 and α-Eu 2 (MoO 4 ) 3 confirm the formation of the nanocomposite. The nanoflower (NF) architecture of MoS 2 coupled with flakes of europium molybdate is observed in the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images, which lead to an enhanced surface area of the nanocomposite. Raman and X-ray photoelectron spectroscopy (XPS) studies reveal a variation in the layer thickness of MoS 2 and a significant interfacial electronic interaction between Eu 2 (MoO 4 ) 3 and MoS 2. As evident from the small onset potential of −0.05 V vs reversible hydrogen electrode (RHE) and a lower overpotential value of 186 mV (at a current density of 10 mA/cm 2 ), the nanocomposite outperforms pristine MoS 2 nanoflowers in terms of electrocatalytic HER. The charge-transfer resistance of the nanocomposite (80.02 Ω) is significantly low compared to pristine MoS 2 (158.37 Ω), thus confirming the enhanced interfacial charge transfer. The Tafel slope value of the nanocomposite (189 mV/dec) is notably less than that of pristine MoS 2 (313 mV/dec), indicating the enhanced HER activity of the nanocomposite. The fabrication of lanthanide-containing MoS 2 nanocomposites appears to be promising for an efficient electrocatalytic activity for the hydrogen evolution reaction.