MoS₂ Nanoflowers Grown on Plasma-Induced W-Anchored Graphene for Efficient and Stable H₂ Production Through Seawater Electrolysis

Herein, it is found that 3D transition metal dichalcogenide (TMD)—MoS₂ nanoflowers—grown on 2D tungsten oxide-anchored graphene nanosheets (MoS₂@W-G) functions as a superior catalyst for the hydrogen evolution reaction (HER) under both acidic and alkaline conditions. The optimized weight ratio of MoS₂@W-G (MoS₂:W-G/1.5:1) in 0.5 M H₂SO₄ achieves a low overpotential of 78 mV at 10 mA cm^–2, a small Tafel slope of 48 mV dec^–1, and a high exchange current density (0.321 mA cm⁻²). Furthermore, the same MoS₂@W-G composite exhibits stable HER performance when using real seawater, with Faradaic efficiencies of 96 and 94% in acidic and alkaline media, respectively. Density functional theory calculations based on the hybrid MoS₂@W-G structure model confirm that suitable hybridization of 3D MoS₂ and 2D W-G nanosheets can lower the hydrogen adsorption: Gibbs free energy (∆G_H*) from 1.89 eV for MoS₂ to –0.13 eV for the MoS₂@W-G composite. The excellent HER activity of the 3D/2D hybridized MoS₂@W-G composite arises from abundance of active heterostructure interfaces, optimizing the electrical configuration, thereby accelerating the adsorption and dissociation of H₂O. These findings suggest a new approach for the rational development of alternative 3D/2D TMD/graphene electrocatalysts for HER applications using seawater.