Design of XS₂ (X = W or Mo)-Decorated VS₂ Hybrid Nano-Architectures with Abundant Active Edge Sites for High-Rate Asymmetric Supercapacitors and Hydrogen Evolution Reactions

Two-dimensional layered transition metal dichalcogenides have emerged as promising materials for supercapacitors and hydrogen evolution reaction (HER) applications. Herein, the molybdenum sulfide (MoS₂)@vanadium sulfide (VS₂) and tungsten sulfide (WS₂)@VS₂ hybrid nano-architectures prepared via a facile one-step hydrothermal approach is reported. Hierarchical hybrids lead to rich exposed active edge sites, tuned porous nanopetals-decorated morphologies, and high intrinsic activity owing to the strong interfacial interaction between the two materials. Fabricated supercapacitors using MoS₂@VS₂ and WS₂@VS₂ electrodes exhibit high specific capacitances of 513 and 615 F g⁻¹, respectively, at an applied current of 2.5 A g⁻¹ by the three-electrode configuration. The asymmetric device fabricated using WS₂@VS₂ electrode exhibits a high specific capacitance of 222 F g⁻¹ at an applied current of 2.5 A g⁻¹ with the specific energy of 52 Wh kg⁻¹ at a specific power of 1 kW kg⁻¹. For HER, the WS₂@VS₂ catalyst shows noble characteristics with an overpotential of 56 mV to yield 10 mA cm⁻², a Tafel slope of 39 mV dec⁻¹, and an exchange current density of 1.73 mA cm⁻². In addition, density functional theory calculations are used to evaluate the durable heterostructure formation and adsorption of hydrogen atom on the various accessible sites of MoS₂@VS₂ and WS₂@VS₂ heterostructures.