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

Abstract

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.