2D‐2D Amalgamated Heterostructured Mo _1‐x W _x S ₂ Mixed‐Metal Dichalcogenides for Supercapacitor Applications

ABSTRACT In this study, a series of mixed transition metal dichalcogenides, Mo _1‐x W _x S ₂ (x = 0.3, 0.5, and 0.7), were synthesized via a one‐pot hydrothermal method to engineer controllable 2D–2D heterostructures through a substitution strategy. The incorporation of W into the MoS ₂ lattice induces basal‐plane disorder, expanded interlayer spacing, and a high density of lattice defects in the resulting Mo _1‐x W _x S ₂ systems. XRD, Raman, and XPS analyses collectively confirm the emergence of a mixed‐metallic 1T/2H phase and distortion in the S‐Mo/W‐S stacking, validating the formation of a hetero‐layered 2D–2D architecture across all compositions. Electron microscopy reveals a clear transition from aggregated MoS ₂ nanopetals to an increasingly intertwined and interconnected 2D‐sheet‐like network, with the Mo _0.5 W _0.5 S ₂ composition exhibiting the most optimized heterolayer‐assembly and enhanced surface area. Benefiting from this engineered 2D–2D framework, Mo _0.5 W _0.5 S ₂ delivers a high specific capacitance of 559 F g ⁻¹ at 1 A g ⁻¹ , nearly double that of pristine‐MoS ₂ . A symmetric‐supercapacitor device fabricated using this optimized electrode achieves an energy density of 24.1 Wh kg ⁻¹ at a power density of 866.6 W kg ⁻¹ and retains 88.4% capacitance with 100% coulombic efficiency after 10,000 cycles. These features collectively enable fast ion‐transport in the system, thereby enhancing the electrochemical performance of the developed supercapacitor device.