V 2 O 5 Interfacial Passivation with 2H–MoSe 2 Nanostructures for Ion Intercalation and Diffusion-Driven Charge Storage in Symmetric Supercapacitors

Here, varying amounts of V 2 O 5 nanobelts (0.5%, 1%, 3%, 5%, and 7%) were incorporated into 2H–MoSe 2 nanoflowers to construct binary heterostructures via a hydrothermal approach, targeting improved electrochemical charge-storage behavior by enhancing ion-intercalation processes. The crystallographic features, such as crystallinity, phase structure, and interplanar spacing, were analyzed using X-ray diffraction (XRD) to exhibit enhanced d-spacing and dislocation density of heterostructures. Field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) reveal the enhancement of surface area and porosity with nanostructured features. In addition, the evidence of elemental composition, along with defect mediation, was confirmed via X-ray photoelectron spectroscopy (XPS). Within the three-electrode system, the electrochemical analysis reveals diffusion-driven charge storage ( b ≈ 0.5), consistent with the plateau-like GCD features, indicating intercalation-assisted Faradaic charge storage. Among the series, the 1% V 2 O 5 -incorporated MoSe 2 heterostructure offers the most effective balance of redox activity and charge/ion transport, resulting in the highest capacitance of 948.13 F/g at 0.33 A/g and retaining 80.17% of its capacitance after 12,000 cycles. The improved electrochemical performance is attributed to increased interlayer spacing and disorder-induced surface sites, which facilitate efficient ion adsorption, intercalation, and surface redox reactions. Furthermore, the lower interfacial charge transfer resistance may boost the specific capacitance by aiding the faradaic process. In a symmetric two-electrode setup, the 1% heterostructure showed a specific capacitance of 236.5 F/g at 0.33 A/g and achieved an energy density of 21.02 Wh/kg at a power density of 4000 W/kg. Finally, a prototype supercapacitor was fabricated with the optimized MoSe 2 /V 2 O 5 (1%) nanocomposite as the electrode in a coin cell setup to illuminate LEDs. The findings of this study demonstrate that the incorporation of V 2 O 5 into MoSe 2 provides an enhanced ion intercalation rate, featuring excellent charge storage capacity, elevated energy density, and remarkable long-term stability, and is a promising and dependable electrode material for high-performance symmetric hybrid supercapacitors, highlighting its potential for advanced energy storage technologies.