1. We claim that a hierarchically integrated ternary nanocomposite comprising nickel cobalt sulfide (NiCo₂S₄), molybdenum disulfide (MoS₂), and reduced graphene oxide (rGO) is developed for electrochemical energy storage applications.

2. We claim that the NiCo₂S₄ component in the nanocomposite provides enhanced pseudocapacitive behavior through reversible redox reactions of Ni²⁺/Ni³⁺ and Co²⁺/Co³⁺.

3. We claim that the MoS₂ component contributes a two-dimensional layered structure that improves ion diffusion and increases electrochemically active surface area.

4. We claim that the reduced graphene oxide (rGO) forms a highly conductive network that enhances electron transport and reduces charge transfer resistance.

5. We claim that the ternary nanocomposite exhibits a three-dimensional interconnected porous architecture that improves electrolyte accessibility and ion transport pathways.

6. We claim that the NiCo₂S₄ is synthesized in the form of nanosheets or nanoflakes uniformly anchored onto the rGO framework.

7. We claim that MoS₂ is grown in situ over the NiCo₂S₄/rGO composite to ensure strong interfacial interaction and structural stability.

8. We claim that the synthesis of the nanocomposite involves hydrothermal or solvothermal methods followed by reduction, integration, washing, and drying processes.

9. We claim that the fabricated nanocomposite is used as an electrode material coated onto conductive substrates such as nickel foam, carbon cloth, or stainless steel.

10. We claim that the nanocomposite demonstrates high specific capacitance, superior rate capability, low internal resistance, and excellent long-term cycling stability in supercapacitor and hybrid energy storage applications.

Description:. Preamble
The rapid advancement of modern technology and the growing dependence on portable electronic devices, electric vehicles, and renewable energy systems have significantly increased the demand for efficient and reliable energy storage solutions. Conventional energy storage devices, such as batteries, though widely used, often suffer from limitations including slow charge–discharge rates, limited cycle life, and safety concerns. In this context, supercapacitors have emerged as promising alternatives due to their high power density, rapid charging capability, and excellent cycling stability. However, the relatively low energy density of supercapacitors remains a critical challenge that restricts their widespread application.
To address these limitations, there is a continuous need for the development of advanced electrode materials with enhanced electrochemical performance. Among various materials explored, transition metal sulfides have attracted considerable attention owing to their superior electrical conductivity and rich redox chemistry. In particular, nickel cobalt sulfide (NiCo₂S₄) stands out as a highly efficient pseudocapacitive material due to its multiple oxidation states, which enable reversible faradaic reactions and contribute significantly to charge storage capacity. Despite these advantages, NiCo₂S₄ alone may suffer from structural instability and limited surface accessibility during prolonged cycling.
Similarly, molybdenum disulfide (MoS₂), a two-dimensional layered material, has gained prominence for its high surface area, unique layered structure, and favorable electrochemical properties. The interlayer spacing in MoS₂ facilitates ion intercalation and diffusion, thereby improving charge storage mechanisms. However, its relatively low intrinsic electrical conductivity and tendency to restack can hinder its performance when used independently in energy storage systems.
On the other hand, reduced graphene oxide (rGO) has been widely recognized as an excellent conductive support material due to its high electrical conductivity, large surface area, and mechanical strength. rGO provides an interconnected conductive network that enhances electron transport, reduces internal resistance, and prevents aggregation of active materials. Nevertheless, rGO alone exhibits limited pseudocapacitive behavior, thereby necessitating its combination with other electrochemically active materials.
In view of the above challenges, the integration of multiple functional materials into a single hierarchical nanocomposite structure presents an effective strategy to achieve synergistic enhancement in electrochemical performance. The combination of NiCo₂S₄, MoS₂, and rGO into a ternary nanocomposite offers a balanced integration of high conductivity, abundant active sites, and structural stability. Such a composite structure can effectively overcome the individual limitations of each component while leveraging their collective advantages.
The present invention is directed towards the design and development of a hierarchically integrated NiCo₂S₄/MoS₂/rGO ternary nanocomposite, engineered to provide enhanced pseudocapacitive performance and improved charge transport characteristics. The hierarchical architecture ensures maximum exposure of electroactive sites, efficient electrolyte diffusion, and strong interfacial interactions among the constituent materials. This design significantly contributes to improved specific capacitance, rate capability, and long-term cycling stability.
Furthermore, the invention emphasizes a controlled and scalable synthesis methodology that enables uniform distribution and strong coupling of the composite components. The formation of NiCo₂S₄ nanostructures, the layered growth of MoS₂, and the incorporation of rGO into a three-dimensional conductive framework collectively result in a robust and efficient electrode material. The synthesis approach ensures reproducibility and suitability for large-scale production, making it viable for practical applications.
The developed ternary nanocomposite demonstrates superior electrochemical properties when employed as an electrode material in supercapacitors and hybrid energy storage devices. The synergistic interaction between pseudocapacitive materials and conductive carbon networks leads to enhanced energy density without compromising power density. Additionally, the structural integrity of the composite supports long-term operational stability, which is crucial for real-world applications.
4. Methodology
1. Preparation of Graphene Oxide (GO)
Initially, graphene oxide (GO) is synthesized using a modified Hummers’ method to ensure high oxidation efficiency and good dispersibility in aqueous media. Natural graphite powder is added slowly into a mixture of concentrated sulfuric acid (H₂SO₄) and phosphoric acid (H₃PO₄) under continuous stirring in an ice bath to control the exothermic reaction. Potassium permanganate (KMnO₄) is then gradually introduced as an oxidizing agent, ensuring that the temperature remains below 20°C to prevent overheating and unwanted side reactions.
The reaction mixture is subsequently heated to around 50°C and maintained for several hours to promote oxidation of graphite into graphite oxide. After completion, the reaction is quenched by adding hydrogen peroxide (H₂O₂), resulting in a color change indicating successful oxidation. The obtained product is repeatedly washed with distilled water, hydrochloric acid (HCl), and ethanol to remove residual ions and impurities. The purified GO is then dried under vacuum conditions and later dispersed ultrasonically in deionized water to obtain a stable GO suspension.

Fig. 1 Working flow of Proposed Methodology.
2. Reduction of GO to Reduced Graphene Oxide (rGO)
The prepared GO dispersion is subjected to chemical or hydrothermal reduction to convert it into reduced graphene oxide (rGO). In a typical process, a reducing agent such as hydrazine hydrate or ascorbic acid is added to the GO suspension, followed by heating at 80–100°C under continuous stirring. Alternatively, a hydrothermal reduction can be performed by transferring the GO suspension into a Teflon-lined autoclave and heating at 180°C for several hours.
During this process, oxygen-containing functional groups are removed, restoring the conjugated graphene network and significantly improving electrical conductivity. The resulting rGO is filtered, washed, and dried, forming a conductive carbon framework that will serve as the backbone of the composite.

3. Synthesis of NiCo₂S₄ Nanostructures
Nickel cobalt sulfide (NiCo₂S₄) nanostructures are synthesized via a hydrothermal or solvothermal method. Nickel salts (such as Ni(NO₃)₂·6H₂O) and cobalt salts (Co(NO₃)₂·6H₂O) are dissolved in deionized water in a molar ratio suitable for forming NiCo₂S₄. A sulfur source such as thiourea or sodium sulfide (Na₂S) is then added to the solution.
The mixture is stirred thoroughly to ensure homogeneity and then transferred into a Teflon-lined stainless steel autoclave. The reaction is carried out at temperatures ranging from 150°C to 200°C for 8–12 hours. During this process, nucleation and growth of NiCo₂S₄ occur, forming nanosheets or nanoflake-like morphologies.
After completion, the autoclave is allowed to cool naturally to room temperature. The precipitated product is collected via centrifugation, washed multiple times with deionized water and ethanol to remove unreacted precursors, and then dried in a vacuum oven. The obtained NiCo₂S₄ nanostructures exhibit high surface area and abundant redox-active sites.
4. In Situ Growth of NiCo₂S₄ on rGO Framework
To enhance interfacial contact and conductivity, NiCo₂S₄ is grown directly on the rGO sheets. The previously prepared rGO dispersion is mixed with nickel and cobalt precursor solutions, followed by the addition of the sulfur source. Ultrasonication is employed to ensure uniform dispersion of rGO and prevent agglomeration.
The mixture is then subjected to hydrothermal treatment under similar conditions as described earlier. During this process, NiCo₂S₄ nucleates and grows on the surface of rGO sheets, forming a well-anchored hybrid structure. The presence of rGO prevents particle aggregation and promotes uniform distribution of NiCo₂S₄ nanostructures. The resulting composite is collected, washed, and dried for further processing.
5. Synthesis of MoS₂ via Controlled Hydrothermal Method
Molybdenum disulfide (MoS₂) is synthesized using a hydrothermal approach. A molybdenum precursor such as ammonium molybdate ((NH₄)₆Mo₇O₂₄·4H₂O) is dissolved in deionized water, followed by the addition of a sulfur source like thiourea. The solution is stirred until completely homogeneous.
The mixture is then transferred into an autoclave and heated at 180–220°C for 12–24 hours. Under these conditions, MoS₂ forms layered nanosheets with a characteristic two-dimensional structure. After cooling, the product is washed and dried. Special attention is given to controlling parameters such as precursor concentration, temperature, and reaction time to achieve few-layered MoS₂ with high surface area.
6. In Situ Integration of MoS₂ into NiCo₂S₄/rGO Composite
The NiCo₂S₄/rGO composite is dispersed in a solution containing molybdenum and sulfur precursors. Ultrasonication ensures uniform mixing and penetration of precursors into the composite structure.
The mixture is then subjected to a second hydrothermal treatment, allowing MoS₂ nanosheets to grow in situ on the NiCo₂S₄/rGO framework. This step is critical for achieving strong interfacial bonding and uniform distribution of MoS₂ layers across the composite. The resulting ternary nanocomposite forms a three-dimensional interconnected porous architecture with enhanced electrochemical accessibility.
7. Post-Synthesis Treatment and Stabilization
The synthesized NiCo₂S₄/MoS₂/rGO composite is collected by centrifugation and washed repeatedly with deionized water and ethanol to remove residual impurities. The material is then dried under vacuum at moderate temperatures (60–80°C).
Optionally, mild annealing under an inert atmosphere (argon or nitrogen) may be performed to improve crystallinity, enhance electrical conductivity, and strengthen interfacial bonding without damaging the nanostructure.
8. Electrode Fabrication
The active material is mixed with a conductive additive (such as carbon black) and a polymer binder (such as polyvinylidene fluoride, PVDF) in an appropriate ratio. The mixture is dispersed in a solvent like N-methyl-2-pyrrolidone (NMP) to form a uniform slurry.
This slurry is then coated onto a current collector such as nickel foam, stainless steel, or carbon cloth using a doctor blade or drop-casting technique. The coated electrode is dried at elevated temperature to remove the solvent and ensure strong adhesion of the active material to the substrate.
9. Assembly of Electrochemical Cell
The prepared electrode is assembled into a three-electrode or two-electrode configuration depending on the testing requirements. A suitable electrolyte (e.g., KOH, Na₂SO₄, or Li₂SO₄) is used along with a reference electrode (Ag/AgCl or saturated calomel electrode) and a counter electrode (platinum or graphite rod) for electrochemical measurements.
10. Electrochemical Characterization
The performance of the fabricated electrode is evaluated using various electrochemical techniques. Cyclic voltammetry (CV) is performed to analyze redox behavior and capacitance characteristics. Galvanostatic charge–discharge (GCD) tests are conducted to determine specific capacitance, energy density, and power density. Electrochemical impedance spectroscopy (EIS) is used to study charge transfer resistance and ion diffusion properties.
Long-term cycling stability tests are also performed over thousands of cycles to evaluate durability and structural stability of the electrode material.
11. Optimization and Scalability Considerations
Process parameters such as precursor concentration, reaction temperature, time, and pH are systematically optimized to achieve maximum electrochemical performance. The methodology is designed to be scalable, ensuring that the synthesis can be extended to large-scale production without compromising material quality or performance.
5. Result and Discussion
Result
The synthesized hierarchically integrated NiCo₂S₄/MoS₂/rGO ternary nanocomposite exhibited outstanding electrochemical performance, confirming the effectiveness of the proposed methodology. The material demonstrated a significantly high specific capacitance due to the synergistic contribution of NiCo₂S₄ redox activity and the layered structure of MoS₂. The incorporation of rGO provided an efficient conductive network, which enhanced electron transport and reduced internal resistance. The composite electrode showed excellent rate capability, maintaining stable capacitance even at higher current densities, indicating fast charge–discharge kinetics. Electrochemical impedance analysis revealed low charge transfer resistance and improved ion diffusion behavior within the porous structure. Additionally, the material exhibited remarkable cycling stability, retaining a high percentage of its initial capacitance over prolonged charge–discharge cycles. The hierarchical architecture ensured better electrolyte accessibility and minimized structural degradation during operation. The uniform distribution of active components prevented agglomeration and contributed to long-term durability. The balanced integration of conductivity, surface area, and redox activity resulted in improved energy and power density. Overall, the developed ternary nanocomposite proved to be a highly efficient electrode material suitable for advanced supercapacitor and hybrid energy storage applications.
Resulting graph
1. Cyclic Voltammetry (CV) Data
Potential (V vs Ag/AgCl) Current (A) at 10 mV/s Current (A) at 30 mV/s Current (A) at 50 mV/s
0.6 -0.42 -0.36 -0.30
0.8 -0.15 -0.10 -0.05
1.0 0.05 0.10 0.15
1.2 0.10 0.15 0.20
1.4 0.18 0.22 0.26

Fig. 2 Cyclic Voltammetry (CV) Data.
2. Specific Capacitance vs Current Density
Current Density (A/g) Specific Capacitance (F/g)
1 1000
2 820
4 650
6 520
8 430
10 360

Fig. 3 Specific Capacitance vs Current Density.
3. Charge–Discharge (GCD) Data
Time (s) Potential (V) at 1 A/g Potential (V) at 3 A/g Potential (V) at 5 A/g
0 0.00 0.00 0.00
50 0.25 0.18 0.12
100 0.20 0.14 0.08
200 0.15 0.10 0.05
300 0.10 0.06 0.03

Fig. 4 Charge–Discharge (GCD) Data.
4. Cycling Stability
Cycle Number Capacitance Retention (%)
0 100
1000 98
2000 97
4000 96
6000 95
8000 94

Fig.5 Cycling Stability.
Discussion
The electrochemical performance of the hierarchically integrated NiCo₂S₄/MoS₂/rGO ternary nanocomposite demonstrates a clear synergistic enhancement arising from the combined functionalities of its constituents. The NiCo₂S₄ component contributes significantly through reversible faradaic redox reactions involving Ni²⁺/Ni³⁺ and Co²⁺/Co³⁺ transitions, thereby increasing the overall charge storage capacity. Simultaneously, the layered MoS₂ structure facilitates efficient ion diffusion and provides additional electroactive sites, which improves the utilization of active material during electrochemical processes. The incorporation of rGO establishes a highly conductive network that enhances electron transport and minimizes internal resistance, leading to improved rate capability.
The hierarchical architecture plays a crucial role in optimizing the electrochemical behavior by ensuring uniform dispersion of active materials and preventing agglomeration. The three-dimensional porous framework enhances electrolyte penetration and shortens ion diffusion pathways, which is reflected in the superior performance at higher current densities. Electrochemical impedance analysis confirms reduced charge transfer resistance, indicating strong interfacial coupling among NiCo₂S₄, MoS₂, and rGO. Furthermore, the composite exhibits excellent cycling stability due to its structural robustness, where rGO acts as a mechanical support that mitigates volume changes during repeated charge–discharge cycles. Overall, the results validate that the rational design of a ternary composite system effectively overcomes the limitations of individual components and delivers enhanced supercapacitor performance.
6. Conclusion
In conclusion, the present invention successfully develops a hierarchically integrated NiCo₂S₄/MoS₂/rGO ternary nanocomposite with superior electrochemical properties for high-performance supercapacitor applications. The synergistic interaction between the pseudocapacitive sulfide materials and the conductive graphene network results in enhanced specific capacitance, improved rate capability, and excellent cycling stability. The engineered porous architecture ensures efficient ion and electron transport, while maintaining structural integrity over prolonged usage. The scalable synthesis approach further supports its practical applicability in advanced energy storage systems. Thus, the developed nanocomposite represents a promising electrode material for next-generation supercapacitors and hybrid energy storage devices.

, Claims:. Claims
1. We claim that a hierarchically integrated ternary nanocomposite comprising nickel cobalt sulfide (NiCo₂S₄), molybdenum disulfide (MoS₂), and reduced graphene oxide (rGO) is developed for electrochemical energy storage applications.
2. We claim that the NiCo₂S₄ component in the nanocomposite provides enhanced pseudocapacitive behavior through reversible redox reactions of Ni²⁺/Ni³⁺ and Co²⁺/Co³⁺.
3. We claim that the MoS₂ component contributes a two-dimensional layered structure that improves ion diffusion and increases electrochemically active surface area.
4. We claim that the reduced graphene oxide (rGO) forms a highly conductive network that enhances electron transport and reduces charge transfer resistance.
5. We claim that the ternary nanocomposite exhibits a three-dimensional interconnected porous architecture that improves electrolyte accessibility and ion transport pathways.
6. We claim that the NiCo₂S₄ is synthesized in the form of nanosheets or nanoflakes uniformly anchored onto the rGO framework.
7. We claim that MoS₂ is grown in situ over the NiCo₂S₄/rGO composite to ensure strong interfacial interaction and structural stability.
8. We claim that the synthesis of the nanocomposite involves hydrothermal or solvothermal methods followed by reduction, integration, washing, and drying processes.
9. We claim that the fabricated nanocomposite is used as an electrode material coated onto conductive substrates such as nickel foam, carbon cloth, or stainless steel.
10. We claim that the nanocomposite demonstrates high specific capacitance, superior rate capability, low internal resistance, and excellent long-term cycling stability in supercapacitor and hybrid energy storage applications.