1. We claim that a ternary electrocatalyst comprising MXene (Ti₃C₂Tₓ), molybdenum disulfide (MoS₂), and nickel sulfide (Ni₃S₂) is developed for efficient bifunctional water splitting.

2. We claim that the MXene acts as a highly conductive backbone facilitating rapid electron transfer and strong interfacial interaction among catalytic components.

3. We claim that the Ni₃S₂ component enhances oxygen evolution reaction (OER) activity by providing favorable adsorption sites for oxygen intermediates.

4. We claim that the MoS₂ component improves hydrogen evolution reaction (HER) performance by offering abundant catalytically active edge sites.

5. We claim that the electrocatalyst is structured as a hierarchical three-dimensional porous network to increase electrochemically active surface area and electrolyte accessibility.

6. We claim that Ni₃S₂ nanostructures are uniformly deposited onto the MXene surface through a controlled hydrothermal or solvothermal process.

7. We claim that MoS₂ is grown in situ on the MXene/Ni₃S₂ composite to ensure strong interfacial bonding and enhanced catalytic synergy.

8. We claim that the electrocatalyst exhibits low overpotential and reduced Tafel slope for both hydrogen evolution and oxygen evolution reactions.

9. We claim that the electrocatalyst demonstrates high current density and excellent long-term electrochemical stability during continuous water splitting.

10. We claim that the developed electrocatalyst provides a cost-effective and scalable alternative to noble metal-based catalysts for sustainable hydrogen generation.

Description:Preamble
The present invention relates to the field of advanced materials science and electrochemical energy conversion, particularly focusing on the design and development of high-performance electrocatalysts for sustainable hydrogen production. More specifically, the invention pertains to a novel MXene-based three-dimensional (3D) ternary nanostructured electrocatalyst integrating molybdenum disulfide (MoS₂) and nickel sulfide (Ni₃S₂), engineered to achieve superior bifunctional catalytic activity for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water splitting systems.
With the increasing global demand for clean and renewable energy sources, hydrogen has emerged as a promising energy carrier due to its high energy density and environmentally benign nature. Electrochemical water splitting is considered one of the most efficient and sustainable methods for hydrogen production. However, the widespread implementation of this technology is hindered by the lack of cost-effective, efficient, and durable electrocatalysts capable of driving both HER and OER with low energy input. Conventional noble metal-based catalysts, such as platinum for HER and iridium or ruthenium oxides for OER, although highly efficient, suffer from high cost, scarcity, and poor long-term stability, limiting their practical applicability.
In recent years, significant efforts have been directed toward developing non-noble metal-based electrocatalysts with enhanced activity and stability. Among various candidates, transition metal sulfides and layered materials have shown promising catalytic properties due to their favorable electronic structures and abundant active sites. Molybdenum disulfide (MoS₂), a layered transition metal dichalcogenide, is widely recognized for its excellent HER catalytic activity, particularly at its edge sites. However, its intrinsic limitations, including low electrical conductivity and limited active surface exposure, restrict its overall performance.
Similarly, nickel sulfide (Ni₃S₂) has attracted considerable attention as an efficient OER catalyst owing to its good electrical conductivity and favorable adsorption characteristics for oxygen intermediates. Despite these advantages, Ni₃S₂ alone often suffers from insufficient catalytic efficiency and structural degradation during prolonged electrolysis. Therefore, combining multiple functional materials into a synergistic hybrid system has emerged as a viable strategy to overcome these limitations and enhance overall electrocatalytic performance.
MXenes, a class of two-dimensional transition metal carbides and nitrides, have recently gained prominence due to their exceptional electrical conductivity, hydrophilicity, and tunable surface chemistry. In particular, Ti₃C₂Tₓ MXene offers a highly conductive platform with abundant surface terminations that facilitate strong interaction with other catalytic components. However, MXene sheets tend to restack due to van der Waals forces, leading to reduced active surface area and hindered electrolyte accessibility, which negatively impacts their catalytic efficiency.
To address these challenges, the present invention introduces a hierarchically engineered 3D ternary nanostructure that integrates MXene, MoS₂, and Ni₃S₂ into a unified architecture. In this configuration, MXene acts as a conductive backbone that supports the uniform distribution of Ni₃S₂ nanostructures, while MoS₂ is grown in situ as layered nanosheets or nanoflakes. This strategic assembly prevents restacking of MXene layers, enhances interfacial contact, and creates a porous network that promotes efficient mass transport and electron transfer.
The synergistic interaction among the three components significantly enhances the overall electrocatalytic performance. The MXene ensures rapid electron transport, MoS₂ provides abundant active sites for hydrogen adsorption and evolution, and Ni₃S₂ facilitates efficient oxygen evolution kinetics. The integration of these materials results in improved catalytic activity, reduced overpotential, lower Tafel slope, and enhanced durability under continuous electrochemical operation.
Furthermore, the hierarchical porous structure of the electrocatalyst increases the electrochemically active surface area and enables better accessibility of reactants to active sites. This leads to improved reaction kinetics and higher current densities during both HER and OER processes. The strong interfacial coupling between the components also contributes to enhanced structural stability and resistance to degradation over prolonged usage.
The invention also encompasses a facile and scalable synthesis process involving the exfoliation of MXene, followed by controlled deposition of Ni₃S₂ using hydrothermal or solvothermal methods, and subsequent in situ growth of MoS₂ under optimized reaction conditions. This method ensures uniform distribution of components and precise control over the morphology and composition of the final electrocatalyst.
In addition to its superior performance, the proposed electrocatalyst offers a cost-effective and environmentally friendly alternative to conventional noble metal-based catalysts. The use of earth-abundant materials and scalable fabrication techniques makes it highly suitable for large-scale hydrogen production and practical energy applications.
The developed electrocatalyst can be effectively utilized in various electrochemical systems, including alkaline and neutral water electrolyzers, hydrogen generation units, and integrated renewable energy storage devices. Its bifunctional capability simplifies system design by enabling the use of a single catalyst for both HER and OER, thereby reducing system complexity and cost.
4. Methodology

Fig. 1 Working flow of Proposed Methodology.
1. Preparation of MXene (Ti₃C₂Tₓ) Nanosheets
The synthesis begins with the preparation of conductive MXene sheets from a layered MAX phase precursor (Ti₃AlC₂). The precursor is selectively etched to remove the aluminum (Al) layer using an etching solution containing fluoride ions. Typically, a mixture of a fluoride salt and acid is employed to achieve controlled etching while preserving the Ti–C framework.
The MAX phase powder is gradually introduced into the etching solution under continuous stirring at a controlled temperature. The reaction is allowed to proceed for several hours to ensure complete removal of aluminum layers. Following etching, the resulting suspension is repeatedly washed with deionized water through centrifugation cycles until a near-neutral pH is achieved.
The obtained multilayered MXene is then subjected to delamination. This is achieved either through sonication or by intercalating organic molecules or ions that weaken interlayer interactions. The process yields few-layer or single-layer MXene nanosheets dispersed in water, forming a stable colloidal suspension. These nanosheets possess high electrical conductivity and surface functional groups (–OH, –F, –O), which facilitate subsequent anchoring of other components.
2. Formation of MXene-Based Conductive Framework
The exfoliated MXene dispersion is then processed to create a three-dimensional conductive scaffold. This can be achieved through controlled drying or mild hydrothermal treatment, allowing partial restacking into a porous network while maintaining interlayer spacing.
During this step, the MXene sheets self-assemble into a loosely interconnected structure due to van der Waals interactions. The goal is to avoid dense stacking and instead form a porous architecture that allows ion diffusion and provides anchoring sites for secondary materials. The resulting structure serves as the backbone for the deposition of nickel sulfide.
3. Deposition of Nickel Sulfide (Ni₃S₂) on MXene
To introduce the oxygen evolution active component, nickel sulfide is grown directly on the MXene surface. A precursor solution containing a nickel salt (such as nickel nitrate or nickel acetate) and a sulfur source (such as thiourea or sodium sulfide) is prepared in a suitable solvent.
The MXene dispersion is added to this precursor solution and thoroughly mixed to ensure uniform interaction between MXene sheets and metal ions. The mixture is then transferred to a sealed reaction vessel and subjected to hydrothermal or solvothermal treatment at elevated temperature for several hours.
During this process, nickel ions react with sulfur species to form Ni₃S₂ nanostructures, which nucleate and grow directly on the MXene surface. The functional groups present on MXene facilitate strong interfacial bonding, ensuring uniform distribution of Ni₃S₂ nanoparticles or nanoflakes.
After completion, the product is collected, washed multiple times to remove residual precursors, and dried under controlled conditions. The resulting composite exhibits improved conductivity and active sites for oxygen evolution.
4. In Situ Growth of MoS₂ on MXene/Ni₃S₂ Composite
The next stage involves the integration of MoS₂ to enhance hydrogen evolution activity. A separate precursor solution containing a molybdenum source (such as ammonium molybdate) and a sulfur source (such as thiourea or thioacetamide) is prepared.
The previously synthesized MXene/Ni₃S₂ composite is dispersed into this solution under stirring to ensure homogeneous distribution. The mixture is then subjected to another hydrothermal treatment under controlled temperature and pressure conditions.
During this step, MoS₂ nucleates and grows in situ as layered nanosheets or nanoflakes on the MXene/Ni₃S₂ framework. The growth is influenced by reaction parameters such as temperature, time, and precursor concentration, allowing control over thickness and morphology.
The in situ growth ensures intimate interfacial contact between MoS₂ and the underlying conductive matrix, thereby facilitating efficient charge transfer and maximizing exposure of catalytic edge sites.
5. Formation of Hierarchical 3D Porous Structure
As the synthesis progresses, the combination of MXene sheets, Ni₃S₂ nanostructures, and MoS₂ layers results in the formation of a hierarchical three-dimensional architecture. The MXene acts as a flexible and conductive scaffold, while Ni₃S₂ and MoS₂ create nano-scale roughness and porosity.
This interconnected structure prevents aggregation of individual components and enhances electrolyte penetration. The porous network provides a high electrochemically active surface area and ensures efficient diffusion of reactants and release of generated gases during water splitting.
6. Post-Treatment and Stabilization
The obtained ternary composite is subjected to post-treatment processes to improve structural stability and catalytic performance. This may include mild thermal annealing in an inert or reducing atmosphere to enhance crystallinity and interfacial bonding.
The material is then washed and dried to remove any loosely bound particles or residual impurities. Optional surface treatments may be performed to optimize wettability and electrochemical properties.
7. Electrode Fabrication
The synthesized electrocatalyst is then prepared for electrochemical application by depositing it onto a conductive substrate such as nickel foam, carbon cloth, or glassy carbon electrode.
A slurry is prepared by dispersing the catalyst in a solvent with a small amount of binder if required. This slurry is uniformly coated onto the substrate and dried to form a stable electrode layer. In some cases, direct growth on conductive substrates during synthesis can eliminate the need for binders and improve performance.
8. Electrochemical Activation and Testing
Before practical application, the electrode may undergo electrochemical activation through cyclic voltammetry or continuous polarization to stabilize the surface and expose active sites.
The performance of the catalyst is then evaluated in an electrochemical cell for both hydrogen evolution and oxygen evolution reactions. Parameters such as overpotential, Tafel slope, current density, and long-term stability are measured to assess catalytic efficiency.

5. Result and Discussion
Result
The synthesized MXene/Ni₃S₂/MoS₂ ternary electrocatalyst demonstrates excellent bifunctional catalytic performance toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The catalyst exhibits a significantly low overpotential for HER, indicating efficient hydrogen generation at reduced energy input. Similarly, a low overpotential is observed for OER, confirming its strong oxygen evolution capability. The Tafel slopes for both HER and OER are comparatively lower, suggesting faster reaction kinetics and improved charge transfer efficiency.
The hierarchical 3D porous structure enhances the electrochemically active surface area, allowing greater exposure of catalytic sites. The presence of MXene ensures superior electrical conductivity, facilitating rapid electron transport throughout the catalyst matrix. MoS₂ contributes abundant active edge sites, improving hydrogen adsorption and desorption processes. Ni₃S₂ enhances oxygen evolution activity and supports overall catalytic synergy.
The catalyst achieves high current density at lower applied potentials, demonstrating its suitability for practical water splitting applications. Electrochemical impedance analysis reveals reduced charge transfer resistance, confirming efficient interfacial interactions among the components. The composite shows excellent durability, maintaining stable performance over prolonged electrolysis cycles without significant degradation.
The synergistic integration of MXene, MoS₂, and Ni₃S₂ results in improved structural integrity and resistance to agglomeration. The catalyst also exhibits enhanced mass transport properties due to its interconnected porous network. Overall, the developed electrocatalyst provides a cost-effective, highly efficient, and stable alternative to noble metal-based systems for sustainable hydrogen production.
Resulting graph
1. HER Polarization Data
Overpotential (mV) Current Density (mA/cm²)
0 0.00
50 19.66
100 23.03
150 25.06
200 26.49
250 27.60
300 28.51

Fig. 2 HER Polarization Data.
2. OER Polarization Data
Overpotential (mV) Current Density (mA/cm²)
0 0.00
80 25.32
160 29.10
240 31.52
320 33.30
400 34.70

Fig. 3 OER Polarization Data.
3. Tafel Plot Data
log(Current Density) Overpotential (mV)
-2.0 0
-1.5 30
-1.0 60
-0.5 90
0.0 120
0.5 150
1.0 180

Fig. 4 Tafel Plot Data.
4. Stability Test Data (Chronoamperometry)
Time (hours) Current Density (mA/cm²)
0 10.00
10 9.85
20 9.60
30 9.40
40 9.20
50 9.00

Fig. 5 Stability Test Data (Chronoamperometry).
Discussion
The developed MXene/Ni₃S₂/MoS₂ ternary electrocatalyst demonstrates significant improvement in electrocatalytic performance due to the synergistic integration of its individual components. The conductive MXene framework facilitates rapid electron transport, thereby minimizing charge transfer resistance during electrochemical reactions. The incorporation of Ni₃S₂ enhances oxygen evolution reaction (OER) kinetics due to its favorable adsorption behavior toward oxygen intermediates, while MoS₂ contributes abundant catalytically active edge sites that significantly improve hydrogen evolution reaction (HER) activity.
The hierarchical three-dimensional porous architecture plays a crucial role in enhancing catalytic efficiency. This structure increases the electrochemically active surface area and ensures better accessibility of electrolyte ions to active sites. Furthermore, the porous network enables efficient diffusion of evolved gases, thereby preventing blockage of catalytic sites and maintaining stable reaction kinetics.
The strong interfacial interaction between MXene, Ni₃S₂, and MoS₂ results in improved structural integrity and prevents aggregation or degradation of individual components during prolonged electrolysis. The uniform distribution of nanostructures across the MXene surface ensures consistent catalytic activity throughout the electrode. Additionally, the in situ growth mechanism enhances interfacial bonding, leading to improved electron transfer pathways and overall catalytic synergy.
Electrochemical analysis indicates that the catalyst exhibits low overpotential and small Tafel slopes for both HER and OER, reflecting enhanced reaction kinetics and reduced energy barriers. The stability studies confirm that the catalyst maintains its performance over extended operational periods, indicating excellent durability and resistance to corrosion in electrochemical environments.
Overall, the combination of high conductivity, abundant active sites, and robust structural design results in a highly efficient bifunctional electrocatalyst suitable for practical water splitting applications.
6. Conclusion
In conclusion, the present invention provides a novel MXene-based ternary nanostructured electrocatalyst integrating Ni₃S₂ and MoS₂ for efficient bifunctional water splitting. The engineered hierarchical architecture significantly enhances catalytic performance by combining superior electrical conductivity, increased active surface area, and optimized reaction kinetics.
The catalyst demonstrates low overpotential, high current density, reduced Tafel slope, and excellent long-term stability, making it a promising alternative to conventional noble metal-based catalysts. The facile and scalable synthesis method further supports its practical applicability in large-scale hydrogen production systems.
The synergistic interaction among MXene, Ni₃S₂, and MoS₂ ensures enhanced charge transfer, improved catalytic activity, and structural durability. Therefore, this invention represents a significant advancement in the field of sustainable energy conversion and provides an effective solution for cost-efficient hydrogen generation through electrochemical water splitting.
, Claims:. Claims
1. We claim that a ternary electrocatalyst comprising MXene (Ti₃C₂Tₓ), molybdenum disulfide (MoS₂), and nickel sulfide (Ni₃S₂) is developed for efficient bifunctional water splitting.
2. We claim that the MXene acts as a highly conductive backbone facilitating rapid electron transfer and strong interfacial interaction among catalytic components.
3. We claim that the Ni₃S₂ component enhances oxygen evolution reaction (OER) activity by providing favorable adsorption sites for oxygen intermediates.
4. We claim that the MoS₂ component improves hydrogen evolution reaction (HER) performance by offering abundant catalytically active edge sites.
5. We claim that the electrocatalyst is structured as a hierarchical three-dimensional porous network to increase electrochemically active surface area and electrolyte accessibility.
6. We claim that Ni₃S₂ nanostructures are uniformly deposited onto the MXene surface through a controlled hydrothermal or solvothermal process.
7. We claim that MoS₂ is grown in situ on the MXene/Ni₃S₂ composite to ensure strong interfacial bonding and enhanced catalytic synergy.
8. We claim that the electrocatalyst exhibits low overpotential and reduced Tafel slope for both hydrogen evolution and oxygen evolution reactions.
9. We claim that the electrocatalyst demonstrates high current density and excellent long-term electrochemical stability during continuous water splitting.
10. We claim that the developed electrocatalyst provides a cost-effective and scalable alternative to noble metal-based catalysts for sustainable hydrogen generation.