A team of chemists and physicists in Tamil Nadu, India, reports that a simple carbon coating can transform molybdenum disulfide, one of the most heavily studied two-dimensional materials of the past decade, into a far more capable workhorse for clean-energy and clean-water technologies. Writing in the journal Ionics, the researchers describe a hydrothermally synthesised hybrid in which activated carbon is fully integrated with layered MoS2, unlocking catalytic activity that the bare material leaves dormant. The resulting composite degraded nearly all of a model dye pollutant within ten minutes of visible-light exposure and, in a separate test, delivered supercapacitor performance figures that rank among the strongest reported for this class of low-cost electrodes.
The central problem the team set out to solve is a well-known quirk of transition metal dichalcogenides. MoS2 owes its catalytic and electrochemical behaviour largely to sulfur ions exposed at the edges of its sheets, where unsaturated bonds can grab onto reacting molecules and shuttle electrons. The vast flat faces of the sheets, known as basal planes, are largely catalytically inert; their sulfur atoms are fully coordinated and offer little purchase for reactions. For a material whose appeal lies in its enormous theoretical surface area, this is a frustrating paradox: most of the real estate is effectively switched off. Researchers have tried defect engineering, strain tuning and heterostructure design to wake up those basal planes, but many approaches are complex or expensive.
The Indian group, led by G. Rajasulochana of Arignar Anna Government Arts College in Namakkal with colleagues from Selvam College of Technology, Salem College of Engineering and Technology, and Government Arts and Science College in Komarapalayam, took a more direct route. They grew MoS2 in the presence of activated carbon under hydrothermal conditions, allowing the carbon to coat the growing two-dimensional crystals. According to the team, the activated carbon activates the basal plane surfaces of MoS2, increasing the density of catalytically and electrochemically active sites across the whole material rather than just along the sheet edges. In effect, the carbon turns the inert faces of the semiconductor into productive reaction surfaces while simultaneously contributing its own conductivity and porosity.
Structural characterisation confirmed that the strategy worked. X-ray diffraction showed carbon fully integrated into the MoS2 lattice assembly rather than sitting as a separate phase, a sign of intimate contact between the two components. Scanning electron microscopy then revealed how dramatically the carbon changes the material’s growth habit. Pure MoS2 synthesised under the same conditions forms sheet-like shapes, whereas the carbon-coated composite self-assembles into disc and flower-like structures. That morphological shift matters for practical devices: flower-like architectures expose abundant edges and interlayer spaces, shorten diffusion paths for ions and molecules, and help prevent the restacking of individual sheets that normally erodes the effective surface area of layered materials over time.
The photocatalytic results are the most eye-catching. The researchers dispersed the composite in a suspension of methylene blue, a common cationic dye used as a stand-in for the organic pollutants that textile and printing industries release into waterways, and illuminated it with visible light. The dye’s characteristic absorption peaks vanished within just ten minutes, corresponding to a degradation efficiency of 99.33 percent at an optimal carbon concentration of 0.005 molar. For context, many photocatalysts require hours of irradiation to achieve comparable removal, and many of the most active ones rely on ultraviolet light, which represents only a small fraction of sunlight. A material that works this fast under visible light is far better matched to real-world solar-driven water treatment.
The mechanism behind that speed, the team reports, involves hydroxyl radicals. When the photocatalyst absorbs visible photons, charge carriers are generated and migrate to the surface, where they react with water and dissolved oxygen to produce these highly reactive radical species. The hydroxyl radicals then attack the dye molecules, breaking their conjugated structures into smaller fragments until the colour and the pollutant itself are destroyed. The researchers found that visible-light irradiation broke down methylene blue greatly via this hydroxyl radical pathway, and the carbon coating plausibly assists by improving charge separation, giving photoexcited electrons a conductive escape route that reduces the recombination of electron-hole pairs, the process that ordinarily wastes most of a photocatalyst’s absorbed energy.
On the electrochemical side, the team built three-electrode cells in a 2 molar potassium hydroxide electrolyte to measure how well the composite stores charge as a supercapacitor electrode. The MoS2@C electrode achieved a specific capacitance of 1385 farads per gram at a current density of 1 ampere per gram, a remarkably high figure for a molybdenum disulfide-based material. Just as important for any device that must survive years of charge-discharge cycling, the electrode retained 89 percent of its capacitance after 10,000 cycles. That combination of high initial capacity and strong cycling stability suggests the carbon scaffold does more than boost raw performance; it also mechanically and electrically stabilises the MoS2 layers as they swell and contract during repeated ion insertion.
To demonstrate that the material could function in a realistic device rather than only in laboratory half-cells, the researchers assembled an asymmetric supercapacitor, pairing the MoS2@C electrode with a complementary counter electrode. The full cell delivered an energy density of 231 watt-hours per kilogram alongside a power density of 1137 watts per kilogram. Energy density describes how much charge a device can pack away; power density describes how quickly it can deliver it. Achieving both at high levels simultaneously is the central challenge of energy storage, since batteries typically offer high energy but modest power, while conventional capacitors offer power but little energy. An asymmetric device with these figures, built from inexpensive and abundant constituents, points toward supercapacitors that could buffer renewable electricity or power portable electronics with rapid charging.
The economic argument is a recurring theme in the paper. The authors frame the 2-dimensional layered carbon-coated MoS2 as a cost-effective material for both photocatalytic and electrochemical applications, and the ingredients support that claim. Molybdenum and sulfur are abundant and cheap compared with the noble metals often used in catalysis, activated carbon can be produced from a wide range of carbonaceous precursors, and the hydrothermal synthesis is a standard, scalable technique requiring no exotic equipment or vacuum processing. The work was carried out without dedicated funding, according to the authors’ declaration, underscoring that the advance rests on clever materials design rather than resource-intensive fabrication.
The study also fits into a broader research wave connecting layered dichalcogenides with carbon materials. Previous efforts have combined MoS2 with graphene, carbon nanotubes, carbon nanofibres and porous tubular carbons for supercapacitors, and with graphitic carbon nitride or graphene for photocatalysis. What distinguishes the new report is the dual functionality from a single synthesis and the specific claim that activated carbon wakes up the basal planes, converting the material’s largest but least useful surfaces into active ones. If that activation mechanism can be generalised to other dichalcogenides such as WS2 or MoSe2, the implications could extend to hydrogen evolution catalysis, sensing and battery electrodes. For now, the Tamil Nadu team’s hybrid stands as a striking demonstration that sometimes the cheapest modification, a coat of carbon, can switch on the hidden potential of a celebrated but underperforming material, simultaneously cleaning polluted water and storing renewable electricity with record-setting efficiency.
Subject of Research: Activated carbon-coated two-dimensional MoS2 hybrid for photocatalytic dye degradation and supercapacitor energy storage
Article Title: Highly efficient 2-dimensional layered MoS2@activated carbon hybrid for electrochemical and photocatalytic applications
Article References: Rajasulochana, G., Seenivasan, S., Vijayakumar, P., Jayanthi, K., & Sivakumar, P. (2026). Highly efficient 2-dimensional layered MoS2@activated carbon hybrid for electrochemical and photocatalytic applications. Ionics. https://doi.org/10.1007/s11581-026-07559-z
Image Credits: AI Generated
DOI: 10.1007/s11581-026-07559-z
Keywords: MoS2, activated carbon, photocatalysis, supercapacitors, methylene blue degradation, transition metal dichalcogenides, hydrothermal synthesis, basal plane activation, energy storage, visible light photocatalyst, hydroxyl radicals, asymmetric supercapacitor
News Source: Denise Maddox. (October 11, 2026). Carbon-Coated MoS2 Delivers Record Supercapacitor Power and Rapid Dye Breakdown. Scienmag.
