The starting point of the work is deceptively simple. Clam shells, composed largely of calcium carbonate, are converted through controlled thermal and chemical treatment into a honeycomb-structured porous activated carbon, which the researchers abbreviate CAC. This architecture is exactly what materials scientists prize in an electrode or catalyst support: an interconnected network of pores at multiple length scales that offers enormous internal surface area for ions to access, along with a conductive carbon scaffold that can anchor catalytically active particles. By sourcing the carbon from biowaste rather than fossil-derived precursors, the team also sidesteps one of the persistent criticisms of advanced energy materials, namely that their manufacture can carry a heavy environmental footprint of its own.

Onto this biological carbon scaffold the researchers deposited sphere-like particles of a cerium-doped lanthanum cobaltite, a perovskite oxide of the general formula LaCoO3 in which a small fraction of the lanthanum sites is occupied by cerium atoms. Perovskite oxides of this ABO3 family have attracted intense interest in recent years because their compositions can be tuned almost endlessly, allowing chemists to adjust their electronic structure, optical absorption and surface chemistry. Doping is the classic lever: substituting foreign cations into the crystal lattice distorts the structure, creates defects such as oxygen vacancies, and can dramatically improve charge transport and light harvesting. In this case, the cerium substitution modifies the cobaltite’s semiconductor characteristics in ways that make it a more effective visible-light photocatalyst and a more capable charge-storage material.

The synthesis itself was deliberately kept low-tech. The composite, designated CAC/LC:Ce, was prepared by a facile hydrothermal method, in which the precursor solution and the carbon support are heated together in a sealed vessel, allowing the perovskite spheres to nucleate and grow directly on the carbon surface. Hydrothermal processing is widely favored in green chemistry because it operates at modest temperatures, uses water as the reaction medium and avoids many of the toxic solvents and elaborate vacuum steps associated with other nanomaterial fabrication routes. The result is a one-pot marriage of biowaste-derived carbon and engineered oxide that could, in principle, be scaled without exotic equipment.

Characterization was correspondingly thorough. The team probed the crystal structure of all three materials with X-ray diffraction, examined their morphology with field-emission scanning electron microscopy and high-resolution transmission electron microscopy, and confirmed chemical composition and surface states using Fourier-transform infrared spectroscopy, UV-Vis spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray analysis and Brunauer-Emmett-Teller surface area measurements. Two electrochemical techniques added crucial mechanistic depth. Mott-Schottky analysis revealed the semiconductor type and band structure of the cerium-doped cobaltite and the composite, mapping out the energy levels that govern how photogenerated electrons and holes separate, while transient photocurrent measurements under intermittent illumination demonstrated how efficiently the materials shuttle light-excited charges before they recombine and waste the absorbed energy.

The environmental half of the story centers on bromophenol blue, a widely used phenolic dye that serves as a stand-in for the colored organic pollutants that textile and dyeing industries discharge into waterways. Under visible-light illumination, the three materials showed a clear performance hierarchy in dye removal percentage. The clam shell carbon alone discolored 75 percent of the dye, the cerium-doped cobaltite managed 86 percent, and the combined composite reached 98 percent. That near-complete removal reflects a synergy between the two components: the porous carbon adsorbs dye molecules onto its extensive surface, concentrating them near the perovskite particles, which then generate reactive oxygen species under light that chemically dismantle the adsorbed pollutants. Scavenger experiments, in which specific radical quenchers are added to identify which reactive species dominate, allowed the team to pin down the key actors in the degradation chemistry.

Just as important as the headline efficiency is durability. Many photocatalysts lose activity after a few cycles as active sites are blocked by intermediates or the material itself degrades. The CAC/LC:Ce composite retained a 95 percent dye removal value on its fourth consecutive run, a strong indication that the anchoring of the perovskite on the robust carbon framework protects the active phase. The researchers also used liquid chromatography-mass spectrometry to trace the intermediate species formed as the dye broke down, reconstructing a plausible degradation pathway rather than simply reporting that the color disappeared. That distinction matters, because a decolorized solution can still contain toxic fragments, and a responsible remediation technology must demonstrate that the end products are genuinely benign.

To address that concern directly, the team evaluated the treated water biologically. Phytotoxicity tests using fenugreek, Trigonella foenum-graecum, assessed whether the degraded dye solution would still harm seed germination and plant growth, while ecotoxicity screening in zebrafish probed effects on aquatic organisms. These assays are a relatively rare but welcome step in photocatalysis research, where many studies stop at the discoloration percentage. By checking that the remediated water is compatible with both plant and aquatic life, the authors provide evidence for the practical reuse potential of the treated effluent, which is the ultimate test of any water-treatment technology intended for real-world deployment.

The energy-storage half of the study is equally striking. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy were used to evaluate electrodes fabricated from each material. The specific capacitances came out at 240 farads per gram for the clam shell carbon, 381 farads per gram for the cerium-doped cobaltite, and 652 farads per gram for the composite, a value that places the hybrid among the more capable perovskite-carbon electrodes reported in the supercapacitor literature. The composite electrode also held on to 91 percent of its initial capacitance after 3000 charge-discharge cycles, showing that the faradaic reactions at the perovskite surface do not rapidly degrade the electrode. To test performance at the device level, the team assembled a two-electrode asymmetric supercapacitor cell using the plain clam shell carbon as the negative electrode and the composite as the positive electrode, a configuration that widens the operating voltage window and is the standard route toward practical energy and power densities.

Taken together, the study offers a template for what sustainable materials chemistry can look like when the circular economy is designed in from the first step rather than bolted on at the end. A waste stream from the seafood industry becomes a porous carbon; that carbon hosts a doped perovskite engineered for visible-light activity; the resulting composite simultaneously tackles dye pollution and grid-relevant energy storage; and the safety of the cleaned water is verified with living organisms rather than assumed. Challenges certainly remain before such materials leave the laboratory, including scaling hydrothermal synthesis, validating performance with real textile effluents rather than model dyes, and demonstrating device-level cycling over far more than 3000 cycles. But the underlying message is compelling: with thoughtful design, the same humble material can help solve two of the defining problems of the coming decades, dirty water and the need for affordable energy storage, using nothing more exotic than clam shells, cerium and sunlight.

Subject of Research: A clam shell-derived activated carbon supporting cerium-doped lanthanum cobaltite perovskite for photocatalytic dye degradation and supercapacitor energy storage

Article Title: Sustainable synthesis of La–Ce mixed cobaltite anchored on clam shell-derived porous activated carbon for electrochemical energy storage and environmental remediation

Article References: Sustainable synthesis of La–Ce mixed cobaltite anchored on clam shell-derived porous activated carbon for electrochemical energy storage and environmental remediation. (n.d.). https://doi.org/10.1007/s11581-026-07489-w

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07489-w

Keywords: clam shell activated carbon, perovskite, LaCoO3, cerium doping, photocatalysis, dye degradation, supercapacitor, asymmetric cell, biomass-derived carbon, water remediation, hydrothermal synthesis, specific capacitance

Solution-combustion synthesis is a deceptively simple technique with dramatic chemistry at its core. Metal salt precursors are dissolved together with an organic fuel, and the mixture is heated until it ignites. The combustion reaction then races through the solution in seconds, releasing intense heat and a rush of gases that tear the growing crystals apart into nanoscale grains. The fuel choice matters enormously. Conventional fuels such as urea or glycine work well but carry environmental and cost penalties. Honey, by contrast, is a natural cocktail of reducing sugars—chiefly glucose and fructose—that supplies both the reducing power and the carbonaceous framework needed to drive the reaction, while its viscosity and sugar content help control how the precursor solution gels and burns.

In the reported synthesis, thorium and zinc precursors were combined with honey as the combustible fuel, and the mixture was ignited to yield the doped oxide in a single rapid step. The team then subjected the product to a battery of characterization techniques. Powder X-ray diffraction confirmed that the material retained the hexagonal wurtzite crystal structure characteristic of zinc oxide, with thorium incorporated into the lattice and no detectable impurity phases, indicating high phase purity. Scanning electron microscopy and high-resolution transmission electron microscopy revealed the nanocrystalline character of the grains, while energy-dispersive X-ray analysis verified the elemental composition and Fourier-transform infrared spectroscopy probed the surface chemical groups. Together, these measurements established that the honey route had produced exactly the doped, pure, nanoscale wurtzite phase the researchers were aiming for.

Why dope zinc oxide with thorium at all? Zinc oxide is a workhorse of materials science—cheap, abundant, non-toxic by comparison with many metal oxides, and versatile in electronics and catalysis. But its performance in energy storage and visible-light photocatalysis is limited by its intrinsic properties: it is a wide-bandgap semiconductor that absorbs mainly ultraviolet light, and its electrical conductivity and charge-storage behavior leave room for improvement. Substituting foreign metal ions into the wurtzite lattice introduces defects, alters electronic states, and can create additional active sites for both ion adsorption and charge transfer. Thorium, a large tetravalent actinide ion, distorts the local lattice environment in ways that the authors link to the material’s enhanced electrochemical and optical behavior.

The supercapacitor results were the headline numbers of the study. When tested as an electrode material, the ThZnO3 nanomaterial delivered a specific capacitance of 344 farads per gram at a current density of 1 ampere per gram—a substantial figure for a metal oxide electrode. The material also achieved an energy density of 47.78 watt-hours per kilogram at a power density of 500 watts per kilogram, a combination that matters because supercapacitors typically excel at power density while lagging behind batteries in energy density. Bridging that gap is one of the central challenges in electrochemical energy storage, and electrode materials that push energy density upward without sacrificing the rapid charge-discharge capability that defines supercapacitors are keenly sought.

Supercapacitors store charge through ions accumulating at electrode surfaces and, in many metal oxides, through fast, reversible surface redox reactions. The performance of ThZnO3 fits this pseudocapacitive picture: doping creates more electroactive sites, and the nanoscale grain size shortens the diffusion paths that ions must travel, while the combustion-derived porosity gives the electrolyte access to a large interfacial area. The honey fuel contributes indirectly here as well, because the gases released during combustion leave behind a porous, high-surface-area architecture that would be harder to achieve with denser, conventionally calcined powders. The authors report that kinetic analysis of the electrochemical data supported these conclusions about how charge is stored in the material.

The second act of the study concerned water treatment. Malachite green is a triphenylmethane dye used historically in aquaculture and industry, and it is notoriously persistent and toxic in waterways. Under visible-light irradiation, just 1 milligram of the ThZnO3 nanomaterial degraded 90.01 percent of a 10 parts-per-million malachite green solution at neutral pH. That neutral-pH operation is significant, because many photocatalytic processes require acidic or alkaline conditions that complicate real-world deployment. The team backed up the degradation measurement with kinetic analysis showing the rate behavior of the reaction, and with scavenger studies designed to identify which reactive species—such as hydroxyl radicals, superoxide radicals, or photogenerated holes—do the chemical work of breaking the dye molecule apart.

Perhaps just as important as the headline efficiencies is what happened after the first use. Many promising photocatalysts degrade in performance or, worse, dissolve and release toxic metal ions into the water they are meant to clean. The researchers demonstrated that ThZnO3 maintained its structural integrity across multiple degradation cycles, with negligible leaching of metal ions into solution. That recyclability, combined with the material’s stability, addresses one of the most common failure modes that keeps laboratory photocatalysts out of practical water-treatment systems. For a material containing thorium—an element that raises regulatory and radiological questions in bulk form—the demonstration of negligible leaching is a particularly relevant finding for any future application discussion.

The study sits within a broader wave of green-synthesis research emerging from Indian and international laboratories, in which plant extracts, gels, and food-derived fuels replace synthetic reagents. Recent examples in the same journal and elsewhere include zinc oxide made with Triphala, a traditional herbal formulation, lanthanum oxide synthesized with lemon juice, and nickel oxide prepared with aloe vera gel. The appeal is twofold: these bio-derived fuels are inexpensive and widely available, and they often impart beneficial microstructure to the product. The Mysuru team’s honey route extends this toolbox to thorium-doped zinc oxide and shows that a kitchen staple can stand in for industrial fuel precursors without compromising crystallinity or phase purity.

Caveats remain before honey-made thorium-doped zinc oxide powers phones or cleans rivers. The electrochemical measurements were made at the laboratory electrode scale, and scaling up combustion synthesis of actinide-containing materials would face cost, safety, and regulatory hurdles that the study does not address. Thorium’s availability and handling requirements differ sharply from those of benign dopants such as nickel or cobalt. Still, the paper demonstrates a coherent proof of concept: a single, low-cost, rapid synthesis yielding a phase-pure nanomaterial that performs credibly in two of applied materials chemistry’s most competitive arenas. As the search intensifies for multifunctional materials that squeeze more value out of each synthesis step, the idea that a spoonful of honey can help light the way is likely to find an enthusiastic audience.

Subject of Research: Honey-assisted solution-combustion synthesis of thorium-doped zinc oxide nanomaterial for supercapacitor electrodes and visible-light photocatalytic dye degradation

Article Title: Multifunctional thorium-doped ZnO nanomaterial via honey-assisted solution-combustion route for supercapacitor performance and visible-light photocatalytic application

Article References: Jayadevappa, S., M. J., N. K., G. R., D., S. M., P., S, N. S., Kumar, K. N., V, L. R., & G. S., N. (2026). Multifunctional thorium-doped ZnO nanomaterial via honey-assisted solution-combustion route for supercapacitor performance and visible-light photocatalytic application. Ionics. https://doi.org/10.1007/s11581-026-07496-x

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07496-x

Keywords: zinc oxide, thorium doping, honey-assisted combustion synthesis, green synthesis, supercapacitor, specific capacitance, energy density, photocatalysis, malachite green, dye degradation, nanomaterials, wurtzite structure

The central idea behind the study is division of labor at the nanoscale. Bismuth oxide, in its alpha crystalline phase, is the redox workhorse of the electrode, shuttling charge through fast surface and near-surface reactions that give pseudocapacitors their battery-like storage capacity. Multi-walled carbon nanotubes contribute the opposite virtue: an electrically conductive, graphitic scaffold that lets electrons flow freely through the film, so that no particle of active oxide is ever more than a few nanometers from a current pathway. Precipitated calcium carbonate, a material more often associated with paper fillers and paints than with cutting-edge electrochemistry, plays the role of structural stabilizer, helping to maintain an open, interconnected mesoporous architecture that keeps electrolyte ions moving freely even when the electrode is packed with active material.

Verifying that all three components genuinely coexist, and cooperate, required an extensive characterization campaign. X-ray diffraction confirmed the presence of alpha-phase bismuth oxide, calcite-form calcium carbonate, and graphitic carbon nanotubes within the composite, while Fourier transform infrared spectroscopy added complementary chemical fingerprints of each constituent. Field-emission scanning electron microscopy revealed the morphology of the films, showing an interconnected network in which the different phases are intimately mixed rather than segregated. Brunauer-Emmett-Teller analysis of gas adsorption quantified the textural properties, confirming a mesoporous structure with pores in the size range that allows electrolyte ions to penetrate rapidly and access the interior surfaces of the electrode, a prerequisite for high-rate performance.

The electrochemical results are where the ternary design earns its keep. In cyclic voltammetry and galvanostatic charge-discharge tests, the Bi2O3/PCC/MWCNT composite achieved the highest specific capacitance of all electrodes investigated, reaching 1359.5 farads per gram at 1 ampere per gram. Even when the current density was raised tenfold to 10 amperes per gram, the electrode still delivered 899.6 farads per gram, a rate retention of 66.2 percent. That figure matters because it demonstrates that the composite does not merely store a lot of charge under gentle conditions; it can also release that charge quickly, which is precisely what supercapacitors are asked to do in applications ranging from regenerative braking to grid frequency regulation.

Energy density, the metric that determines how much work a stored charge can actually perform, tells an equally striking story. In a three-electrode half-cell configuration, the composite delivered 196 watt-hours per kilogram at 1 ampere per gram, a value that rivals some lithium-ion battery chemistries and far exceeds the 5 to 10 watt-hours per kilogram typical of commercial carbon-based supercapacitors. Electrochemical impedance spectroscopy helped explain why: the composite exhibited a charge-transfer resistance of just 0.87 ohms, an exceptionally low value indicating that ions and electrons move across the electrode-electrolyte interface with minimal obstruction. The authors attribute this to the cooperative contributions of the redox-active bismuth oxide, the conductive nanotube network, and the structurally stabilizing calcium carbonate phase working in concert.

The fabrication route is as noteworthy as the materials themselves. Rather than casting a conventional slurry onto a metal foil, the team employed an electrospinning-assisted coating approach, drawing the PVDF/DMF solution loaded with the three active components into fine fibers that deposit as a porous, high-surface-area film. Electrospinning has become a favored technique in flexible energy storage because it naturally produces interconnected fibrous networks with tunable porosity, and the group’s earlier work on MXene-PVDF fibers and flower-like MoS2 and MXene electrodes suggested that the method could be adapted to a wider palette of active materials. The present study extends that strategy to a ternary oxide-carbonate-carbon system, demonstrating that the polymer matrix can host chemically dissimilar phases without sacrificing structural integrity.

Long-term durability, however, remains the honest caveat in an otherwise impressive dataset. When the composite was cycled continuously at a demanding 30 amperes per gram for 10,000 cycles, it retained 37 percent of its initial capacitance. That retention exceeded that of the bismuth-oxide-only and nanotube-only electrodes, suggesting that the ternary architecture does buffer some of the degradation mechanisms that plague pure pseudocapacitive materials, such as volume changes during repeated redox reactions. Yet it remained below the retention of the PCC-only electrode, a reminder that high energy density and long cycle life often pull in opposite directions, and that the mechanical and chemical stresses of rapid cycling still take a measurable toll on the composite structure.

The choice of calcium carbonate as the third component is the study’s most unexpected contribution, and arguably its most interesting from a materials-design standpoint. Precipitated calcium carbonate is abundant, inexpensive, and produced at industrial scale, which makes it an attractive structural additive if it can genuinely improve electrode performance. Prior studies have explored carbonate nanoparticles in porous composite electrodes and even built asymmetric supercapacitors around nanostructured calcium carbonate, but incorporating it as a deliberate stabilizing phase within an established bismuth oxide/carbon nanotube system is a new twist. The results suggest that PCC helps preserve the mesoporous network during fabrication and cycling, preventing the collapse or agglomeration that would otherwise choke off ion transport and erode capacitance over time.

Bismuth oxide itself has been enjoying renewed attention in the energy storage community. Compared with heavier investment favorites such as ruthenium oxide or nickel cobaltites, bismuth is relatively inexpensive, environmentally benign, and offers a rich redox chemistry that can be exploited in aqueous electrolytes. Recent years have seen bismuth oxide paired with reduced graphene oxide, hierarchical porous carbon, and polyaniline, each combination attempting to solve the same twin problems of poor intrinsic conductivity and structural degradation. The Turkish team’s contribution to this crowded field is the demonstration that a three-way composite, engineered through electrospinning-assisted coating in a PVDF/DMF matrix, can achieve both high capacitance and favorable rate capability simultaneously, something that binary combinations in the same study could not match.

What comes next is clear from the authors’ own assessment: the ternary architecture provides high specific capacitance and strong rate performance, but further optimization is required to improve long-term cycling durability. Potential strategies, consistent with the broader literature, include refining the ratio of the three components, engineering protective coatings around the bismuth oxide particles, and tuning the electrospinning parameters to produce even more resilient fiber networks. If the durability gap can be closed without sacrificing the remarkable capacitance and low charge-transfer resistance already achieved, the humble trio of bismuth oxide, chalk, and carbon nanotubes could find a genuine place in the next generation of high-power energy storage devices, proving once again that in materials science, the most unglamorous ingredients sometimes deliver the most electrifying results.

Subject of Research: Ternary Bi2O3/PCC/MWCNT composite electrodes in a PVDF/DMF matrix for supercapacitor applications

Article Title: Comparative investigation of the electrochemical performance of Bi₂O₃, PCC, and MWCNT-based composites in a PVDF/DMF matrix for advanced electrode applications

Article References: Unlu, I., Dokan, F. K., Battaloglu, R., & Sahmetlioglu, E. (2026). Comparative investigation of the electrochemical performance of Bi₂O₃, PCC, and MWCNT-based composites in a PVDF/DMF matrix for advanced electrode applications. Ionics. https://doi.org/10.1007/s11581-026-07514-y

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07514-y

Keywords: supercapacitors, bismuth oxide, precipitated calcium carbonate, multi-walled carbon nanotubes, PVDF, electrospinning, ternary composite electrode, specific capacitance, energy density, electrochemical impedance spectroscopy, pseudocapacitance, mesoporous architecture

The study, published in the journal Advanced Composites and Hybrid Materials, was led by Ki-Hyun Ryu and Sungju Lee of the Korea Institute of Science and Technology, together with colleagues across several KIST research centers. Their central insight is deceptively simple: instead of trying to push ions into a densely packed nanotube fiber after the fact, why not build molecular-scale breathing room into the material from the very beginning? The answer they arrived at relies on a thermodynamically driven co-assembly process borrowed from the world of liquid crystals, a field more often associated with display screens than with supercapacitors.

To understand why the problem matters, it helps to picture what happens inside a conventional carbon nanotube fiber. Individual nanotubes, each essentially a rolled-up sheet of graphene a few nanometers wide, are drawn together into bundles, and those bundles are packed into a fiber with inter-bundle spacing measured at the molecular scale. This ultra-dense arrangement maximizes the contact between tubes, which is exactly what you want for load transfer and for electrons hopping from one tube to the next. But for electrochemical applications, the picture inverts. Ions from an electrolyte can only access the outermost surfaces of the fiber; the deep internal channels between bundles remain inaccessible, so the enormous theoretical surface area of the nanotubes goes largely unused. Materials scientists have long described this as a packing-accessibility trade-off, and it has been a persistent bottleneck in translating the extraordinary properties of individual nanotubes into practical devices.

The Korean team’s strategy attacks the problem at the molecular level using soft poly(vinyl alcohol), or PVA, chains. PVA is a hydrophilic, water-soluble polymer, and the researchers exploited its strong non-covalent adsorption onto carbon nanotube surfaces to intercalate the polymer chains directly into the nanotube bundles during fiber formation. Because the process occurs during a lyotropic liquid crystalline co-assembly stage, the rigid nanotubes retain the high axial alignment that is essential for efficient electron transport along the fiber, while the flexible polymer chains wedge themselves between the bundles and hold the channels open. The researchers describe the resulting architecture as unlocked, in the sense that the interstitial channels that would normally collapse into dense packing are instead molecularly secured at a controlled spacing.

The thermodynamics of this intercalation are worth appreciating. When long, flexible polymer chains are confined between rigid nanotubes, they lose some conformational entropy, but the strong adsorption energy between the polymer and the carbon surface compensates for that loss, driving the hybrid structure to self-assemble spontaneously. Once in place, the entropic relaxation of the soft chains, their tendency to coil and spread, effectively props open the interstitial channels without any external scaffolding, template, or post-processing step. This bottom-up approach stands in contrast to more common strategies that graft bulky functional groups onto nanotube walls or hybridize the fibers with additional active materials, both of which can disrupt the intrinsic structure of the nanotubes or add complexity and cost to manufacturing.

The benefits of the unlocked architecture extend beyond simple spacing. Carbon nanotube surfaces are inherently hydrophobic, which impedes wetting by aqueous electrolytes and further limits ion access. The intercalated PVA chains, being hydrophilic, impart wettability to the composite fiber, so electrolyte ions are not only given physical pathways into the interior but are also chemically encouraged to penetrate. In effect, the polymer performs double duty: it acts as a molecular spacer that maintains the channels, and it converts the fiber’s internal environment from one that repels electrolytes to one that welcomes them. The dormant internal volume of the fiber, previously inaccessible, becomes an active participant in electrochemical processes.

The quantitative evidence for this internal activation is striking. When the researchers measured the electrochemical performance of their composite fibers, they found an 11.2-fold enhancement in specific capacitance compared with pristine carbon nanotube fibers. Specific capacitance is a direct measure of how much charge a material can store per unit mass, and an improvement of more than an order of magnitude indicates that ions are genuinely reaching the deep core of the fiber rather than merely decorating its surface. The composite fibers also showed superior rate performance, meaning they retained much of their charge-storage capability even when charged and discharged rapidly. Rate capability is a sensitive probe of ion diffusion resistance: if ions had to fight their way through dense packing, performance would collapse at high rates. The fact that it did not confirms that the engineered channels substantially mitigate diffusion resistance throughout the fiber’s cross-section.

What makes this work particularly significant is its generality. The authors frame their methodology as a universal design paradigm for next-generation composite materials that require dynamic ion transport. Dense assemblies of one-dimensional nanomaterials are not limited to carbon nanotubes; nanowires, nanofibers, and other elongated building blocks face the same packing-accessibility dilemma whenever they are assembled into macroscopic forms. A spacing strategy that works during co-assembly, requires no complex active-material hybrids, and preserves the intrinsic structure of the constituent nanomaterials could therefore be applied far beyond the supercapacitor context in which it was demonstrated here. The approach also avoids covalent modification of the nanotubes, which is important because covalent chemistry on carbon surfaces introduces defects that degrade the electrical conductivity that makes nanotubes valuable in the first place.

The research was carried out at the Advanced Conductive Materials Research Center, the Carbon Composite Materials Research Center, and the Functional Composite Materials Research Center of the Korea Institute of Science and Technology in Wanju, Republic of Korea. It was supported by the Nano and Material Technology Development Programs through the National Research Foundation of Korea, funded by the Ministry of Science and ICT, as well as by a KIST Institutional Program. The work was published as an open-access article on 10 September 2026, making the full technical details freely available to researchers worldwide.

For a field that has spent decades chasing ways to make carbon nanotube assemblies live up to their nanoscale promise, the message of this study is refreshingly constructive. Rather than treating dense packing as an unavoidable compromise, the researchers showed that molecular-level design, using nothing more exotic than a soft polymer and the thermodynamics of liquid crystalline assembly, can unlock the hidden interior of a nanotube fiber while keeping its celebrated strength and conductivity intact. If the strategy proves as transferable as the authors suggest, the dense-but-dead interiors of one-dimensional nanomaterial assemblies may soon become some of the most valuable real estate in materials science.

Subject of Research: Liquid crystalline co-assembly of carbon nanotube and poly(vinyl alcohol) hybrid fibers to open interstitial channels for enhanced interfacial ion transport

Article Title: Bottom-up co-assembly of carbon nanotube and soft polymer hybrids: unlocking interstitial channels for enhanced interfacial ion kinetics

Article References: Ryu, K.-H., Lee, S., Lim, S.-I., Kim, S. G., Kim, S. M., Kim, N. D., Hwang, J. Y., Moon, S. Y., Yu, H., Jeong, H. S., & Kim, D.-Y. (2026). Bottom-up co-assembly of carbon nanotube and soft polymer hybrids: unlocking interstitial channels for enhanced interfacial ion kinetics. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02076-z

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02076-z

Keywords: carbon nanotubes, poly(vinyl alcohol), liquid crystals, co-assembly, nanocomposites, composite fibers, interstitial channels, ion diffusion, specific capacitance, supercapacitors, soft matter, Korea Institute of Science and Technology

The star of the study is the MXene, a family of two-dimensional carbides and nitrides first discovered by etching layered ceramics into atomically thin flakes. Unlike graphene, which is pure carbon, MXenes carry a menagerie of surface terminations, including oxygen, fluorine, and hydroxyl groups, that make them hydrophilic and electrically conductive. That combination has made them one of the most closely watched electrode materials of the past decade. Yet MXenes carry a stubborn flaw: their flat, sticky sheets love to restack, collapsing into dense layers that block the electrolyte from reaching much of the stored charge. A supercapacitor electrode, after all, works only where ions can go, and a restacked film is an ion-proof fortress.

The Indian team’s answer was to wedge polyaniline between the MXene sheets. Polyaniline, or PANI, is one of the oldest and cheapest conducting polymers, prized for its ease of synthesis and its ability to store charge through fast, reversible redox reactions. When the two materials share an electrode, each covers the other’s weaknesses. The MXene supplies a robust, metallically conductive scaffold and mechanical resilience; the polymer chains pry the sheets apart, preventing restacking, and add pseudocapacitance of their own. Field-emission scanning electron microscopy in the new work confirmed the outcome: the polymer effectively suppressed MXene restacking and generated a porous, interconnected architecture that lets ions move freely through the film.

The fabrication route is the study’s quiet revolution. Rather than growing polymers directly on the MXene surface through in-situ polymerization, grafting, or supercritical fluid processing, techniques that many earlier MXene-PANI papers have relied on, the researchers prepared a composite slurry and coated it onto a graphite substrate. Slurry coating is the same workhorse method used to mass-produce lithium-ion battery electrodes, which means the approach inherits an industrial pedigree that laboratory-only synthesis routes lack. The authors describe the method as simple, cost-effective, and scalable, and they deliberately set out to establish a correlation between the structural, morphological, and electrochemical properties of the resulting films, connecting what the material looks like to how it performs.

The electrochemical numbers are where the synergy becomes measurable. The composite electrode delivered a specific capacitance of 406 farads per gram at a current density of 0.5 amperes per gram, a figure that comfortably exceeded what the researchers measured for pristine MXene and pristine polyaniline electrodes prepared the same way. Specific capacitance measures how much charge an electrode can store per unit mass, and values above 400 farads per gram at modest current densities place the material among the competitive performers in the aqueous supercapacitor literature. Just as important, the electrode showed improved rate capability, meaning it held onto a substantial fraction of that capacitance even when charged and discharged faster, a property that matters enormously for real devices that must deliver power in bursts rather than at leisure.

Impedance measurements added a third pillar of evidence. The composite exhibited low internal resistance, which the authors attribute to the synergistic interaction between the conductive MXene layers and the PANI chains. In an electrode, internal resistance is the enemy of both power and efficiency: every ohm lost inside the material turns charging energy into waste heat and slows the delivery of current. By facilitating rapid electron transport along the metallic MXene sheets and efficient electrolyte penetration through the polymer-opened pores, the hybrid architecture attacks resistance from both directions at once, the electronic and the ionic.

Durability, the graveyard of many promising pseudocapacitive materials, is where the study delivers its most striking result. After 10,000 full charge-discharge cycles, the electrode retained 85.4 percent of its initial capacitance and maintained a coulombic efficiency of 95.1 percent. Coulombic efficiency measures how much of the charge pumped into the electrode comes back out on each cycle, and values in the mid-nineties indicate that parasitic side reactions, the slow chemical leaks that degrade electrodes and electrolytes, are being kept firmly in check. For a polymer-containing electrode, which might otherwise swell, crack, or shed material over thousands of cycles, that level of stability suggests the MXene scaffold is doing real mechanical work, anchoring the polymer chains as they repeatedly accept and release ions.

The physical chemistry behind that synergy is worth unpacking. Supercapacitors store charge in two complementary ways. Electric double-layer capacitance accumulates ions at the electrode surface, a process that is fast but limited by available area. Pseudocapacitance, by contrast, involves fast surface redox reactions in which the electrode material itself changes oxidation state, storing far more charge per unit of surface. MXenes contribute both mechanisms, thanks to their conductive sheets and their redox-active surface terminations, while polyaniline is a pseudocapacitive workhorse that shuttles between distinct protonated and deprotonated states. In the hybrid, the polymer’s redox capacity is wired directly into the MXene’s conductive network, so electrons generated in the polymer have an immediate highway out of the film, and ions arriving from the electrolyte find a porous, wetted landscape rather than a sealed stack of sheets.

Context matters for judging the advance. MXene-PANI composites have been reported before, including organ-like Ti3C2 architectures made by chemical grafting, hierarchical hybrids on carbon fibers, and self-assembled films in which polymer nanoparticles open ion-transport channels between sheets. Many of those routes, however, involve multi-step synthesis, specialized reagents, or processing conditions that complicate scale-up. The new work does not claim a record capacitance; instead, its contribution is methodological and diagnostic, demonstrating that a straightforward slurry-coating route can produce an electrode whose performance rivals composites made by far more convoluted chemistry, while explicitly mapping the link between microstructure and electrochemistry. In a field where reproducibility and manufacturability often lag behind headline numbers, that emphasis is significant.

The broader stakes are considerable. Flexible and wearable electronics, regenerative braking systems, grid buffering for renewable power, and fast-charging transport all need storage devices that tolerate high power and hundreds of thousands of shallow cycles, a niche where supercapacitors outperform batteries. Electrode materials that combine high capacitance, low resistance, and long cycle life, made by processes compatible with existing coating lines, are the raw material of that future. The VIT-AP team, supported by the university’s RGEMS grant and a Collaborative Research Scheme project from UGC-DAE CSR, has shown that one of the most celebrated material pairings in electrochemistry can be brought to life with a method simple enough to be handed to a factory. If the slurry-coated MXene-polyaniline architecture can be translated from graphite substrates in the laboratory to full devices on production lines, the humble coating step may prove to be the most consequential part of the whole supercapacitor.

Subject of Research: MXene/polyaniline composite electrodes for supercapacitor energy storage

Article Title: Facile fabrication of a MXene/PANI hybrid electrode for enhanced electrochemical performance in supercapacitors

Article References: Facile fabrication of a MXene/PANI hybrid electrode for enhanced electrochemical performance in supercapacitors. (n.d.). https://doi.org/10.1007/s11581-026-07545-5

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07545-5

Keywords: MXene, polyaniline, supercapacitor, energy storage, electrode materials, pseudocapacitance, slurry coating, electrochemistry, two-dimensional materials, cycle stability, specific capacitance, conducting polymers

Supercapacitors occupy a unique niche in the energy storage landscape. Unlike batteries, which store charge in slow chemical reactions, electrochemical double-layer capacitors, or EDLCs, store energy physically, as ions from the electrolyte accumulate on the surface of porous carbon electrodes. That mechanism delivers exceptional power density, near-instant charge and discharge, long cycle life, and outstanding efficiency. The trade-off has always been energy density, which depends critically on how much electrolyte-accessible surface the electrode offers. Activated carbon remains the workhorse material for these devices, typically delivering specific capacitances between 100 and 500 farads per gram, and its appeal is amplified by the fact that it can be made from cheap, renewable agricultural waste such as corncob, rice husk, coconut shell, and orange peels.

The catch lies in the activation step. Conventional physical activation involves heating a carbon precursor above 700 degrees Celsius in steam or carbon dioxide, which selectively gasifies carbon atoms to open and widen pores. Chemical activation with agents such as potassium hydroxide, sodium hydroxide, or phosphoric acid generally achieves higher surface areas and more uniform pore distributions, but it still demands temperatures around 800 degrees Celsius, long processing times, and substantial energy input. Both routes carry environmental and economic penalties, and both offer limited control over the final pore architecture. Any method that can achieve comparable porosity at lower temperature, in less time, and with less energy would represent a meaningful advance for sustainable electrode manufacturing.

Microwave irradiation offers exactly that possibility, and the new study exploits it elegantly. Unlike conventional furnaces that heat from the outside in through conduction, microwaves couple directly with the carbon matrix through dielectric and conductive losses, producing rapid, volumetric, and selective heating. Localized hot spots form at conductive or defect-rich regions, and in this case at the interfaces between the carbon and the potassium hydroxide activator, which itself acts as a porogen and a microwave absorption medium. The result is accelerated etching, faster diffusion of the activating agent into the carbon interior, and the formation of well-defined micro- and mesoporous networks in minutes rather than hours, all while avoiding the structural collapse that prolonged conventional heating can cause.

The raw material itself is unconventional. The team, led by Poonam Mahendia and Ritu Jangra with senior author Suman Mahendia of Kurukshetra University, burned a 250-milligram cotton wick in an earthen cup lamp filled with sesame oil, covering it with a stainless steel vessel to trap the smoke. Sesame oil is rich in polyunsaturated fatty acids, containing roughly 40 to 50 percent linoleic acid and 33 to 44 percent oleic acid. During combustion, these long-chain triglycerides decompose through cracking, dehydrogenation, aromatization, and incomplete oxidation, generating soot-like carbon particles. The oil thus serves three roles at once: it supplies the carbon skeleton, its unsaturated fatty acids promote partial aromatization into defective, turbostratic carbon domains that are far more reactive toward potassium hydroxide etching than graphitized carbon, and the incomplete combustion leaves behind oxygen-containing surface groups that improve wettability in aqueous electrolytes and may contribute additional charge storage.

The synthesis route was deliberately simple. The black powder peeled from the vessel walls was first carbonized at 400 degrees Celsius for two and a half hours under nitrogen to yield what the researchers call bare carbon, with a modest surface area of 92.5 square meters per gram and a total pore volume of 0.13 cubic centimeters per gram. That material was then mixed with potassium hydroxide in a five-to-one ratio in deionized water, stirred for 24 hours, dried into a thick paste, and subjected to microwave heating at 110 degrees Celsius in convection mode at full 1200-watt power for just five minutes. Washing with dilute hydrochloric acid and water removed residual impurities, leaving the activated carbon, designated AA, with a surface area of 686 square meters per gram and a pore volume of 0.44 cubic centimeters per gram.

Characterization confirmed the transformation at every scale. Nitrogen adsorption isotherms showed that activation shifted the material toward a type IV profile with a larger hysteresis loop, indicating a higher proportion of mesopores, the ion-transport channels that complement the micropores responsible for double-layer formation and capacitance. X-ray diffraction revealed broad, low-intensity peaks near 23 and 43 degrees, signatures of highly disordered carbon, with the activated sample showing an expanded interlayer spacing of 0.39 nanometers compared with 0.37 nanometers before activation, both well above graphite’s 0.335 nanometers. That disorder, the authors note, reflects carbon layers separated by functional groups and structural defects, which create additional active sites for charge storage. Scanning electron microscopy completed the picture, showing layer-like carbon sheets with sparse porosity before activation and a well-developed pore structure throughout the sample afterward.

The electrochemical results are where the five-minute treatment truly pays off. Cyclic voltammetry produced nearly rectangular curves characteristic of ideal double-layer behavior, with specific capacitances of 300 farads per gram for the activated material against just 18 farads per gram for the untreated carbon at 10 millivolts per second. Galvanostatic charge-discharge testing at 1 ampere per gram delivered the headline figure of 485 farads per gram, along with an energy density of 33.68 watt-hours per kilogram at a power density of 628.23 watts per kilogram in 6 molar potassium hydroxide electrolyte. Impedance spectroscopy showed a low charge-transfer resistance of 0.3 ohms, far below the 2.06 ohms of the untreated device, indicating fast charge transport and excellent electrode-electrolyte contact. Cycling stability proved equally convincing: after 5000 charge-discharge cycles at a demanding 20 amperes per gram, the device retained 84 percent of its capacitance with 100 percent coulombic efficiency.

To demonstrate practical viability, the researchers connected three identical devices in series, since aqueous electrolytes limit single cells to roughly one volt before water begins to dissociate. The stack operated stably across the 1-to-2-volt and 2-to-3-volt windows and powered a red light-emitting diode for about 65 seconds, a small but tangible proof that lamp soot from a kitchen microwave can do real electrical work. The series combination did show an increased internal resistance of 10.22 ohms, a reminder that device integration still poses engineering challenges, but the overall performance compares favorably with literature values for microwave-activated carbons, including silkworm-excrement-derived carbon at 322 farads per gram, paper-waste carbon at 237 farads per gram, and food-waste aerogels at 316 farads per gram with 16.3 watt-hours per kilogram.

What makes this work resonate beyond its numbers is the radical accessibility of the process. The precursor costs pennies, the activation step runs at 110 degrees Celsius instead of 800, and the total microwave exposure is measured in minutes, translating directly into energy and time savings over conventional thermochemical routes. As the demand for grid buffers, regenerative braking systems, and portable electronics grows, so does the incentive to find electrode materials that are cheap, abundant, and environmentally benign. Turning the soot of a sesame-oil lamp into a 485-farad-per-gram electrode suggests that the path to sustainable energy storage may sometimes run through the most humble corners of the household, one five-minute microwave pulse at a time.

Subject of Research: Microwave-assisted synthesis of activated carbon from cotton and sesame oil combustion soot for supercapacitor electrodes

Article Title: Microwave-assisted synthesis of activated carbon from aerobic combustion of cotton in sesamee oil for high performance supercapacitor

Article References: Mahendia, P., Jangra, R., Karakoti, M., Sinha, O. P., Sahoo, N. G., Srivastava, A., Rana, S., & Mahendia, S. (2026). Microwave-assisted synthesis of activated carbon from aerobic combustion of cotton in sesamee oil for high performance supercapacitor. Discover Electrochemistry, 3(1), Article 52. https://doi.org/10.1007/s44373-026-00139-w

Image Credits: AI Generated

DOI: 10.1007/s44373-026-00139-w

Keywords: activated carbon, supercapacitor, microwave-assisted activation, sesame oil, cotton soot, biomass-derived carbon, energy storage, porosity, electrochemical double-layer capacitor, potassium hydroxide activation, specific capacitance, sustainable materials

Polypyrrole, often abbreviated PPy, is one of the most tractable conducting polymers in electrochemistry. It can be grown directly onto a conductive surface by simply applying a potential to a solution of pyrrole monomers, a process known as electropolymerization or electrodeposition. The resulting film is electrically conductive, chemically stable, and stores charge through a pseudocapacitive mechanism: as the polymer is oxidized and reduced, ions from the electrolyte move in and out of the film to balance the electronic charge on the polymer backbone. This ion exchange gives polypyrrole a respectable capacitance, but pure polymer films suffer from well-known weaknesses. Their charge storage is limited by the density of accessible redox sites, and the repeated swelling and shrinking that accompanies ion insertion and removal gradually degrades the film, causing capacitance to fade over repeated cycling.

The research team, led by Hanane Khentite of Ferhat Abbas University of Sétif 1 together with colleagues at Mohamed Boudiaf University of M’sila and Mohamed El Bachir El Ibrahimi University of Bordj Bou Arréridj, addressed both weaknesses at once by incorporating nickel oxide, a transition metal oxide with its own rich pseudocapacitive chemistry, into the polymer matrix. Nickel oxide stores charge through reversible surface redox reactions involving the Ni2+/Ni3+ couple, and it is inexpensive, abundant, and environmentally benign compared with many alternative metal oxides such as ruthenium dioxide. The idea of combining metal oxides with conducting polymers is not new, but the details of how the two components are integrated often determine whether the composite outperforms its constituents or merely averages their shortcomings.

The fabrication method was deliberately straightforward. The researchers used indium tin oxide coated glass, a transparent conducting substrate, as the working electrode in an electrochemical cell. By controlling the deposition conditions, they grew a polypyrrole film in which nickel oxide particles were successfully embedded, producing what they designate as the ITO/PPy-NiO electrode. For comparison, they also prepared a pure polypyrrole film on the same substrate under analogous conditions. Electrochemical deposition has a practical advantage over many alternative synthesis routes: the film forms directly on the current collector, eliminating the need for polymer binders and conductive additives that add dead weight and interfacial resistance in conventional slurry-cast electrodes.

Before any electrochemical testing, the team subjected both films to a battery of structural and morphological characterization techniques. Fourier-transform infrared spectroscopy confirmed the chemical signatures of the polymer and the incorporated oxide. X-ray diffraction provided evidence of the crystalline nickel oxide phase within the composite. Scanning electron microscopy and atomic force microscopy revealed how the presence of nickel oxide altered the surface morphology of the films, changes that matter enormously in pseudocapacitive materials because charge storage occurs at or near surfaces where the electrolyte can reach the active material. A rougher, more porous morphology generally means more electrochemically accessible area and therefore higher capacitance.

The electrochemical results were unambiguous. Using cyclic voltammetry at a scan rate of 5 millivolts per second, the composite electrode delivered a specific capacitance of 230.22 farads per gram, while the pure polypyrrole film managed only 150.79 farads per gram under identical conditions. Galvanostatic charge-discharge measurements, which provide a more application-relevant picture of how an electrode behaves under constant current, told a consistent story: the composite achieved 214.87 farads per gram at a current density of 0.3 amperes per gram, against 138 farads per gram for the pristine polymer. In other words, adding nickel oxide boosted capacitance by roughly half, a substantial gain for a relatively modest modification of the synthesis recipe.

Perhaps the most striking result concerns durability, the perennial Achilles heel of conducting polymer electrodes. After 1,000 charge-discharge cycles, the composite electrode retained 89 percent of its initial capacitance, with a Coulombic efficiency above 95 percent, meaning that nearly every unit of charge put into the electrode during each cycle came back out. The pure polypyrrole electrode, by contrast, retained only 50 percent of its capacitance over the same number of cycles. This near-doubling of cycling stability suggests that the nickel oxide particles do more than simply add their own charge storage capacity; they appear to reinforce the polymer mechanically and electrochemically, buffering the volume changes that normally tear polypyrrole films apart during repeated ion insertion and removal.

The galvanostatic measurements also yielded energy and power density figures for the composite: an energy density of 19.1 watt-hours per kilogram at a power density of 120 watts per kilogram. The authors are careful to note that these values were derived from three-electrode measurements and are included for comparative purposes only. This is an important caveat that honest electrochemists increasingly emphasize. Three-electrode data reflect the behavior of a single electrode material in isolation, whereas real devices pair two electrodes in a full cell, and the device-level energy density is inevitably lower than the single-electrode figure suggests. Reporting such numbers with this qualification is a welcome example of restraint in a field where inflated claims have sometimes muddied the literature.

Mechanistically, the improvement can be understood as a synergy between two complementary charge storage mechanisms. The polypyrrole contributes a conductive, ion-permeable network that stores charge through doping and dedoping of its conjugated backbone, while the nickel oxide contributes high-capacity surface redox reactions. The conductive polymer can also serve as an electron highway to oxide particles that would otherwise be poorly connected, and the oxide in turn provides structural anchoring that limits the polymer’s swelling. Similar hybrid strategies have been explored with manganese dioxide, graphene, and other additives, and the present work situates nickel oxide within that broader family of conducting polymer-metal oxide composites that the same research group and others have been developing for years.

The practical implications are modest but real. Electrodeposition is a scalable, low-temperature, solution-based technique compatible with a variety of substrates, and nickel oxide is among the cheapest pseudocapacitive oxides available. An electrode that combines a 50 percent capacitance gain with dramatically improved cycling stability, achieved through a one-step electrochemical route without binders, is exactly the kind of incremental engineering advance that accumulates into commercially meaningful progress. The work, published online on 29 September 2026 in Ionics, adds to a growing body of evidence that the future of supercapacitor electrodes lies not in any single miracle material but in carefully engineered composites where a conductive polymer and a redox-active oxide each compensate for the other’s weaknesses. For grid buffering, regenerative braking, and portable electronics, where devices must deliver power in a flash and survive decades of abuse, that kind of durability-first design philosophy may prove more valuable than any headline-grabbing record.

Subject of Research: Nickel oxide-incorporated polypyrrole composite electrodes for supercapacitor energy storage

Article Title: Increased polypyrrole sheet electrochemical performance for supercapacitor applications by incorporation nickel oxide

Article References: Khentite, H., Habelhames, F., Bahloul, A., Nessark, B., Sayah, A., & Boughezal, A. (2026). Increased polypyrrole sheet electrochemical performance for supercapacitor applications by incorporation nickel oxide. Ionics. https://doi.org/10.1007/s11581-026-07546-4

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07546-4

Keywords: polypyrrole, nickel oxide, supercapacitor, electrochemical deposition, pseudocapacitance, composite electrode, cycling stability, specific capacitance, energy storage, conducting polymer, electrochemistry, Ionics

The choice of CuCo2O4 is grounded in solid electrochemical logic. As a binary transition metal oxide with a cubic spinel architecture, it hosts copper and cobalt cations on distinct lattice sites, each capable of switching between multiple oxidation states, Cu2+/Cu+ and Co3+/Co2+, during reversible Faradaic redox reactions. This rich redox chemistry underpins pseudocapacitance, the mechanism by which charge is stored through fast surface reactions rather than slow bulk diffusion. Compared with conventional cobalt oxides such as Co3O4, CuCo2O4 offers better electronic conductivity, and copper is both cheaper and less toxic than cobalt, an important consideration for any technology hoping to scale up. Yet pristine CuCo2O4 has well-known weaknesses: low surface area, a tendency for nanoparticles to clump together, sluggish ion diffusion through dense structures, and mechanical degradation as the material swells and shrinks during cycling.

The team’s solution was to marry the oxide to a porous carbon scaffold made from agricultural waste. Coconut shells were washed, dried, crushed, and carbonized at 900 degrees Celsius for four hours, yielding an activated carbon powder rich in micropores and mesopores and decorated with oxygen-containing functional groups that bond readily with metal oxide surfaces. The CuCo2O4 itself was synthesized through a sol-gel combustion route, with copper chloride and cobalt precursors chelated by citric acid, gelled, dried, and calcined at 600 degrees Celsius. The final composite was made by physically grinding equal weights of oxide and carbon in an agate mortar, a deliberately simple and low-cost procedure that could easily translate to industrial production.

Structural analysis confirmed the strategy worked at the nanoscale. X-ray diffraction showed sharp, high-intensity peaks matching the cubic spinel phase of CuCo2O4, with only a trace of CuO as a secondary impurity. When the activated carbon was added, the diffraction peaks broadened and weakened, and the average crystallite size shrank from 43.89 nanometers to 33.79 nanometers. That shrinkage matters: the disordered carbon framework physically restrains particle growth and aggregation during synthesis, leaving more electrochemically active sites exposed to the electrolyte. A broad reflection between 20 and 30 degrees in the composite pattern confirmed the amorphous, graphitic character of the biomass-derived carbon dispersed among the spinel nanocrystals.

The most striking transformation appeared in the surface chemistry. Nitrogen physisorption measurements revealed that pristine CuCo2O4 has a modest BET surface area of roughly 20 square meters per gram, with mesopores averaging 25.1 nanometers wide. The composite, by contrast, exploded to 562 square meters per gram, with an average pore width of just 1.9 nanometers and a Type I isotherm characteristic of microporous materials. In practical terms, the carbon scaffold multiplies the electrode’s ion-accessible real estate by a factor of nearly thirty, creating an interconnected network through which electrolyte ions can race rather than crawl. Infrared spectroscopy added further evidence of intimate coupling, showing new carbon-oxygen and aromatic carbon-carbon bands alongside the characteristic Co-O and Cu-O vibrations of the spinel framework.

Electrochemical testing in a three-electrode cell with 3 M potassium hydroxide electrolyte translated these structural gains into performance. Cyclic voltammetry showed broad redox peaks for both materials, but the composite enclosed a far larger current area, delivering 562.5 farads per gram at 5 millivolts per second, a 96 percent jump over the pristine oxide’s 287.5 farads per gram. Galvanostatic charge-discharge measurements were even more emphatic: at a current density of 1 ampere per gram, the composite achieved a specific capacitance of 643.75 farads per gram, against 389.06 farads per gram for CuCo2O4 alone. Even when the current was pushed fivefold to 5 amperes per gram, the composite retained 507.81 farads per gram, demonstrating the rate capability that fast-charging applications demand.

Perhaps the most revealing analysis came from Dunn’s method, which separates surface-dominated capacitive storage from diffusion-limited storage. For pristine CuCo2O4, capacitive contributions ranged from just 11 to 33 percent across the tested scan rates, meaning most of its charge was locked behind slow diffusion. The composite flipped that picture entirely, with capacitive contributions of 55 to 82 percent, confirming that the activated carbon network shifts the electrode toward fast, surface-controlled charge storage. Impedance spectroscopy reinforced the point: solution resistance fell from 8.21 ohms to 4.66 ohms, and charge-transfer resistance collapsed from 2725.45 ohms to 627.87 ohms, reflecting the porous carbon’s role in opening ion pathways and improving electron transport.

Energy and power metrics tell a similarly compelling story. The composite delivered 205.76 watt-hours per kilogram at a power density of 1797.90 watts per kilogram, and still held 162.24 watt-hours per kilogram at 8985.6 watts per kilogram. The pristine oxide managed only 124.5 watt-hours per kilogram initially and lost 42 percent of that at high power. Durability testing at 5 amperes per gram showed the composite retaining 90 percent of its capacitance after 5000 cycles, comfortably ahead of the pure oxide’s 82.5 percent. The authors attribute this resilience to the carbon matrix buffering the mechanical stresses of oxide expansion and contraction, while noting that energy densities calculated from three-electrode tests may not directly translate to full device performance.

What makes this work resonate beyond the laboratory is its sustainability angle. Coconut shells are an abundant, low-cost biomass residue across tropical regions, with high carbon yield and minimal inorganic contamination, making them an ideal feedstock for electrode-grade activated carbon. By pairing waste-derived carbon with a mixed metal oxide whose redox-active cations span multiple oxidation states, the study demonstrates that high-performance energy storage need not depend on exotic or expensive materials. Compared with a previously reported CuCo2O4/reduced graphene oxide electrode that achieved 291 farads per gram, the coconut-shell composite more than doubles that figure while sustaining 90 percent retention over five times as many cycles. As grid buffering, regenerative braking, and portable electronics all demand faster, tougher, and greener storage, this trash-to-treasure electrode offers a template worth watching.

Subject of Research: CuCo2O4/activated carbon composite electrodes for supercapacitor energy storage

Article Title: Enhanced electrochemical performance of CuCo2O4 and CuCo2O4/activated carbon composites for supercapacitor applications

Article References: Franklin, J. B., Venkatesan, J., Paul, J. F. J., Harini, S., Fathima, J. P. R., Sundaram, S. J., & Kaviyarasu, K. (2026). Enhanced electrochemical performance of CuCo2O4 and CuCo2O4/activated carbon composites for supercapacitor applications. Discover Electrochemistry, 3(1), Article 56. https://doi.org/10.1007/s44373-026-00143-0

Image Credits: AI Generated

DOI: 10.1007/s44373-026-00143-0

Keywords: supercapacitors, CuCo2O4, activated carbon, coconut shells, pseudocapacitance, spinel oxide, energy storage, biomass-derived carbon, electrode materials, specific capacitance, electrochemical impedance, sustainable materials

The logic behind the design begins with the chemistry of the two building blocks. Cobalt sulfide, or CoS, is a well-studied pseudocapacitive material: in an alkaline electrolyte it undergoes fast, reversible faradaic redox reactions that store charge at the electrode surface. Compared with metal oxides, metal sulfides conduct electricity better because sulfur atoms, with their larger atomic radius and lower electronegativity than oxygen, form weaker metal-sulfur bonds and allow electrons to delocalize more freely. But CoS has a serious flaw. During repeated cycling, its structure swells and contracts, gradually degrading the electrode. Nickel diselenide, NiSe2, brings complementary virtues: selenium conducts electricity even better than sulfur, and NiSe2 displays multivalent redox behavior with resistivity below 10 to the minus 3 ohm-centimeters, making it an exceptionally conductive host. Its weakness is poor mechanical strength. The team reasoned that fusing the two could let each material compensate for the other’s shortcomings.

The synthesis itself is disarmingly simple, a point the authors emphasize as key to commercial viability. CoS microspheres were grown hydrothermally from cobalt chloride and thiourea in two thermal steps, first at 105 degrees Celsius and then at 240 degrees Celsius. NiSe2 nanoparticles were produced by reacting nickel nitrate and selenium powder in hydrazine hydrate inside a sealed autoclave at 180 degrees Celsius for 24 hours. The two powders were then blended in ethanol, sonicated, stirred and oven-dried, a wet chemical route requiring no exotic equipment. X-ray diffraction confirmed that both crystalline phases survived intact in the composite, with sharp diffraction peaks matching standard reference cards and no detectable impurities. Raman spectroscopy told a subtler story: in the composite, the characteristic vibrational peaks of each material merged and broadened, a fingerprint of interfacial strain, lattice disorder and strong phonon scattering at the newly formed heterointerface, direct evidence that the two compounds were genuinely coupled rather than merely mixed.

Electron microscopy revealed the composite’s architecture. Pure CoS forms nest-like microspheres, while NiSe2 appears as smooth, dense cubes. In the hybrid, cube-shaped and spherical nanoparticles disperse uniformly together, creating a textured landscape rich in exposed surfaces. Energy-dispersive X-ray spectroscopy detected only cobalt, sulfur, nickel and selenium, confirming high purity. Perhaps most telling were the gas-adsorption measurements. The BET surface area climbed from 12 square meters per gram for pure CoS to 19 for NiSe2 and 28 for the composite, while pore-size analysis showed a well-developed network of mesopores concentrated between 15 and 35 nanometers. That porous architecture matters enormously in practice: it prevents the nanoparticles from clumping together, multiplies the number of electrochemically active sites, and lets hydroxide ions from the electrolyte flood into the electrode with minimal diffusion resistance.

The electrochemical payoff was dramatic. In a standard three-electrode cell filled with 2 molar potassium hydroxide, cyclic voltammetry showed that the composite electrode produced the largest current response and the biggest enclosed curve area of all three samples, with clear redox peaks arising from cobalt and nickel ions shuttling between the 2-plus and 3-plus oxidation states. Crucially, those peaks barely distorted even at high scan rates, a sign of outstanding reversibility and fast ion transport. Galvanostatic charge-discharge tests delivered the headline number: a specific capacitance of 871.4 farads per gram at 1 ampere per gram, far exceeding the individual components. The discharge curves showed a pronounced plateau at low potentials, characteristic of battery-type intercalation processes running alongside surface capacitive storage, a hybrid mechanism that the impedance data reinforced, with the composite showing the lowest solution and charge-transfer resistances of any sample.

To understand where the stored charge actually resides, the team applied Dunn’s and Trassati’s kinetic analyses to the voltammetry data. The b-values, which reveal whether charge storage is surface-dominated or diffusion-controlled, fell between 0.5 and 1 for the composite and drifted toward 1, indicating that capacitive surface reactions dominate while diffusion still contributes meaningfully. At low scan rates, ions have time to penetrate deep into the nanostructure, so diffusion-controlled storage prevails; at high rates, surface adsorption takes over. The practical implication is that the heterointerface enables both mechanisms simultaneously, letting the electrode harvest charge from its bulk and its surface alike, which is precisely the synergy the designers were aiming for.

The real test came when the researchers assembled a full asymmetric supercapacitor, pairing the CoS-NiSe2 composite as the positive electrode with activated carbon as the negative one. Electrode masses were carefully balanced using the charge-balance equation so that neither electrode limits the other. The device operated stably across a generous 1.6-volt window, free of the oxygen evolution reactions that plague aqueous devices pushed too far. It delivered a specific capacitance of 173 farads per gram at 1 ampere per gram, an energy density of 61.5 watt-hours per kilogram at a power density of 950 watts per kilogram, and sustained output at a maximum power density of 4010 watts per kilogram. For context, those energy figures approach the lower range of lithium-ion batteries while retaining the raw power and cycle life that only supercapacitors offer, and they outperform most previously reported cobalt sulfide and nickel selenide devices.

Durability, the perennial stumbling block, also held up impressively. After 5,000 charge-discharge cycles at a demanding 8 amperes per gram, the device retained 91.4 percent of its initial capacitance, with coulombic efficiency hovering around 94 percent, indicating highly reversible chemistry with few parasitic side reactions. The modest decline the authors attribute to gradual structural collapse and conductivity loss over extended cycling, familiar degradation pathways in pseudocapacitive chalcogenides, but the interfacial coupling appears to buffer the volume changes that normally destroy pure CoS electrodes. Impedance spectroscopy on the full device showed a solution resistance of just 1.7 ohms and charge-transfer resistance of 3.5 ohms, confirming that the conductive network forged at the sulfide-selenide interface carries electrons with minimal loss.

What makes this work resonate beyond the laboratory bench is its economics and its message. The entire synthesis relies on inexpensive, analytical-grade chemicals, water-based hydrothermal chemistry and a simple blending step, with no precious metals, templates or high-vacuum deposition. The authors, whose study was funded by Pakistan’s Higher Education Commission and King Saud University’s research funding program, argue that the strategy offers an economically feasible route to next-generation storage for renewable energy buffering and portable electronics. More broadly, the result underscores a growing theme in materials science: the most valuable real estate on an electrode may be the atomically thin boundary where two imperfect materials meet. By engineering that interface deliberately rather than leaving it to chance, researchers can coax out synergies, faster electron transfer, richer redox activity, and structural resilience, that neither compound achieves alone. As solar and wind power continue their intermittent march onto the grid, storage devices built on such heterointerface engineering may prove essential to keeping the lights on when the sun sets and the wind stalls.

Subject of Research: CoS-NiSe2 heterostructure electrodes for high-performance asymmetric supercapacitors

Article Title: Interfacial coupling and redox engineering in CoS-NiSe2 heterostructures for high-performance asymmetric supercapacitors

Article References: Khan, I., Arif, D., Shah, S. H., Safeen, K., Shah, M. Z. U., Alotaibi, K. M., Din, S. U., Rehan, I., Haider, F., Girma, W. M., & Safeen, A. (2026). Interfacial coupling and redox engineering in CoS-NiSe2 heterostructures for high-performance asymmetric supercapacitors. Journal of Saudi Chemical Society, 30(5), Article 72. https://doi.org/10.1007/s44442-026-00115-4

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00115-4

Keywords: supercapacitors, CoS-NiSe2, heterostructure, pseudocapacitance, energy storage, transition metal chalcogenides, hydrothermal synthesis, specific capacitance, energy density, cycling stability, electrochemistry, nanocomposites

The central problem the researchers tackled is a familiar one in battery science. Liquid electrolytes move ions quickly but bring risks of leakage, chemical reactivity and flammability. Solid polymer electrolytes are safer and mechanically robust, yet they usually conduct ions far less efficiently. To close that gap, materials scientists have been turning to biopolymers — natural, renewable macromolecules that can host salts and shuttle ions — as the backbone of solid electrolytes. Chitosan, cellulose, gelatin and starch have all been explored. Cocculus hirsutus, however, had remained essentially untouched as an ion-conducting host, despite being rich in hydroxyl, carboxyl and ether functional groups that are chemically ideal for coordinating metal ions and forming hydrogen bonds.

The recipe is deceptively simple. Fresh Cocculus hirsutus leaves were collected, cleaned, shade-dried and ground into a fine powder. Half a gram of the powder was dissolved in demineralized water at room temperature, while an equal amount of polyvinyl alcohol — a biodegradable synthetic polymer with a molecular weight of about 115,000 g/mol and 99 percent hydrolysis — was dissolved separately in distilled water at 45 °C. The two solutions were blended, stirred at 40 °C, and then spiked with magnesium chloride in amounts ranging from 0.1 to 0.5 grams. The final mixtures were cast into petri dishes and left to dry at ambient temperature for three to four days, yielding free-standing films roughly 0.087 centimeters thick that could be peeled off and handled like ordinary plastic sheets.

X-ray diffraction revealed why the blend works. Pure crystalline polymers restrict ion movement because ions must hop along rigidly ordered chains. The CH/PVA films, by contrast, showed broad diffraction peaks between 13 and 49 degrees in 2θ, indicating a mostly amorphous structure. Quantitative deconvolution of the XRD patterns showed that the best-performing sample, labeled CHM4 with 0.4 grams of magnesium chloride, had a crystallinity of only about 24 percent. The salt disrupts the alignment of polymer chains and coordinates with oxygen atoms along the backbone, carving out flexible pathways through which magnesium ions can migrate. Interestingly, adding more salt proved counterproductive: the 0.5-gram formulation showed increased crystallinity and reduced conductivity, a signature of ion aggregation and salt clustering that stiffens the polymer network and traps charge carriers.

Fourier transform infrared spectroscopy confirmed that the three components genuinely interact rather than simply coexist. A broad O–H stretching band between 3255 and 3290 cm⁻¹ shifted across the series of formulations, signaling strong hydrogen bonding within the CH/PVA framework modulated by the salt. C–H stretches near 2919–2930 cm⁻¹, C=C vibrations around 1653–1655 cm⁻¹, O–H bending between 1421 and 1433 cm⁻¹, and C–Cl stretches near 817–840 cm⁻¹ all shifted subtly with salt content, mapping out the polymer–salt complexation that underpins ion transport. These molecular fingerprints verified that magnesium ions coordinate with the oxygen-rich sites of both the biopolymer and the synthetic host, dissolving the salt into mobile charge carriers.

Electrochemical impedance spectroscopy quantified just how well the ions move. Sandwiching each film between stainless steel blocking electrodes and sweeping frequencies from 42 Hz to 1 MHz, the team extracted bulk resistance from Nyquist plots. Conductivity climbed steadily as magnesium chloride was added, peaked at the 0.4-gram composition with the minimum bulk resistance, then fell when excess salt induced ion pairing. Conductance spectra displayed the classic three-region behavior of disordered ionic conductors — electrode polarization at low frequencies, a frequency-independent plateau corresponding to DC conductivity, and dispersive behavior at high frequencies that follows Jonscher’s universal power law. Dielectric measurements and electric modulus analysis corroborated the picture, showing strong low-frequency electrode polarization and relaxation features consistent with effective ionic conduction.

The CHM4 film also behaved as expected under temperature variation. An Arrhenius plot of log conductivity against inverse temperature showed a gentle slope, indicating a low activation energy for ion migration — polymer–salt interactions and enhanced segmental motion help ions hop through the amorphous matrix as heat is applied. Differential scanning calorimetry of the optimized film identified a broad endothermic feature between 50 and 85 °C attributed to the release of absorbed moisture, a subtle transition near 222.73 °C linked to increased chain mobility under Mg²⁺ coordination, and a thermal breakdown event near 342.72 °C. That high decomposition temperature, together with the absence of sharp melting peaks, confirms a thermally robust and predominantly amorphous material suitable for demanding solid-state applications.

To prove the electrolyte could actually store energy, the researchers built a symmetric electric double-layer capacitor using two activated carbon electrodes with the CHM4 film in between. Cyclic voltammetry between 0 and 0.7 volts produced rectangular, redox-peak-free curves characteristic of purely capacitive, non-faradaic charge storage. Analysis of the current response revealed a near-perfect log–log linearity with an R² of 0.99 and a slope of 0.388, indicating a roughly balanced mix of diffusion-controlled and surface-capacitive mechanisms — about 57 percent diffusive and 43 percent capacitive at 5 mV/s. Galvanostatic charge–discharge testing delivered the headline number: a specific capacitance of 104.34 F g⁻¹ at a current density of 3 A/g, with nearly symmetric charge–discharge profiles confirming excellent reversibility. When the current was pushed to 10 A/g, the device retained about 40 percent of that capacitance, a respectable rate capability for a fully solid system.

Mechanical and safety tests rounded out the assessment. The film could be bent, folded and rolled without cracking, and its stress–strain curve showed a tensile strength of about 12 MPa at a maximum force of 8.64 N, with a strain at break of 4.39 percent — stiff enough for handling, flexible enough for conformal devices. In flame testing, the film softened, curled and charred slowly rather than igniting explosively, a delayed combustion response the authors attribute to the synergistic interaction between the biopolymer, the PVA matrix and the magnesium salt. In an era when lithium-ion fires dominate headlines, an electrolyte that resists burning while conducting ions is an appealing proposition for consumer electronics and grid storage alike.

The broader significance lies in the sustainability angle. By using a plant-derived biopolymer as the primary host, avoiding plasticizers and fillers that plague many earlier PVA-based systems, and employing an inexpensive, abundant salt, the design offers a lower environmental footprint than conventional electrolytes. Magnesium itself is far more plentiful than lithium, and its divalent charge opens possibilities for high-capacity future batteries. The authors acknowledge that conductivity still trails the best liquid systems and that further optimization is needed, but the demonstration that Cocculus hirsutus — a shrub better known in traditional medicine than in materials labs — can anchor a functional solid electrolyte is a striking reminder that next-generation energy storage may grow on vines as readily as it is synthesized in reactors. The team suggests the CH/PVA/MgCl₂ platform is a promising sustainable candidate for flexible, green supercapacitors and, with further development, magnesium-based solid-state batteries.

Subject of Research: A plant-based Cocculus hirsutus/PVA/MgCl2 solid polymer electrolyte for magnesium-ion-conducting flexible supercapacitors

Article Title: Development of novel cocculus hirsutus/PVA/Mg2+ polymer composite for advanced energy storage devices

Article References: Bakkiyalakshmi, S., Muthuvinayagam, M., Naveen, C., Rajammal, K., & Sivakumar, D. (2026). Development of novel cocculus hirsutus/PVA/Mg2+ polymer composite for advanced energy storage devices. Journal of Materials Science: Polymers, 1(1), Article 8. https://doi.org/10.1007/s44493-026-00008-3

Image Credits: AI Generated

DOI: 10.1007/s44493-026-00008-3

Keywords: Cocculus hirsutus, polyvinyl alcohol, magnesium chloride, solid polymer electrolyte, ionic conductivity, supercapacitor, biopolymer, energy storage, electrochemical impedance spectroscopy, specific capacitance, flexible electronics, green materials