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

The target molecule in the study, Murexide, is an anionic dye with a complex aromatic structure, and it serves as a representative challenge for a much broader class of water pollutants. Synthetic dyes are notoriously difficult to remove with conventional biological treatment because their chemical stability and intense coloration persist through standard processing. Adsorption, the process by which dissolved molecules bind to the surface of a solid material, remains one of the most attractive alternatives because it is simple, scalable, and can be tuned by engineering the adsorbent itself. The question the Tunisian team set out to answer was which surface chemistry works best, and whether combining two very different materials produces something better than either alone.

The first adsorbent they tested was pure polyaniline, or PANI, a nitrogen-rich conducting polymer that has long fascinated materials scientists for its tunable electronic states and dense array of amine and imine functional groups. In its doped emeraldine state, the form confirmed in this study by physicochemical characterization, PANI carries protonated sites that can attract negatively charged dye molecules through electrostatic forces. The second adsorbent, labeled ACPO, was produced by converting raw Posidonia oceanica biomass into a hierarchically porous activated carbon. This seagrass, which forms vast underwater meadows across the Mediterranean and washes ashore in enormous quantities, has previously attracted attention as a low-cost precursor for carbon materials, including in studies targeting hexavalent chromium removal. The third material was a hybrid composite in which PANI was incorporated homogeneously throughout the porous carbon framework.

Characterization of the composite revealed something crucial about why the hybrid works. Strong interfacial interactions, mainly π–π stacking between the aromatic backbones of the polymer and the graphitic planes of the carbon, along with hydrogen bonding, ensured that the polymer phase dispersed evenly across the carbon surface rather than clumping into inaccessible aggregates. This good dispersion preserved the accessible adsorption sites of both components, meaning the composite retained the structural porosity of the activated carbon while gaining the surface functionality of the polymer. In practical terms, the hybrid material offers two complementary capture mechanisms in a single particle: the internal pore network of the carbon and the chemically active polymer coating on its surfaces.

The performance numbers tell a striking story. Pure PANI achieved a maximum adsorption capacity of 333.33 milligrams of Murexide per gram of material, while the PANI/ACPO composite reached 322.58 milligrams per gram, a nearly identical figure. The activated carbon alone, by contrast, managed only 149.25 milligrams per gram. The conclusion is unambiguous: the polymer phase dominates the uptake chemistry, and the carbon’s primary contribution is architectural rather than chemical. Yet this is precisely what makes the composite so interesting from a sustainability standpoint. By using the seagrass-derived carbon as a scaffold, the researchers can deliver PANI-level performance while consuming far less of the synthetic polymer, cutting both cost and the environmental footprint of adsorbent production.

Equilibrium modeling added another layer of insight. For both PANI and the composite, the experimental data fit the Langmuir isotherm model, which describes adsorption as a process approaching a finite monolayer of dye molecules on energetically uniform sites, with correlation coefficients above 0.96. The bare activated carbon behaved differently, following the Freundlich model with a correlation coefficient of approximately 0.966, a signature of surface heterogeneity and multilayer adsorption. This divergence makes physical sense. The raw carbon presents a patchwork of different pore sizes and surface chemistries, each binding dye with different strengths, whereas the polymer-coated materials present a more uniform population of binding sites dominated by the polymer’s functional groups.

Kinetic analysis showed that uptake over time followed the pseudo-second-order model for all three materials, indicating that the rate-limiting step involves chemisorption-like interactions between the dye and the surface rather than simple mass transfer alone. However, the researchers also found that intraparticle diffusion and boundary layer effects contributed to the overall adsorption rate, particularly for the activated carbon. This observation highlights the role of pore diffusion in mass transfer: dye molecules must physically travel through the tortuous internal network of the carbon before reaching binding sites deep within its structure. For the composite, the polymer’s presence on external and near-surface sites shortens this journey, which helps explain why the hybrid matches pure PANI despite containing less of the high-capacity polymer phase.

Thermodynamic measurements completed the mechanistic portrait. The Gibbs free energy change was negative, confirming that adsorption is spontaneous; the enthalpy change was positive, meaning the process is endothermic and actually improves at elevated temperatures; and the entropy change was positive, indicating increasing randomness at the solid–liquid interface as dye molecules are released from solution and immobilized on the surface. Taken together, these parameters point to adsorption dominated by physical interactions rather than strong chemical bond formation. The mechanistic picture that emerges is one of coexisting uptake pathways: electrostatic attraction between protonated polymer sites and the anionic dye, π–π donor–acceptor associations between aromatic moieties on the adsorbent and the dye’s ring system, hydrogen bonding, and diffusion through the porous network.

What makes this work resonate beyond the laboratory is the circular economy logic at its core. Posidonia oceanica is not a cultivated crop; it is a naturally shed biomass that accumulates on beaches in quantities large enough to create disposal problems for coastal municipalities. Converting this waste stream into a hierarchically porous activated carbon transforms a nuisance into a functional material, and pairing it with a modest loading of polyaniline yields performance comparable to the pure polymer at a fraction of the polymer cost. The authors report that the research received no specific grant funding, and they declare no competing interests, framing the work as a straightforward contribution to the growing field of biomass-derived adsorbents for wastewater remediation.

The study also arrives amid intensifying global concern about water pollution and its health consequences, with recent literature documenting human health risks from contaminated water and the challenges that conventional biological and physicochemical treatments face against persistent organic pollutants. Adsorption with sustainable, low-cost materials is increasingly viewed as a practical complement to advanced treatment trains, particularly in regions where expensive imported adsorbents are out of reach. By systematically comparing a conducting polymer, a marine-biomass carbon, and their hybrid across isotherms, kinetics, and thermodynamics, Hassen and Ben Slimane have provided a template for how such materials should be evaluated before deployment. The PANI/ACPO composite, combining structural porosity with rich surface functionality, stands out as a sustainable candidate for efficient Murexide removal, and the mechanistic framework established here should transfer readily to other anionic dyes and ionic pollutants. As Mediterranean coastlines continue to receive their annual deliveries of dead seagrass, the idea that this humble biomass could anchor next-generation water treatment technology is no longer speculative; it is now supported by quantitative, mechanistically grounded evidence.

Subject of Research: Development and comparative evaluation of polyaniline, Posidonia oceanica-derived activated carbon, and their composite as sustainable adsorbents for Murexide dye removal from water

Article Title: From marine biomass to sustainable adsorbents: comparative evaluation of polyaniline, Posidonia oceanica-derived activated carbon, and their composite for Murexide removal

Article References: Hassen, A., & Ben Slimane, A. (2026). From marine biomass to sustainable adsorbents: comparative evaluation of polyaniline, Posidonia oceanica-derived activated carbon, and their composite for Murexide removal. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-026-38260-3

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38260-3

Keywords: adsorption, polyaniline, activated carbon, Posidonia oceanica, Murexide, dye removal, wastewater treatment, marine biomass, composite materials, isotherm modeling, adsorption kinetics, water pollution

The rationale behind the design rests on the complementary strengths of its two nanomaterials. Polyaniline is prized among conducting polymers for its mechanical robustness, low cost, electrical conductivity and chemically active conjugated backbone of alternating diamine and diimine units. However, its conductivity drops markedly at neutral pH, precisely the condition under which environmental water samples are typically analysed. Quantum dots, by contrast, offer quantum confinement effects, abundant edge sites and favourable electronic properties. By marrying the two, the researchers aimed to create a synergistic nanocomposite in which the quantum dots act as electron mediators, reducing charge transfer resistance and compensating for polyaniline’s weakness at neutral pH.

Fabrication began with the aqueous synthesis of the quantum dots themselves. Gadolinium chloride was combined with 3-mercaptopropionic acid in an alkaline solution, where the deprotonated thiol groups coordinated to the rare-earth metal, a transition signalled by the solution turning from clear to white. Separate sodium borohydride reductions of tellurium and selenium powders generated the chalcogenide precursors, which were injected sequentially into the gadolinium solution, the more reactive tellurium first. After refluxing at 100 degrees Celsius for an hour under anaerobic conditions, the reaction was quenched in an ice bath and the product washed and centrifuged. The result was a water-soluble, thiol-capped quantum dot suitable for biological interfacing.

The polyaniline layer was grown directly on a glassy carbon electrode by electropolymerising aniline in hydrochloric acid over thirty cyclic voltammetry cycles, producing the thin green deposit characteristic of the emeraldine salt form. This form matters: of polyaniline’s three redox states, only the emeraldine salt is both electrically conductive and stable in air and moisture, unlike the fully oxidised pernigraniline or the fully reduced leucoemeraldine. The nanocomposite was then co-deposited from a solution containing aniline, the quantum dots and acid, with the carboxylic acid termini of the capping ligand activated by EDC and NHS chemistry to form stable amide bonds with the amine groups of the polymer.

Spectroscopic characterisation confirmed the chemistry. Fourier transform infrared spectra of the nanocomposite showed a new band at 881 wavenumbers assigned to the gadolinium-sulfur stretching vibration, alongside shifts at 2977 and 1639 wavenumbers consistent with conversion of the carboxylic acid group into an amide linkage. Raman spectroscopy of the modified electrode revealed the characteristic D and G bands of graphitic carbon, with a decreasing defect-to-graphitic ratio indicating that the polymer coating dominated over disordered carbon sites. X-ray diffraction confirmed a cubic crystal structure for the quantum dots with crystallite sizes between 10 and 32 nanometres, averaging 17 nanometres.

Imaging and scattering analyses added further detail. Scanning electron microscopy showed quantum dot nanocrystals bound along the polymer nanofibres in a well-defined distribution, and energy-dispersive X-ray spectroscopy detected carbon, oxygen, sulfur, nitrogen, tellurium and selenium, with gadolinium present only in trace amounts, a limitation the authors attribute to the detection threshold of the EDS system. Small-angle X-ray scattering revealed that the quantum dots adopt core-shell shapes while the composite takes on a dumbbell geometry, and that introducing the dots onto polyaniline actually reduced particle size, improving dispersion and preventing the agglomeration that could otherwise impair conductivity and sensing performance.

The sensing element itself is a thiolated aptamer, a short single-stranded DNA sequence that folds into a defined three-dimensional structure upon binding its target. The team compared thiolated and non-thiolated versions of the CoV-RBD-4C aptamer and found the thiolated variant superior, reaching optimal electrocatalytic performance after just seven minutes of incubation in the presence of 10 nanomolar spike glycoprotein, compared with eleven minutes for the non-thiolated version. The rapid response reflects the strong covalent attachment achieved through thiol-ene chemistry between the aptamer’s thiol group and alkene functionalities on the nanocomposite surface, which produces a well-oriented monolayer with improved accessibility and stability. Bovine serum albumin was then applied to block any remaining non-specific binding sites.

When the finished sensor was exposed to increasing concentrations of spike glycoprotein, the anodic current decreased in proportion to concentration, an inverse relationship the authors explain through the aptamer’s conformational switch. Upon binding the spike protein, the aptamer folds into its three-dimensional recognition structure, and the resulting electrostatic repulsion hinders electron transfer through the film. Using square wave voltammetry across a concentration range of 0 to 0.95 femtomolar in phosphate-buffered saline, the team obtained a linear response between 0.45 and 0.80 femtomolar, with a limit of detection of 0.04 femtomolar and a limit of quantification of 0.4 femtomolar, alongside a sensitivity of 7.55 times ten to the minus four microamperes per femtomolar.

The critical test came with real environmental samples. Effluents from two South African wastewater treatment plants, Darville and Goudkoppies, were spiked with spike glycoprotein at three concentrations spanning 0.40 to 0.80 femtomolar. The sensor achieved recoveries of 98.6 to 101.4 percent with relative standard deviations below 1.4 percent in the Darville samples, and 91.5 to 103.1 percent with deviations up to 2.5 percent at Goudkoppies, performance figures that demonstrate the device can function in the chemically complex matrix of treated wastewater rather than only in idealised buffer solutions.

The implications extend beyond the current pandemic. Wastewater-based epidemiology has relied largely on reverse transcription polymerase chain reaction, the gold standard, but that approach requires laboratory infrastructure that many low-income and rural regions lack. Because the aptasensor is portable, inexpensive and amenable to miniaturisation, the authors suggest it could serve as an alternative environmental or clinical diagnostic tool during future disease outbreaks, and potentially be adapted to other biomarkers. They note that further work should optimise the number of electropolymerisation cycles to probe stability, and test the sensor against structurally similar proteins to fully establish its selectivity and durability in the field.

Subject of Research: An electrochemical aptasensor combining polyaniline and gadolinium telluride selenide quantum dots for ultrasensitive detection of SARS-CoV-2 spike glycoprotein in wastewater

Article Title: Polyaniline metal dichalcogenide-based amplified aptasensor for SARS-CoV-2 spike glycoprotein detection in wastewater

Article References: Gazu, N. T., Fuku, X., Cabunda, Z. N., Mamba, B. B., & Feleni, U. (2026). Polyaniline metal dichalcogenide-based amplified aptasensor for SARS-CoV-2 spike glycoprotein detection in wastewater. Discover Electrochemistry, 3(1), Article 59. https://doi.org/10.1007/s44373-026-00146-x

Image Credits: AI Generated

DOI: 10.1007/s44373-026-00146-x

Keywords: aptasensor, SARS-CoV-2, spike glycoprotein, wastewater surveillance, polyaniline, quantum dots, electrochemical biosensor, nanocomposite, thiolated aptamer, gadolinium telluride selenide, femtomolar detection, waterborne epidemiology

The synthetic route is deliberately straightforward. Either m-aminophenol or m-chloroaniline, or both together at ratios ranging from 9:1 down to 1:9, is dissolved in 1 M hydrochloric acid and polymerised at 0–5 °C by the dropwise addition of ammonium persulfate, a strong oxidising agent. After five hours of stirring and an overnight rest, a dark green precipitate of the conducting salt form is recovered, washed, dried, and ground into powder. Yields for the homopolymers and copolymers all exceeded 70 percent, indicating that the oxidative polymerisation procedure is efficient and reproducible. The colour changes that accompany the reaction tell their own story: the initially colourless monomer solution turns blue as oligomeric species form and then deepens to dark green as the emeraldine salt of the conductive polymer accumulates. This autocatalytic behaviour, the study notes, is shaped by the choice of oxidant and the concentrations of both dopant and reactants.

Structural confirmation came primarily from Fourier transform infrared spectroscopy. In the homopolymers, characteristic O–H and N–H stretching peaks appear near 3230 and 3348–3315 cm⁻¹ respectively, while in the copolymers these vibrations merge into a broad band between 3196 and 3244 cm⁻¹, a signature the author attributes to weak hydrogen bonding between the hydroxyl group and nitrogen atoms along the chain. The asymmetric stretching modes of the quinoid and benzenoid rings, found at 1598 and 1495 cm⁻¹ in the homopolymers, shift to 1564 and 1477 cm⁻¹ in the copolymers, confirming the formation of a genuinely conjugated backbone in which both monomer units are incorporated. The C–Cl stretching band, located at 775 cm⁻¹ in homopolychloroaniline, shifts to 779 cm⁻¹ in the copolymers and, crucially, grows in intensity as the chloroaniline fraction of the feed increases, providing direct visual evidence that monomer composition is faithfully transferred into copolymer composition.

Ultraviolet–visible spectroscopy reinforced this picture of a tunable conjugated system. The first absorption band, arising from the π–π* transition of the benzenoid ring, appears at 283 nm for poly(m-aminophenol) and 281 nm for poly(m-chloroaniline), while the copolymers show values that shift with composition, reaching 305 nm at the highest chloroaniline loading. A second broadband near 377 nm corresponds to an n–π* transition, essentially a charge transfer from the benzenoid ring to the quinoid ring, and broad polaron bands in this region indicate significant doping, protonation, and hydrogen bonding within the polymer chain. As the chloroaniline content rises, the absorption maximum red-shifts and the vibronic fine structure sharpens, both hallmarks of an extended π-conjugated system whose electronic structure is being systematically reshaped by the electron-withdrawing chlorine substituent at the meta position.

Perhaps the most striking quantitative result concerns electrical conductivity, measured in solution at 250 ppm in dimethyl sulfoxide. Homopoly(m-aminophenol) conducts at 441.4 μS cm⁻¹, while homopoly(m-chloroaniline) manages only 341 μS cm⁻¹, the latter hampered by the meta-positioned chlorine atom, which produces a non-planar conformation, increases disorder in the backbone, and restricts electron mobility. The copolymers, however, chart a clear upward trajectory as chloroaniline content increases: from 436 μS cm⁻¹ at the 10 percent loading to 989 μS cm⁻¹ at 70 percent, and a maximum of 1277 μS cm⁻¹ at 90 percent. The explanation lies in a productive electronic partnership: electron-rich aminophenol rings sit adjacent to electron-deficient chloroaniline units, generating enhanced electron resonance and charge carriers, while the hydroxyl group promotes conjugation, hydrogen bonding, and electron delocalisation that collectively outweigh the inductive damping effect of chlorine.

Beyond qualitative band assignment, the study exploits FTIR as a genuine quantitative analytical tool. Using the C–N–C absorption near 1280 cm⁻¹ as an internal standard because it appears regardless of composition, and the 779 cm⁻¹ C–Cl band as the composition-sensitive peak, the author applied the Beer–Lambert law with a tangent baseline to calculate absorbance ratios. The ratio of the C–Cl to C–N–C intensities scales linearly with the chloroaniline fraction in the feed, passing through the origin, and the data show high accuracy and reproducibility. This quantitative approach, the paper notes, has broad practical relevance, from monitoring copolymer composition and detecting additives to tracking plastic waste recycling and microplastic pollution, and it demonstrates that infrared spectroscopy can serve as a rapid, solvent-free quality-control method for these conductive materials.

Thermal stability was assessed by thermogravimetric analysis under nitrogen at a heating rate of 10 °C per minute up to 900 °C. All samples showed a characteristic four-stage degradation profile. Initial weight loss between 22 and 100 °C, about 9.3 percent for homopolymers and 6.1 percent for copolymers, reflects the removal of trapped water and physically adsorbed molecules. A second stage between 100 and 200 °C, roughly 16.5 percent, corresponds to the loss of dopant species such as water and hydrochloric acid. The third stage, spanning 200 to 350 °C with a 20–31.5 percent loss, involves the elimination of oligomers and low-molecular-weight fractions, and the final stage from 350 to 550 °C, with a dramatic 76–80 percent decline, represents the chemical breakdown of the backbone itself, leaving a carbon-rich residue of about 20–22 percent. Encouragingly, all homopolymers and copolymers remain thermally stable up to approximately 500 °C, placing them comfortably within the operating window of most electronic and sensing applications.

Scanning electron microscopy revealed how composition sculpts surface morphology. Poly(m-aminophenol) alone displays a rough surface studded with randomly distributed spherical structures on microscopic particles. As the chloroaniline fraction increases, the morphology progressively evolves toward that of poly(m-chloroaniline), and porosity rises in step with composition. This is far from a cosmetic detail: greater porosity means more surface area and more active binding sites, which makes the copolymers attractive candidates for dye adsorption and gas sensing. Related polyaniline derivatives are already proven performers in water purification, with poly-m-chloroaniline removing anionic dyes such as indigo carmine and eosin Y at rates of 98 and 99 percent within 25 minutes, driven by hydrogen bonding, π interactions, and electrostatic attraction between the dye molecules and the amine, imine, and chlorine functional groups on the polymer surface.

The biological findings add an unexpected dimension. Tested by agar diffusion against Gram-negative E. coli and Gram-positive Staphylococcus sp., the polymers showed clear antibacterial activity that tracked with composition. Poly(m-aminophenol) proved most effective against E. coli, while poly(m-chloroaniline) was the weakest, and increasing the chloroaniline content in the copolymers reduced their activity against that organism. The mechanism, as the study and prior literature describe it, rests on the polymers’ ability to form hydrogen bonds with phosphorus- and sulfur-rich components of bacterial cells, including proteins and DNA, and on the positively charged, protonated state of polyaniline-type backbones, which bind to the negatively charged lipopolysaccharide membranes of Gram-negative bacteria. Hydrophobic phenyl segments then disrupt the membrane core, causing leakage of cellular contents, loss of membrane potential, and ultimately cell lysis, while the polymers can also promote the release of hydrogen peroxide and hydroxyl radicals that oxidise bacterial biomolecules.

Taken together, the study shows that chemical oxidative copolymerisation offers a simple yet remarkably effective lever for tailoring conductive polyaniline derivatives. By varying only the monomer feed ratio, the author produced a family of materials whose solubility, conjugation length, conductivity, porosity, and antibacterial potency all shift in predictable, composition-dependent ways. The 1:9 aminophenol-to-chloroaniline copolymer emerged as the best conductor of the series, a result that points toward applications in antistatic materials, chemical sensors, and other electrically active polymer systems where processing ease and tunable conductivity matter. The author cautions that this work focused primarily on synthesis, spectroscopic characterisation, and conductivity, and that future studies should probe how oxidant concentration, acid strength, temperature, and polymerisation time influence molecular weight, morphology, and performance. Even so, the central message is clear: mixing a hydrophilic, electron-donating monomer with a hydrophobic, electron-withdrawing one yields conductive polymers that are more soluble, more processable, and in some cases more biologically active than either parent homopolymer alone.

Subject of Research: Chemical synthesis, spectral characterisation, stability, conductivity, and antibacterial activity of poly(m-aminophenol-co-m-chloroaniline) copolymers

Article Title: Chemical synthesis, quantitative and qualitative spectral characterisation, stability, and biological activity study of some electrically conductive co -polyaniline derivatives

Article References: Ibrahim, K. (2026). Chemical synthesis, quantitative and qualitative spectral characterisation, stability, and biological activity study of some electrically conductive co-polyaniline derivatives. Results in Chemistry, 30, Article 103872. https://doi.org/10.1016/j.rechem.2026.103872

Image Credits: AI Generated

DOI: 10.1016/j.rechem.2026.103872

Keywords: polyaniline, conducting polymers, m-aminophenol, m-chloroaniline, oxidative polymerisation, FTIR spectroscopy, UV-Vis spectroscopy, electrical conductivity, thermal stability, antibacterial activity, copolymerisation, materials science

The first stage of the modification targets the fundamental chemistry of the membrane itself. The researchers synthesized poly(sodium p-styrene sulfonate), or PSS, a polymer densely decorated with negatively charged sulfonate groups, and wove it into the PVDF matrix during membrane fabrication. Rather than simply blending the two polymers, which risks the hydrophilic component washing away over time, the team used a one-pot approach combining free-radical polymerization with non-solvent induced phase separation, the standard industrial casting technique. The result is a semi-interpenetrating polymer network, in which linear PVDF chains are physically entangled with a crosslinked PSS network at the molecular level. This interlocking creates what polymer scientists call a forced compatibility effect: the two dissimilar phases cannot easily separate, component leaching is suppressed, and the sulfonate groups remain permanently anchored where they can attract water molecules.

The consequences of this structural change ripple through the entire architecture of the membrane. During phase inversion, the sulfonate groups draw water into the casting film, accelerating the exchange between solvent and non-solvent and promoting the formation of finger-like pores in the supporting layer, which replaced the sponge-like structure of the unmodified PVDF membrane. Scanning electron microscopy revealed fewer large surface defects and a far more efficient pore network for water transport. The water contact angle, a measure of surface wettability, dropped from 81.3 degrees for the pristine membrane to 63.3 degrees after the first modification. Pure water flux surged more than fivefold, from 141.54 to 737.20 liters per square meter per hour, though the protein rejection rate of 86.83 percent still fell short of the 90 percent benchmark demanded of practical ultrafiltration membranes. That shortfall set the stage for the second modification.

The team explored two distinct routes to grow a polyaniline layer on the membrane surface. In the first, the membrane was soaked in an aniline solution so that protonated monomers adsorbed electrostatically onto the negatively charged sulfonate sites, then transferred to an oxidizing solution to trigger polymerization. In the second, a custom reactor delivered monomer and oxidant simultaneously across a liquid-liquid interface at the membrane surface, enabling polymerization to proceed directly where it was wanted. Both routes exploit the same anchoring chemistry: the protonated imine nitrogen atoms of the growing polyaniline chains form ionic bonds with the sulfonate groups of PSS, reinforced by hydrogen bonding, effectively locking the functional layer in place. The films announced their presence visually, turning one membrane dark brown and the other green depending on the oxidation state of the polyaniline.

The choice between the two polymerization methods proved decisive. With adsorption followed by polymerization, aniline monomers penetrated into the membrane pores before reacting, and the polyaniline formed inside partially blocked the channels, throttling flux to 265.39 liters per square meter per hour. Synchronous polymerization, by contrast, confined the reaction largely to the surface, producing a thin, uniform and dense sieving layer that left the transport channels open. The resulting membrane, designated M3, achieved a pure water flux of 401.03 liters per square meter per hour while rejecting 99.02 percent of bovine serum albumin, a standard protein foulant. Its water contact angle fell to 42.9 degrees, and its surface carried a stronger negative charge at neutral pH than either precursor membrane, sharpening the electrostatic repulsion that keeps negatively charged proteins at bay.

Antifouling performance, the metric that ultimately determines whether a membrane survives real-world service, improved dramatically. After a cycle of protein filtration and a simple water rinse, the pristine PVDF membrane recovered only 54.30 percent of its original flux, while the dual-modified M3 membrane recovered 95.59 percent. Its irreversible fouling ratio, the portion of fouling that physical cleaning cannot remove, dropped to just 4.41 percent, compared with 45.69 percent for the unmodified control. Static adsorption experiments told the same story: the M3 membrane bound the least protein of all four samples tested. The researchers attribute this resilience to a stable hydration layer, in which hydrophilic PSS and PANI chains hold water molecules at the surface as a sacrificial barrier, combined with steric hindrance from the anchored polymer layer that physically blocks proteins from entering the pores.

The membrane also showed unexpected muscle against biological fouling, one of the most expensive problems in water treatment. In plate-counting assays, the M3 membrane inhibited 88.00 percent of Escherichia coli and 87.38 percent of Staphylococcus aureus colonies, far outperforming the modest effects of the PSS-only membrane. The mechanism, according to the study, hinges on the positively charged imino sites of polyaniline, which bind to the negatively charged bacterial cell membranes and disrupt the potential gradient across bacterial ion channels, destroying the cells. Because the polyaniline is anchored ionically rather than merely coated onto the surface, this antibacterial activity should persist through cleaning cycles rather than being lost, addressing a common failure mode of antimicrobial membrane coatings.

Chemical robustness tests reinforced the picture of a membrane built for harsh duty. After 28 days of immersion in acidic solution at pH 2, the dual-modified membrane still rejected 86.83 percent of albumin, and after 28 days in alkaline solution at pH 10, it retained 84.67 percent rejection, with flux increases far smaller than those of the unmodified control. The semi-interpenetrating network raises the thermal degradation temperature of the matrix as well, limiting the motion of PVDF chains under heat. Stability against component loss is equally important: unlike conventional blended membranes, in which hydrophilic additives gradually leach into the treated water, the interlocked PSS network and ionically bonded polyaniline layer resist dissolution, a property the authors link directly to the high and repeatable flux recovery observed across filtration cycles.

Perhaps most striking is the membrane’s performance against dye pollution. Treating simulated wastewater containing Methylene Blue and Congo Red at 10 milligrams per liter, the M3 membrane rejected 99.99 percent of both dyes, relying on a combination of surface adsorption, size exclusion, electrostatic repulsion or attraction, and steric hindrance from the PANI layer. Cationic Methylene Blue was initially captured by the negatively charged surface, forming a concentration-polarization layer that then repelled further deposition, while anionic Congo Red was largely deflected electrostatically and blocked by the aggregation of its molecules in solution. After extended filtration and cleaning, dye fluxes remained stable above 200 liters per square meter per hour, with recovery rates near 97 percent. An economic analysis estimated production costs at roughly 3 to 3.5 dollars per square meter, far below typical commercial PVDF membrane costs, suggesting that this laboratory-scale dual-modification strategy could, if it survives scale-up, offer an affordable route to treating protein-rich and dye-laden industrial wastewater.

Subject of Research: Dual hydrophilic and antibacterial modification of PVDF ultrafiltration membranes for wastewater treatment

Article Title: Dual-modified PVDF ultrafiltration membranes via semi-interpenetrating polymer network construction and PANI surface polymerization

Article References: Zhang, J., Han, Y., Wu, M., Zhang, D., Zhao, W., Shi, C., Xu, J., & Cui, H. (2026). Dual-modified PVDF ultrafiltration membranes via semi-interpenetrating polymer network construction and PANI surface polymerization. Journal of Saudi Chemical Society, 30(4), Article 48. https://doi.org/10.1007/s44442-026-00099-1

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00099-1

Keywords: PVDF, ultrafiltration membrane, semi-interpenetrating polymer network, polyaniline, poly(sodium p-styrene sulfonate), antifouling, antibacterial, dye removal, wastewater treatment, NIPS, membrane fouling, BSA rejection

Polyaniline belongs to a family of materials called conducting polymers, which behave in many respects like reactive macromolecular gels when wet. When an electric current is passed through them, their polymer chains undergo oxidation or reduction, gaining or losing electrons. This triggers the exchange of counterions and solvent molecules with the surrounding electrolyte, causing the chains to swell, shrink, relax or compact. The researchers draw a striking parallel with living cells: in both cases, electrical stimuli drive chemical reactions in macromolecular chains that produce conformational movement, ionic exchange and solvent exchange, in other words, a reversible change in the chemical composition of the entire polymer-ion-solvent system. It is precisely this biomimetic quality that makes polyaniline attractive for applications ranging from sensors and artificial muscles to supercapacitors, smart windows and drug delivery systems.

The chemical mechanism underlying the switching is formally described as an anion-driven process. In the reduced state, polyaniline chains carry sigma bonds between consecutive monomeric units, allowing free rotation and numerous conformations. Upon oxidation, radical cations form along the chain, introducing new pi bonds that restrict rotation and effectively turn the chain into a molecular motor. To maintain charge neutrality, chloride anions from the 1 M hydrochloric acid electrolyte diffuse into the polymer, and water molecules follow for osmotic balance. During reduction, the reverse occurs: protons are incorporated, and chloride ions and water are expelled. The multistep redox chemistry connects three canonical forms of the polymer, leucoemeraldine, emeraldine and pernigraniline, with anodic peaks observed at 0.30 V and 0.53 V and corresponding reduction peaks at 0.44 V and 0.078 V in the team’s cyclic voltammograms.

The central innovation of the study lies in coulovoltammetry, a technique in which the cyclic voltammogram is integrated to plot the consumed charge directly against the applied potential. The resulting closed or open loops encode an enormous amount of information. A perfectly closed loop indicates that the anodic and cathodic charges are equal, meaning only reversible redox processes are occurring. Between 0 and -0.3 V on the cathodic side, and up to 0.7 V on the anodic side, the team found just such a window of pure reversibility for polyaniline in hydrochloric acid. Beyond these limits, new irreversible processes appear, identified as hydrogen evolution on the cathodic side and overoxidation or oxygen evolution on the anodic side, whose associated charges grow exponentially with increasingly extreme potential limits.

More remarkably still, the coulovoltammogram allows the authors to separate four distinct structural faradaic processes, in line with the Electrochemically Stimulated Conformational Relaxation model developed by Toribio Otero and colleagues. Starting from the fully oxidized state, the fast reduction-shrinking stage proceeds under diffusion control of counterions leaving the swelling film. Once the shrinking chains close the gel structure at a characteristic closing potential, further reduction cannot stop but slows dramatically, because the departing anions must physically push polymer chains apart to open their exit pathways. This slow reduction-compaction stage even persists into the beginning of the subsequent anodic sweep, a phenomenon the team calls reduction electrochemical inertia, which they confirmed using chronocoulograms showing continuous faradaic charge decay. Conversely, oxidation begins with a slow relaxation process that opens the compact structure and generates free volume for incoming anions, followed by fast oxidation-swelling, and finally an oxidation inertia that continues past the anodic potential limit into the cathodic sweep.

The analysis also yielded an unexpected energetic finding. By integrating the coulovoltammetric areas, the researchers calculated the electrical energy consumed during oxidation and reduction across different potential windows. The reduction energies turned out to be almost twice the oxidation energies, revealing a pronounced charge symmetry but energy asymmetry in the reaction. The authors attribute this asymmetry to the inherently different structural processes on the two sides of the cycle, including conformational relaxation, swelling, shrinking, compaction, ion trapping and electrochemical inertia, compounded by osmotic solvent exchange. Intriguingly, they suggest this mirrors the asymmetry of reaction-driven biological functions, noting that muscles perform work during contraction but not relaxation, and that ionic channels in living systems pass ions preferentially in one direction.

Perhaps the most consequential demonstration is that polyaniline’s electrochemical reaction is self-sensing, meaning it can report on its own working conditions without any additional sensor hardware. The team derived theoretical sensing equations from the reaction kinetics and Faraday’s laws, then verified them experimentally. The charge consumed by the reversible reaction showed a clean double-logarithmic linear dependence on the scan rate, with an excellent correlation coefficient of 0.993, and the same held true when frequency was used as the electrical variable. At slower scan rates, the reaction has more time to drive deep conformational changes, exchange large numbers of ions and solvent molecules, and consume correspondingly more charge and energy; at faster rates, the polymer only partially switches. The consumed electrical energy likewise varied linearly in semi-logarithmic plots against scan rate, with distinct sensitivity slopes of -6.77 J g-1 per logarithmic unit for reduction and -2.15 for oxidation.

The same logic extended to chemical and thermal conditions. When the electrolyte concentration was varied from 1 M down to 0.075 M hydrochloric acid, the consumed charge increased in a double-logarithmic fashion with concentration, because higher concentrations provide more chemical energy for deeper oxidation and greater counterion uptake. The consumed energy per gram of polymer also rose linearly with concentration, with sensitivity slopes of 2.948 J g-1 per logarithmic unit for reduction and 0.608 for oxidation. Temperature produced analogous behaviour: as the working temperature increased, thermal energy pushed the reaction toward deeper redox states, and the charge obeyed the semilogarithmic Arrhenius-derived sensing equation, with a temperature sensitivity slope of -601.28, while consumed energy rose linearly by 0.152 J g-1 per degree Celsius for reduction and 0.061 for oxidation.

Because the sensing parameters here are simply the consumed charge and the consumed electrical energy during the reaction, any electrochemical device built on polyaniline, whether a supercapacitor electrode, an actuator, an electrochromic window or a drug delivery platform, could in principle monitor its own instantaneous operating state without separate instrumentation. The authors emphasize that this differs fundamentally from conventional chemical sensing, which aims to identify or quantify specific analytes; the goal instead is a material whose reaction is intrinsically aware of the energetic and chemical ambient in which it operates, much as biological macromolecular motors simultaneously generate actuation and sense their surroundings through the same underlying reaction.

The study represents the first systematic coulovoltammetric analysis of chemically synthesized polyaniline, extending to this polymer a methodology previously applied mainly to polypyrrole, and tackling the added complexity of polyaniline’s multistep proton-coupled redox transitions. The researchers synthesized the material by chemical oxidative polymerization of aniline with ammonium persulphate in hydrochloric acid, characterized it by FTIR spectroscopy, dielectric spectroscopy, thermogravimetric analysis and electron microscopy, and coated it onto glassy carbon electrodes for electrochemical testing with a Zennium Pro workstation. Supported by fellowships from the University Grants Commission and the Kerala State Council for Science, Technology and Environment, the work contributes both to the fundamental structural electrochemistry of conducting polymers and, the authors argue, to the development of soft, wet, reactive multifunctional biomimetic devices that could reshape soft robotics, bioelectronics and biomedicine in the years ahead.

Subject of Research: Coulovoltammetric analysis of structural electrochemistry, charge-energy asymmetry and reactive self-sensing capabilities of polyaniline

Article Title: Understanding the electrochemistry of polyaniline structural processes, charge, energy and reactive sensing capabilities through coulovoltammetry

Article References: Sidheekha, M. P., Rajan, L., Prakash, S., Shabeeba, A., & Ismail, Y. A. (2026). Understanding the electrochemistry of polyaniline structural processes, charge, energy and reactive sensing capabilities through coulovoltammetry. Discover Electrochemistry, 3(1), Article 84. https://doi.org/10.1007/s44373-026-00172-9

Image Credits: AI Generated

DOI: 10.1007/s44373-026-00172-9

Keywords: polyaniline, coulovoltammetry, conducting polymers, structural electrochemistry, redox switching, ESCR model, energy asymmetry, self-sensing materials, biomimetic devices, electrochemical sensors, charge trapping, conformational relaxation

The motivation behind the work is twofold, and each half of the problem is growing. Pharmaceutical contaminants, antibiotics chief among them, are increasingly detected in rivers, lakes, and wastewater effluents around the world, where even trace concentrations can drive the evolution of resistant bacteria. At the same time, the reigning counter electrode material in dye-sensitized solar cells—platinum—is expensive, scarce, and arguably too precious to be sprinkled across terawatt-scale photovoltaic deployments. The researchers, led by G. Hariharan of the University College of Engineering, Panruti, set out to design a single multifunctional material that could address both challenges without sacrificing performance in either role.

The team’s strategy hinged on a clever piece of synthetic architecture borrowed from the world of metal-organic frameworks, or MOFs. These crystalline scaffolds of metal ions linked by organic struts are prized for their extraordinary internal surface areas, but they are often fragile and can collapse under harsh conditions. By using a MOF as a sacrificial template, the researchers grew cobalt ferrite—CoFe2O4, a magnetic spinel oxide—inheriting the framework’s porous architecture in the process. The resulting oxide was then integrated with polyaniline, a conductive polymer well known for its ability to absorb visible light and shuttle electrical charge, producing a hybrid in which the two components are in intimate contact.

That intimate contact matters enormously, because the performance of any composite material is dictated not just by what it is made of but by how well its parts cooperate. Structural and surface analyses confirmed that the hybrid had formed successfully, with a porous morphology and close interfacial contact between the cobalt ferrite and the polymer. The numbers behind the morphology are striking: the hybrid exhibited a specific surface area of 112.7 square meters per gram, a figure that translates directly into abundant exposed active sites where photocatalytic reactions and electrochemical charge transfer can take place. Porosity, in this design, is not an aesthetic flourish—it is the engineering principle that lets light and molecules reach the material’s working surfaces.

Optical measurements revealed a second key advantage. The hybrid exhibited a reduced band gap of 1.56 electron volts, meaning it absorbs light across much of the visible spectrum rather than only the ultraviolet. In practical terms, a narrow band gap allows the material to harvest the photons that make up the bulk of sunlight, exciting electrons from the valence band into the conduction band where they can drive chemistry. When those photogenerated electrons and holes migrate to the surface, they react with water and dissolved oxygen to form reactive oxygen species—aggressive chemical intermediates such as hydroxyl radicals that attack organic pollutants and break them into smaller, less harmful fragments.

The photocatalytic results demonstrate how much the hybrid design amplifies each component. Under visible-light irradiation, the CoFe2O4/PANI composite degraded 94 percent of ciprofloxacin within 90 minutes. The bare cobalt ferrite, working alone, managed only 72 percent over the same period, while pristine polyaniline reached just 65 percent. The synergy arises because the two materials complement one another: cobalt ferrite provides robust, magnetically recoverable catalytic sites, while polyaniline extends light absorption and acts as an electron conductor that helps separate and transport the charge carriers generated by the oxide. Better charge separation means fewer electrons and holes recombining harmlessly inside the particle—and more of them available to destroy pollutant molecules.

Ciprofloxacin, a widely prescribed fluoroquinolone antibiotic, is a particularly meaningful test case. Residues of the drug persist in aquatic environments because conventional wastewater treatment plants are not designed to remove them, and their continued presence exerts selective pressure on microbial communities, accelerating the spread of antimicrobial resistance. A visible-light photocatalyst that can break the molecule down rapidly offers a route to destroying such contaminants at the source, powered by sunlight rather than by energy-intensive processes. The fact that the catalyst is built around a magnetic spinel also opens the door to easy recovery of the material from treated water, an important consideration for any technology hoping to leave the laboratory.

The second act of the material’s dual career unfolded in a dye-sensitized solar cell, a photovoltaic technology in which light is captured by dye molecules and charge is collected through a liquid electrolyte. In such cells, the counter electrode’s job is to catalyze the regeneration of the electrolyte by reducing its redox couple, and platinum has long been the benchmark for that task because of its exceptional catalytic activity. Replacing platinum with an abundant, cheap alternative is one of the field’s persistent goals. When the researchers installed their hybrid as the counter electrode, the cell achieved a power conversion efficiency of 8.53 percent—comfortably above the 6.94 percent delivered by bare CoFe2O4 and the 5.48 percent from pristine polyaniline, and approaching the 9.92 percent achieved with conventional platinum.

Stability, often the Achilles’ heel of novel electrode materials, held up well under scrutiny. The hybrid-based counter electrode retained 94.7 percent of its initial efficiency after 30 days of operation, indicating that the intimate coupling between the oxide and the polymer withstands the electrochemical environment of the cell. That durability figure matters as much as the headline efficiency, because a counter electrode that degrades quickly would simply trade one cost problem—platinum—for another: frequent replacement. The authors attribute the combination of high activity and stability to the porous morphology, which maintains electrolyte access to active sites, and to the conductive polymer network, which provides fast pathways for electrons moving into the catalytic interface.

The broader significance of the study lies in its demonstration that multifunctional materials can be engineered deliberately rather than discovered by accident. By combining a MOF-derived porous spinel with a light-harvesting conductive polymer, the researchers created a platform in which one set of properties—the narrow band gap, large surface area, and interfacial charge transfer—serves photocatalysis, while another set—electrical conductivity and catalytic activity toward the electrolyte—serves photovoltaics. As antibiotics accumulate in waterways and platinum continues to inflate the cost of emerging solar technologies, designs that extract double duty from a single, inexpensive material may prove among the most consequential advances in the race to reconcile energy production with environmental protection.

Subject of Research: A MOF-derived porous CoFe2O4/polyaniline hybrid nanocomposite for photocatalytic antibiotic degradation and platinum-free dye-sensitized solar cells.

Article Title: MOF-derived porous CoFe2O4/polyaniline hybrid nanocomposite for dual applications in solar energy conversion and antibiotic remediation

Article References: MOF-derived porous CoFe2O4/polyaniline hybrid nanocomposite for dual applications in solar energy conversion and antibiotic remediation. (n.d.). https://doi.org/10.1007/s11581-026-07524-w

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07524-w

Keywords: MOF-derived nanocomposite, cobalt ferrite, polyaniline, photocatalysis, ciprofloxacin degradation, dye-sensitized solar cells, platinum-free counter electrode, visible-light photocatalyst, water remediation, antibiotic pollution, solar energy conversion, porous materials

The central problem the team set out to solve is a familiar one in electrochemistry. Nickel oxide, a transition metal oxide, carries an exceptionally high theoretical specific capacitance, meaning that in principle each gram of the material can store a large amount of charge through fast, reversible surface redox reactions in which nickel switches between oxidation states. In practice, however, pristine NiO is a poor electrical conductor. Electrons struggle to move through the oxide bulk and reach the active sites where charge storage occurs, so much of the theoretical capacity is never realized. Electrodes made from NiO alone also tend to degrade as repeated swelling and shrinking during cycling gradually destroys their structure.

To break through this bottleneck, the researchers synthesized the ternary hybrid using a two-stage route that combines hydrothermal synthesis with mechanical grinding and a solution-assisted physical mixing method. The hydrothermal step, in which reactions proceed in a sealed vessel above the boiling point of water, is a well-established way to grow crystalline metal oxide nanostructures with controlled morphology. Mechanical grinding and solution mixing then integrate the oxide with the two organic partners, producing a composite in which each component contributes a distinct function rather than merely diluting the others.

The logic of the three-way partnership is what makes the design compelling. Nickel oxide provides the redox engine, the sites of pseudocapacitive charge storage where fast faradaic reactions occur at or near the electrode surface. Polyaniline, a conducting polymer often abbreviated PANI, supplies the electrical wiring, offering a conductive pathway that lets electrons flow efficiently between active sites and the current collector. Cellulose, the abundant biopolymer that forms the structural skeleton of plants, contributes a flexible, porous network that keeps the electrode mechanically coherent, prevents aggregation of the active particles, and opens channels through which electrolyte ions can penetrate deep into the material. In effect, the composite behaves like a well-designed building: a strong frame, efficient wiring, and open corridors all working together.

The electrochemical results reported for the optimized NiO/Cellulose/PANI electrode are striking. At a scan rate of 10 millivolts per second in cyclic voltammetry, the electrode achieved a specific capacitance of 478.45 farads per gram, a figure that places it among the competitive performers for nickel oxide-based hybrid electrodes. Cyclic voltammetry measures how much charge the electrode can store as the applied voltage is swept back and forth, and the scan rate matters: slower sweeps allow ions more time to access every pore, while faster sweeps reveal how well the material keeps up under demanding conditions. A high capacitance at a moderate scan rate suggests that the porous cellulose network and the conductive polymer are genuinely improving ion and electron transport, not just adding mass.

Durability, often the Achilles heel of pseudocapacitive materials, also proved impressive. After 6000 charge-discharge cycles, the electrode retained 98 percent of its initial capacitance. That near-total retention over thousands of cycles indicates that the hybrid architecture successfully buffers the mechanical stresses and chemical degradation that normally erode performance. The cellulose scaffold appears to act as a stabilizing matrix, holding the NiO particles in place and accommodating the volume changes that accompany repeated redox reactions, while PANI maintains continuous electrical contact even as the structure flexes.

Perhaps the most consequential numbers come from the full energy-storage assessment. The electrode delivered an energy density of 37.98 watt-hours per kilogram at a power density of 825.36 watts per kilogram. Energy density describes how much energy the device can store, the property that determines how long it can power something; power density describes how quickly that energy can be delivered, the property that determines how fast it can charge or how hard it can push. Achieving nearly 38 watt-hours per kilogram while sustaining more than 800 watts per kilogram is a notable combination, because these two metrics usually pull against each other. Designs that maximize energy often sacrifice rate capability, and vice versa. The balanced performance here suggests the hybrid electrode can handle both rapid charge-discharge cycling and substantial energy delivery, exactly the profile needed for applications ranging from regenerative braking to grid frequency regulation and portable electronics.

The sustainability angle is more than a marketing flourish. Cellulose is among the most abundant renewable materials on Earth, and incorporating it into electrode architectures reduces reliance on purely synthetic or fossil-derived components while adding functionality that synthetic binders cannot match. Previous work has shown that biomass-derived carbons and cellulose-supported metal oxide arrays can serve as flexible, free-standing electrodes, and the present study extends that principle into a ternary design where the biopolymer is an integral part of the charge-storage mechanism rather than a passive filler. The synthesis route itself, relying on hydrothermal processing and simple mechanical and solution-based mixing, avoids exotic precursors and energy-intensive fabrication steps, which matters if such materials are ever to be manufactured at scale.

The broader context of this research is a field in rapid motion. Transition metal oxides, layered double hydroxides, sulfides, conducting polymers, and biomass-derived carbons have all been pressed into service as supercapacitor electrodes, and hybrid designs that combine two or three of these classes have repeatedly outperformed single-component materials. Metal-organic framework derivatives, MXene-hydrogel composites, and photo-assisted supercapacitor architectures represent parallel frontiers. What distinguishes the NiO/Cellulose/PANI work is its explicit attempt to pair high electrochemical performance with a sustainable materials platform, addressing both the technical and environmental dimensions of the energy-storage challenge in a single design.

There remain, of course, the usual caveats that separate laboratory electrodes from commercial devices. The reported measurements were obtained under controlled conditions, and translating a promising electrode into a full supercapacitor cell requires optimizing the counter electrode, the electrolyte, the separator, and the packaging, each of which imposes its own losses. Cycle life beyond 6000 cycles, performance at elevated temperatures, and behavior under mechanical stress in flexible formats all warrant further study. Nevertheless, the combination of high specific capacitance, exceptional capacitance retention, and a strong energy-power balance achieved with renewable cellulose and a scalable synthesis route marks this ternary hybrid as a serious candidate for next-generation energy storage. As the demand for fast-charging, long-lived, and environmentally responsible storage devices accelerates, designs that reconcile performance with sustainability, like the NiO/Cellulose/PANI electrode, are likely to define the direction of the field.

Subject of Research: A ternary NiO/Cellulose/PANI hybrid electrode material for high-performance sustainable supercapacitors

Article Title: Ternary hybrid electrode of NiO/Cellulose/PANI: a sustainable platform for high-performance supercapacitors

Article References: Otaif, H. Y., Alhashem, Z. H., Sadaf, S., Ahmed, I., Alam, M. W., & Iqbal, M. (2026). Ternary hybrid electrode of NiO/Cellulose/PANI: a sustainable platform for high-performance supercapacitors. Ionics. https://doi.org/10.1007/s11581-026-07534-8

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07534-8

Keywords: supercapacitors, nickel oxide, cellulose, polyaniline, hybrid electrode, energy density, specific capacitance, pseudocapacitance, energy storage, sustainable materials, hydrothermal synthesis, electrochemistry

Hybrid solar cells of this kind sit at the intersection of two very different material worlds. Organic photovoltaics, built from polymers and small molecules, are inexpensive, lightweight and mechanically flexible, but they suffer from narrow band gaps that encourage rapid charge recombination and limit photocurrent. Inorganic semiconductors, by contrast, offer excellent charge transport and robust light absorption, though at higher fabrication cost. Combining the two promises the best of both, provided the interface between the polymer and the semiconductor can be engineered to separate and transfer photoexcited charges efficiently. PANI has long been a favorite for this role. In its doped, conductive emeraldine salt form it behaves as a p-type conductor, and acid doping shrinks its optical band gap from roughly 3.06 electron volts in the undoped emeraldine base to around 2.35 to 2.54 electron volts, making it far more useful as a light-absorbing, charge-transfer layer. Paired against n-type substrates, it forms the p-n style heterojunction at the heart of the devices in this study.

The choice of inorganic partner matters enormously. Gallium arsenide is a III-V direct-band-gap semiconductor with a gap of 1.42 electron volts, a property that allows it to absorb photons efficiently and to boast high electron mobility. Silicon, the workhorse of photovoltaics, has an indirect band gap of about 1.1 electron volts, which makes absorption less efficient per unit thickness. But the Zakho team’s earlier work had already hinted that something subtler was also at play. Previous studies by co-author Dler A. Jameel and colleagues found that PANI devices on (311)A and (311)B n-GaAs substrates outperformed those on (100) GaAs, with differences in open-circuit voltage, fill factor and rectification ratio attributable to orientation-dependent interface quality, defect densities and charge transport. The new study extends that logic into a direct GaAs-versus-silicon comparison, a combination the authors describe as previously unexamined.

The fabrication itself was deliberately simple, underscoring the practical relevance of the findings. Chemically synthesized PANI was spin-coated at 2000 revolutions per minute onto each of the three substrates, which had been cleaned with deionized water and acetone and dried under nitrogen gas. Current-voltage measurements were then performed at room temperature with a Keithley 2450 source meter, both in darkness and under illumination of 60 milliwatts per square centimeter. From the illuminated current density-voltage curves the team extracted the standard photovoltaic figures of merit: open-circuit voltage, short-circuit current density, fill factor and power conversion efficiency. From the dark measurements, analyzed with the thermionic emission model, they derived the diode parameters, including saturation current, barrier height, ideality factor, series resistance and rectification ratio.

Under illumination, the PANI/(111)B n-GaAs device led on nearly every measure. Its open-circuit voltage of 129 millivolts topped the 110 millivolts of the PANI/(100) n-Si device and the 95 millivolts of the PANI/(111) n-Si device, and its short-circuit current density of 10.8 milliamperes per square centimeter edged out 10.1 for (111) silicon and well above 7.93 for (100) silicon. Fill factors clustered tightly, at 36 percent for the GaAs device against 35 and 37 percent for the two silicon orientations. The decisive margin came in conversion efficiency: 0.83 x 10^-3 percent for the GaAs heterostructure, versus 0.59 x 10^-3 percent for PANI/(111) n-Si and 0.51 x 10^-3 percent for PANI/(100) n-Si. The team attributes the GaAs advantage primarily to its direct band gap, which generates photocarriers more efficiently than indirect-gap silicon, combined with favorable charge separation and transport at the (111)B interface.

The numbers, the authors are careful to note, remain modest compared with the best hybrid devices reported elsewhere. Open-circuit voltages of 342 millivolts on PANI/(311)B n-GaAs and 400 millivolts on PANI/n-Si have appeared in prior literature, and the low values here likely reflect higher interface recombination or differences in film quality and polymer-semiconductor interaction. But the relative rankings are the point. When illuminated performance was set against dark-rectification behavior, a striking inversion emerged: the material that made the better solar cell was not the material that made the better diode. Photovoltaic output, the study concludes, is governed chiefly by the bulk optical properties of the semiconductor, while diode quality is governed chiefly by the quality of the interface, and those two qualities do not necessarily reside in the same substrate.

Dark current-voltage analysis told the second half of the story. The PANI/(111) n-Si device posted the best diode parameters of the trio: a rectification ratio of 50.20 at plus and minus one volt, dwarfing 3.98 for PANI/(100) n-Si and 1.43 for PANI/(111)B n-GaAs, alongside the highest barrier height at 0.69 electron volts and the lowest ideality factor at 3.07. Its saturation current, 2.11 x 10^-7 amperes, was also the smallest of the three. Because an ideal diode has an ideality factor of one, all three devices deviate substantially from ideal behavior, a hallmark of organic-inorganic Schottky junctions where interface states and recombination within the polymer dominate charge transport. Even so, the silicon (111) device comes closest to the ideal, which the authors attribute to a junction with fewer recombination pathways. The (100) silicon device, by contrast, showed a saturation current roughly an order of magnitude higher than its rivals, suggesting greater carrier injection and recombination at that orientation.

Turn-on voltages added further texture. The GaAs device began conducting at the lowest bias, 0.52 volts, indicating easier carrier injection at the junction, while (100) and (111) silicon required 0.58 and 0.63 volts respectively. Series resistance followed the same pattern: 0.35 kilo-ohms for the GaAs device, helped by GaAs’s higher carrier mobility, against 0.81 and 0.37 kilo-ohms for the (100) and (111) silicon devices. Larger barrier heights, the authors note, generally correspond to fewer interface defects and reduced recombination, which is precisely what the silicon (111) interface appears to deliver under dark conditions. The comparison with earlier GaAs studies is instructive: the 0.59 electron-volt barrier on (111)B GaAs sits above the 0.45 electron volts reported for (110) GaAs but below the 0.75 and 0.79 electron volts seen on (100) and (311)B orientations, reinforcing that orientation tunes the barrier landscape in ways that are neither trivial nor predictable from band gaps alone.

The broader implication is that substrate selection in hybrid photovoltaics is a two-dimensional optimization problem. If the goal is light harvesting, the bulk optical properties of the semiconductor, here GaAs’s direct gap, dominate the outcome, and the (111)B GaAs orientation additionally promotes efficient charge separation. If the goal is a rectifying junction, say for photodetectors or diode applications, interface quality takes precedence, and silicon’s (111) plane delivers the cleanest, most rectifying PANI contact measured here. For a field searching for efficiency gains through interface engineering, molecular doping and nanostructuring, the message is that the crystallographic fingerprint of the substrate is not a detail to be controlled for; it is a design variable in its own right. As flexible, solution-processed hybrid devices edge toward real applications, the authors’ systematic comparison suggests that choosing the right crystal face could matter as much as choosing the right material.

Subject of Research: Effects of substrate type and crystallographic orientation on the photovoltaic and diode performance of PANI-based organic/inorganic hybrid solar cell devices.

Article Title: Effects of substrate type and orientation on the photovoltaic and diode performance of PANI-Based organic/inorganic hybrid devices

Article References: Tatar, H. H., & Jameel, D. A. (2026). Effects of substrate type and orientation on the photovoltaic and diode performance of PANI-Based organic/inorganic hybrid devices. Journal of Materials Science: Polymers, 1(1), Article 12. https://doi.org/10.1007/s44493-026-00012-7

Image Credits: AI Generated

DOI: 10.1007/s44493-026-00012-7

Keywords: hybrid solar cells, polyaniline, PANI, GaAs, silicon, substrate orientation, heterojunction, photovoltaics, open-circuit voltage, fill factor, barrier height, ideality factor

The study, published in the journal Discover Electrochemistry, was led by Sandeep Kurundawade and Sharanappa T. Nandibewoor of KLE Technological University in Hubballi, together with colleagues at Atria Institute of Technology in Bengaluru and J.S.S. Banashankari Arts, Commerce and S.K. Gubbi Science College in Dharwad. Their choice of modifier was polyaniline, one of the oldest and best understood conducting polymers. Polyaniline is prized in materials science for its unique p-type doping chemistry, its reversible redox transitions between the leucoemeraldine, emeraldine and pernigraniline states, and its protonic conductivity, all of which allow it to alter the electronic behavior of an electrode surface. Compared with its polymeric cousins polypyrrole and polythiophene, polyaniline also offers superior environmental resilience, an essential property for a sensor intended for repeated laboratory use.

Synthesis of the polymer followed a classical route: oxidative polymerization of aniline in 1.5 molar hydrochloric acid, initiated by the gradual, drop-wise addition of ammonium persulphate while the reaction mixture was stirred. The slow addition is not decorative; it prevents over-oxidation and promotes uniform chain growth. The reaction mixture’s shift to the characteristic dark green color of polyaniline’s emeraldine salt signaled success. The researchers then characterized the product with scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Electron microscopy revealed a cohesive network of uniformly packed spherical agglomerates, while the diffraction pattern showed a broad peak near 2θ equal to 25 degrees, a signature of the polymer’s π-π stacked aromatic framework and its mildly crystalline, emeraldine-phase structure.

The heart of the sensor is a glassy carbon electrode, a workhorse of electroanalytical chemistry with a geometric area of just 0.09 square centimeters. A 1 milligram sample of polyaniline was dispersed in dimethylformamide by sonication and drop-cast onto the polished electrode, with the deposited volume optimized at 4 microliters after testing across a 2 to 8 microliter range. To measure how much the coating enlarged the electrochemically active surface, the team employed a ferricyanide redox probe and the Randles-Sevcik equation. The bare electrode’s active area was 0.04 square centimeters; with polyaniline it grew to 0.156 square centimeters, a 4.4-fold increase that translates into a far denser network of electroactive sites and correspondingly faster charge transfer.

Impedance measurements reinforced that picture. Nyquist plots, fitted to a Randles equivalent circuit, yielded charge transfer resistance values of 17.03 ohms for the bare electrode and 11.57 ohms for the modified one, while the calculated heterogeneous charge transfer rate constants rose from 1.56 × 10⁻⁵ to 2.3 × 10⁻⁵ centimeters per second and exchange currents climbed from 1.508 × 10⁻³ to 2.219 × 10⁻³ amperes. In plain terms, the polymer film does not merely add surface area; it actively lubricates the movement of electrons between the drug molecules in solution and the electrode beneath. An immersion-time study further showed that the analytical signal peaked after 40 seconds of accumulation, beyond which the response declined, likely because the available surface had saturated or an inhibitory molecular layer had formed.

With the hardware characterized, the team turned to the electrochemistry of oxybutynin itself. Cyclic voltammetry in phosphate buffer at pH 7.4, scanned between 0.5 and 1.5 volts, produced a single anodic peak with no counterpart on the reverse scan, marking the oxidation as irreversible. On the modified electrode the peak current reached 76.7 microamperes against 42.6 microamperes on bare glassy carbon, and the peak potential shifted slightly downward from 1.191 to 1.185 volts, evidence that polyaniline lowers the overpotential and eases the oxidation. Varying the pH from 3.0 to 9.2 revealed a maximum response at 7.4, close to physiological pH, and a peak potential that tracked pH with a slope of 64 millivolts per pH unit, near the Nernstian ideal of 59, indicating equal numbers of electrons and protons in the reaction.

Scan rate studies completed the mechanistic portrait. The peak current scaled linearly with the square root of the scan rate, and a log-log analysis produced a slope of 0.3285, close to the theoretical value of 0.5 for diffusion control. Applying the Laviron equation to the relationship between peak potential and scan rate gave a transfer-coefficient-electron product of 1.14, which resolved to approximately two electrons when the standard transfer coefficient of 0.5 was assumed. Combined with the pH result, the oxidation of oxybutynin at the modified electrode is therefore a diffusion-controlled, irreversible process involving two electrons and two protons, proceeding through successive electron-transfer and deprotonation steps toward an oxidized imine-type intermediate and ultimately an amine-based product.

The analytical performance is where the sensor earns its headline. Using square-wave voltammetry, a technique prized for its ability to reject background currents, the team recorded a linear response across 0.04 to 10 micromolar oxybutynin, with a detection limit of 9.16 nanomolar and a limit of quantification of 30.5 nanomolar, calculated by the standard equations based on the regression intercept’s standard deviation. That sensitivity compares favorably with previously reported oxybutynin sensors, which the authors note have tended to be either expensive, laborious to construct, or both. Selectivity testing with 100-fold excesses of citric acid, gum acacia, D-glucose, dopamine, L-ascorbic acid, sucrose, and common inorganic salts produced peak potential shifts all below the 2 percent tolerance limit, confirming the sensor’s robustness in messy real-world matrices.

The practical demonstrations may prove the most consequential part of the work. Pulverized commercial 5 milligram tablets, dissolved and diluted into the linear range, yielded recoveries in excellent agreement with the label claim, opening the door to routine pharmaceutical quality control. Human urine diluted 100-fold and spiked with known drug concentrations, along with tap water, Krishna River water from Belagavi in Karnataka, and RO-purified water, were all analyzed with acceptable recoveries, extending the sensor’s reach into pharmacokinetic monitoring and environmental surveillance of pharmaceutical contamination. Stability testing showed consistent within-day signals and retention of a high percentage of the initial response after 15 days of storage in a sealed container. Taken together, the results suggest that a coating of a cheap, easily synthesized conducting polymer can transform a routine glassy carbon electrode into a precision instrument, one well suited to clinical laboratories, quality control departments, and environmental monitoring programs that have historically been priced out of high-sensitivity drug analysis.

Subject of Research: Ultrasensitive electrochemical detection of the drug oxybutynin hydrochloride using a polyaniline-modified glassy carbon electrode sensor

Article Title: Ultrasensitive electrochemical detection of oxybutynin hydrochloride using polyaniline modified sensor

Article References: Kurundawade, S., Megalamani, M. B., Naik, K., Yaraguppi, D. A., & Nandibewoor, S. T. (2026). Ultrasensitive electrochemical detection of oxybutynin hydrochloride using polyaniline modified sensor. Discover Electrochemistry, 3(1), Article 73. https://doi.org/10.1007/s44373-026-00161-y

Image Credits: AI Generated

DOI: 10.1007/s44373-026-00161-y

Keywords: oxybutynin hydrochloride, polyaniline, electrochemical sensor, glassy carbon electrode, square-wave voltammetry, cyclic voltammetry, overactive bladder, pharmaceutical analysis, detection limit, conducting polymer, electrocatalysis, pharmacokinetics