The study addresses the sluggish oxygen-reduction kinetics that the authors identify as a primary bottleneck in commercializing polymer electrolyte membrane fuel cells. In their catalyst series, highly electropositive lanthanum tuned the electronic structure of platinum active sites and optimized the binding energy of oxygen intermediates. The optimized PtCoLa composition displayed higher intrinsic ORR activity than commercial Pt/C, indicating an improvement in activity at the level of the catalyst’s active sites rather than a result established solely by surface area.

Lanthanum content did not have a uniformly beneficial effect. Performance rose to an optimum and then declined as more lanthanum was incorporated. The researchers associated excessive loading with segregation of amorphous phases, which blocked active sites. This behavior accounts for the reported volcano-shaped trend: a suitable lanthanum fraction enabled the strongest performance, whereas further addition impaired the catalyst. The accessible report does not specify the optimal composition, so the chemical proportions associated with the maximum cannot be determined from the supplied evidence.

Post-mortem analyses of the optimized material indicated that structural integration of lanthanum stabilized the nanoparticles during harsh operation. Suppressed agglomeration reduced the clustering of catalyst particles, while limited active-site dissolution helped preserve the catalyst’s reactive structure. These observations provide a mechanistic explanation for the reported durability and distinguish the optimized composition’s structural stability from the loss of performance caused by excessive lanthanum and amorphous-phase segregation.

The accessible source provides the study abstract and figure placeholders but not the full numerical results. It does not report mass activity, half-wave potential, durability-test duration, degradation rate, electrode loading, comparative Pt/C values, or the composition of the optimized catalyst. Performance in a complete polymer electrolyte membrane fuel cell was also not established in the available material. Accordingly, the study supports a promising catalyst-design strategy at the electrocatalyst level, but its full performance envelope and device-level implications cannot be assessed from the supplied evidence.

Subject of Research: Lanthanum-doped PtCo intermetallic electrocatalysts for oxygen reduction in polymer electrolyte membrane fuel cells

Article Title: Investigation of lanthanum doping effects on the activity and durability of PtCo intermetallic electrocatalysts for the oxygen reduction reaction

Article References: Jung, J. Y. (2026). Investigation of lanthanum doping effects on the activity and durability of PtCo intermetallic electrocatalysts for the oxygen reduction reaction. Journal of Materials Science, 61(42), 33189-33201. https://doi.org/10.1007/s10853-026-13701-z

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13701-z

Keywords: PtCoLa nanoparticles, oxygen reduction reaction, intermetallic electrocatalysts, lanthanum doping, platinum–cobalt catalyst, fuel cells, electrocatalyst durability, electronic structure, nanoparticle agglomeration, amorphous phase segregation, Investigation, lanthanum

The research, carried out by Reineck Mhlaba of the University of Limpopo in South Africa, focuses on cobalt oxide in its spinel form, Co3O4, a material long celebrated as one of the most active non-precious-metal catalysts for carbon monoxide oxidation. Earlier work by the same author showed that pretreating cobalt oxides with hydrazine boosts their activity and selectivity in PROX at the 80 to 120 degrees Celsius window that matches fuel cell operating conditions. The catch has always been durability: cobalt oxide catalysts deactivate over time, and the moisture and carbon dioxide that inevitably accompany real reformer gas accelerate that decline. The new study asks whether a pinch of lanthanum, a rare-earth element prized for its ionic conductivity and its talent for creating oxygen vacancies, can fix those weaknesses.

The answer, according to the data, is a qualified but encouraging yes. Mhlaba prepared the parent catalyst by precipitating cobalt hydroxide from cobalt nitrate with sodium hydroxide, then loaded lanthanum at 0.5, 1.0, and 2.0 weight percent by incipient wetness impregnation. All four samples were soaked in hydrazine solution for fifteen hours and calcined in air at 350 degrees Celsius before testing. When the catalysts were fed a simulated reformate stream of 1 percent CO, 1 percent oxygen, and 50 percent hydrogen balanced in helium, the catalyst carrying 1 weight percent lanthanum clearly outperformed the rest, delivering its best activity between roughly 60 and 120 degrees Celsius and reaching complete CO conversion at 140 degrees Celsius.

Selectivity, the measure of how much of the precious oxygen goes to CO rather than to wasteful hydrogen combustion, is where the doped catalyst truly shone. The 1 weight percent lanthanum formulation maintained 100 percent selectivity toward carbon dioxide across the temperature range, meaning every oxygen molecule consumed went to destroying the poison rather than burning fuel. By contrast, the catalyst overloaded with 2 weight percent lanthanum lost performance in the crucial 60 to 120 degrees Celsius window and converted noticeably more hydrogen, about 4 percent, an outcome the author attributes to excess lanthanum blocking pores and altering the balance of active sites.

Behind that sweet spot lies a story of structural fine-tuning that the study documents with an unusually complete battery of characterization techniques. X-ray diffraction confirmed the spinel Co3O4 phase in every sample and revealed a slight shift in the diffraction peaks upon lanthanum incorporation, along with the complete absence of any separate lanthanum-containing crystalline phase. That combination suggests the lanthanum atoms are either highly dispersed on the surface or tucked into the cobalt oxide lattice, where their larger ionic radius distorts the structure. The distortion matters because, as other researchers have shown, lanthanum ions substituting at octahedral cobalt sites generate oxygen vacancies, defects that activate lattice oxygen and boost oxidation activity.

Temperature-programmed reduction experiments added a second layer of evidence. Pure Co3O4 shows two characteristic reduction peaks, at about 218 and 313 degrees Celsius, corresponding to the stepwise reduction of cobalt from the plus-three to the plus-two state and then to metallic cobalt. Doping with lanthanum shifted these features and introduced a new high-temperature reduction peak near 578 degrees Celsius, which the author interprets as evidence of a strong electronic and structural interaction between lanthanum and the cobalt oxide lattice, likely through La-Co associated species. X-ray photoelectron spectroscopy backed this up, showing shifts in the cobalt core-level binding energies after doping and an increase in the ratio of Co3+ to Co2+ species on the 1 weight percent catalyst, the very redox couple thought to govern PROX performance.

The texture of the catalysts changed too. BET measurements showed the surface area climbing from 26.8 to 35.5 square meters per gram when 1 weight percent lanthanum was added, with the adsorption isotherms retaining the H4 hysteresis loop that signals an intact mesoporous structure. Electron microscopy revealed hexagonal plate-like and cubic morphologies, with lattice fringe spacings of 0.25 and 0.48 nanometers corresponding to the (111) and (311) planes of the spinel. Thermogravimetric analysis confirmed that all the catalysts were thermally stable well beyond their calcination temperature, losing less than 1.3 percent of their mass up to 600 degrees Celsius.

Perhaps the most practically important results came from the stability tests, where the feed was deliberately fouled with the two enemies of PROX catalysts: water and carbon dioxide. When 10 percent moisture was introduced, the 1 weight percent lanthanum catalyst suffered only a slight decline in activity, a resilience the study links to the peculiar electronic structure of lanthanum. Its unfilled 4f orbitals, shielded by a filled 5s2p6 shell, suppress the hydrogen bonding that lets water molecules dissociate on the surface, limiting the formation of hydroxyl groups that would otherwise smother the active sites. XPS of the spent catalyst showed a decrease in surface hydroxyl concentration, consistent with that protective mechanism.

Carbon dioxide proved a tougher adversary. Adding 15 percent CO2 to the feed cut catalytic activity by roughly 30 percent over 21 hours on stream at 130 degrees Celsius. The spent catalyst showed no structural transformation by FTIR or SEM, but its temperature-programmed reduction profile broadened and shifted, and a new carbonate band appeared at 1480 wavenumbers in the infrared spectrum, pointing to carbonate species accumulating on the surface. The XPS data of the spent sample also revealed a drop in oxygen vacancy concentration and reoxidation of Co2+ to Co3+, sketching a picture of gradual surface chemical change rather than catastrophic structural collapse.

The author is candid about the study’s limits: the catalytic experiments were not independently repeated, and future work will add replicate runs and error bars to quantify variability. Even so, the overall message is compelling. A cheap, earth-abundant cobalt oxide, nudged with a single weight percent of lanthanum and pretreated with hydrazine, can scrub carbon monoxide from hydrogen-rich gas with perfect selectivity at fuel cell temperatures while shrugging off moisture. If the stability against carbon dioxide can be extended over the thousands of hours a commercial fuel cell demands, lanthanum-doped Co3O4 could become a serious contender to replace expensive platinum-group PROX catalysts, bringing cleaner, longer-lived hydrogen fuel cells a step closer to the pump.

Subject of Research: Lanthanum-doped cobalt oxide catalysts for the preferential oxidation of carbon monoxide in hydrogen-rich fuel cell feed streams

Article Title: Effect of La on the Structure, Selectivity and Stability of La/Co3O4 Catalysts in Preferential Oxidation of Carbon Monoxide in Hydrogen-Rich Streams

Article References: Mhlaba, R. (2026). Effect of La on the Structure, Selectivity and Stability of La/Co3O4 Catalysts in Preferential Oxidation of Carbon Monoxide in Hydrogen-Rich Streams. Catalysis Letters, 156(11), Article 305. https://doi.org/10.1007/s10562-026-05547-6

Image Credits: AI Generated

DOI: 10.1007/s10562-026-05547-6

Keywords: PROX, lanthanum doping, Co3O4, carbon monoxide oxidation, hydrogen purification, fuel cells, catalyst stability, oxygen vacancies, XPS, temperature-programmed reduction, selectivity, cobalt oxide spinel

The material belongs to a class called layered double hydroxides, or LDHs, structures best imagined as positively charged metal hydroxide sheets stacked like a deck of cards, with water and mobile anions filling the spaces between them. That architecture gives LDHs an unusually high density of electroactive sites exposed to the electrolyte, which is exactly what a pseudocapacitive electrode needs, because charge storage in these materials relies on fast, reversible redox reactions occurring at or near the surface. Nickel and cobalt have dominated the field precisely because both metals shuttle readily between oxidation states, but LDHs made from them suffer from well-known weaknesses: sheets that tend to restack and block access to active sites, moderate electrical conductivity, and structural degradation under the mechanical stress of long-term cycling.

The Indian team’s strategy was to attack those weaknesses from two directions at once. First, they chose a hydrothermal synthesis route, sealing metal precursors in an aqueous reaction medium and letting them crystallize under elevated temperature and pressure. Hydrothermal growth is prized in electrode research because it encourages the formation of well-ordered nanosheet architectures rather than tangled or amorphous precipitates. In the resulting material, scanning electron microscopy and transmission electron microscopy revealed a hierarchical nanostructure—a network of sheets arranged across multiple length scales—which the authors attribute to the controlled crystallization that the hydrothermal environment makes possible. Such hierarchical textures matter enormously in practice, since they create channels for ions to penetrate deep into the electrode rather than stalling at its outermost surface.

The second lever was the lanthanum itself. Lanthanum ions, with their large ionic radius and stable trivalent state, act as a structural and electronic modifier when incorporated into the nickel-cobalt hydroxide layers. According to the study, the presence of La3+ produced a slight increase in the interlayer spacing—the gap between the stacked hydroxide sheets—effectively propping the deck of cards open. Wider galleries mean easier access for hydroxide ions from the electrolyte, more intercalation sites during charging and discharging, and reduced sheet-to-sheet restacking that would otherwise render much of the material electrochemically dead. Rare-earth elements have been steadily gaining attention in the electrode literature for exactly this kind of role, with earlier work reporting improved capacity and lifespan when lanthanum or other rare earths were coupled with nickel-cobalt systems, including recent studies on synergistic lanthanum and scandium doping in nickel-cobalt LDHs and on lanthanum-oxide and nickel-cobalt LDH nanocomposites.

Structural confirmation came from X-ray diffraction, which verified the formation of the LDH crystalline phase through its characteristic (003) and (006) reflections—the fingerprint of a well-ordered layered lattice. The doping-related expansion of the interlayer spacing showed up as a small shift in these peaks, tying the atomic-level chemistry directly to the nanostructure. That connection between synthesis, structure, and performance is the intellectual core of the work: the authors argue that the synergistic effects of multi-metal redox properties and the structural adjustments induced by lanthanum incorporation are jointly responsible for the electrode’s behavior, rather than any single ingredient acting alone.

The electrochemical evidence followed a standard but rigorous testing regime. Cyclic voltammetry traced the redox reactions as the applied potential was swept back and forth, mapping how much charge the material could store and how quickly. Galvanostatic charge-discharge cycling measured the practical capacity under constant current, while electrochemical impedance spectroscopy probed the internal resistance and the speed of ion and electron transport within the electrode. Together, the three techniques returned the headline numbers: 390.3 mAh per gram of specific capacity, roughly 85.5 percent capacity retention over extended cycling, and 98.56 percent coulombic efficiency, meaning that almost every electron injected into the electrode during charging is recovered during discharge—a critical figure for real devices, where side reactions silently bleed away stored energy.

Crucially, the researchers did not stop at the half-cell level, which can flatter a material before it meets the demands of a complete device. They assembled an asymmetric supercapacitor, pairing the NiCoLa LDH as the battery-like faradaic electrode with a capacitive counter-electrode, allowing the device to span a wider operating voltage window than either electrode could tolerate alone. The full cell delivered a specific capacity of 34.17 mAh per gram, a specific energy of 17.08 Wh per kilogram, and a specific power of 500 W per kilogram. Those figures sit in a genuinely interesting part of the energy landscape: conventional carbon-based supercapacitors typically offer high power but only a few watt-hours per kilogram, while batteries deliver far more energy but slower charging and shorter cycle lives. An asymmetric device in the double-digit energy range with strong power delivery and rapid charging ability is precisely the hybrid profile that applications from regenerative braking to grid frequency regulation demand.

The broader context makes the result more than a one-off material triumph. The field of nickel-cobalt LDH electrodes has produced a rich catalogue of enhancement strategies in recent years: doping with sulfur, pairing LDHs with MXenes or graphene, growing heterostructures with oxides and sulfides, anchoring nanosheets onto carbon cloth or nickel foam, and assembling trimetallic layered hydroxides with hierarchical micro-flower morphologies. Each approach targets the same set of bottlenecks—conductivity, surface area, structural stability, and rate capability. The new study’s contribution is to show that lanthanum incorporation, delivered through a relatively simple and scalable hydrothermal route, can address several of those bottlenecks simultaneously without the complexity of multi-step heterostructure engineering. The hydrothermal method also avoids the need for binders in some configurations and produces crystalline material in a single vessel, factors that matter when research results must eventually translate into manufacturable electrodes.

There are, of course, the familiar caveats that attend any laboratory-scale energy-storage advance. The reported capacity retention, while respectable at about 85.5 percent, still implies measurable fading over the tested cycling window, and the path from a coin-cell or beaker-scale device to the robust, kilowatt-scale modules that real infrastructure requires involves challenges of electrode loading, electrolyte management, and thermal behavior that laboratory papers rarely address in full. The authors themselves frame the work as establishing the material as an advanced candidate for next-generation supercapacitors—a claim about promise and mechanism rather than a finished commercial technology. Still, the specific numbers reported are competitive within the current literature on LDH-based asymmetric devices, and the mechanistic story—lanthanum widening the interlayer galleries while nickel and cobalt carry the redox load—offers a clear design rule for other researchers to test and refine.

What gives the work its wider significance is the growing recognition that rare-earth chemistry may be one of the more underexploited levers in pseudocapacitor design. Lanthanum’s large size, its reluctance to participate directly in the redox chemistry, and its oxophilic character make it less a charge-storage agent than an architect: it holds the layered house open, stabilizes the lattice against the swelling and shrinking of repeated cycling, and subtly redistributes electronic density across the nickel and cobalt centers that do the electrochemical work. The Madurai team’s demonstration that this architectural role can be delivered through straightforward hydrothermal synthesis—using equipment and processes already common in materials laboratories—suggests that NiCoLa LDH and its cousins could move quickly from journal pages to prototype devices. For a world urgently needing storage that bridges the gap between instantaneous power and long-duration energy, electrodes built from carefully tailored decks of metal hydroxide cards may prove to be one of the quiet, materials-level breakthroughs on which faster progress is built.

Subject of Research: Lanthanum-doped nickel-cobalt layered double hydroxide electrodes synthesized hydrothermally for high-performance supercapacitor energy storage

Article Title: Tailoring NiCoLa layered double hydroxide via hydrothermal synthesis for superior supercapacitor performance

Article References: Prabhu, B., Karthickprabhu, S., Mahendran, M., & Deepikaa, M. (2026). Tailoring NiCoLa layered double hydroxide via hydrothermal synthesis for superior supercapacitor performance. Ionics. https://doi.org/10.1007/s11581-026-07477-0

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07477-0

Keywords: layered double hydroxide, supercapacitor, hydrothermal synthesis, lanthanum doping, nickel-cobalt electrode, pseudocapacitance, energy storage, asymmetric supercapacitor, electrochemistry, rare earth elements, specific capacity, nanosheets

Writing in the journal Ionics, Changxu Qu, Jing Wang and their colleagues at Harbin University of Commerce, Harbin Institute of Technology and Ningxia University describe an asymmetric supercapacitor built around two carefully engineered electrodes. The positive electrode is made of iron molybdate, Fe2(MoO4)3, a bimetallic oxide that has attracted attention for its rich redox chemistry but has been held back by poor electrical conductivity and structural fragility. The negative electrode is a composite of tin oxide nanoparticles and carbon nanotubes, chosen for its conductivity and fast ion transport. Together, in a flexible gel electrolyte of polyvinyl alcohol and potassium hydroxide, the two electrodes deliver an energy density of roughly 45 watt-hours per kilogram at a current density of 3 amperes per gram, with a power density of about 800 watts per kilogram. When the current is pushed to 15 amperes per gram, the device still holds around 30 watt-hours per kilogram while its power density climbs to approximately 2400 watts per kilogram.

Those numbers matter because energy density has been the stubborn bottleneck of supercapacitor design. Commercial carbon-based devices typically manage only 5 to 10 watt-hours per kilogram, an order of magnitude below lithium-ion batteries. The new device approaches the lower range of battery territory while preserving the defining supercapacitor virtues: it operates stably across a 0 to 1.6 volt window and, after 10,000 charge-discharge cycles at 5 amperes per gram, retains about 93.3 percent of its capacitance. For a device that might be cycled hundreds of times a day in a regenerative braking system or a wearable gadget, that kind of durability is as important as the headline energy figure.

The secret to the cathode’s performance lies in two intertwined strategies: defect engineering and architectural design. The researchers synthesized lanthanum-doped iron molybdate through a hydrothermal method, followed by morphology regulation, and cast the resulting active material as a slurry onto carbon cloth. Lanthanum, a rare-earth element with an ionic radius much larger than iron’s, does not simply sit quietly in the crystal lattice. Its incorporation induces local lattice distortion, and X-ray diffraction and high-resolution transmission electron microscopy revealed the structural consequences. More significantly, deconvolution of the oxygen 1s signal in X-ray photoelectron spectroscopy showed an increased proportion of oxygen vacancies and defective-oxygen species in the doped material.

Those oxygen vacancies are far more than cosmetic flaws. In transition-metal oxides, missing oxygen atoms act as donors and create pathways that make it easier for electrons to hop through the crystal, while the surrounding distorted lattice can lower the energy barrier for charge transfer at the electrode-electrolyte interface. The result, as the team’s electrochemical measurements confirmed, is a material with enhanced electrical conductivity and faster charge-transfer kinetics, precisely the properties that pristine Fe2(MoO4)3 lacks. The doping also plays a structural role: the lanthanum ions help stabilize the framework during repeated insertion and extraction of hydroxide ions, which is what allows the electrode to survive thousands of cycles without crumbling.

The second strategy is geometric. Rather than compact particles, the optimized material forms three-dimensional flower-like architectures, with petals radiating from a central core. This morphology dramatically increases the accessible surface area, reaching up to 190.58 square meters per gram after lanthanum doping, a figure comparable to some porous carbons. In an electrode, surface area is currency: every square meter offers more sites where electrolyte ions can adsorb and react. The open, petal-like structure also creates abundant ion-transport pathways, so electrolyte can penetrate deep into the electrode rather than lingering at its surface, and the architecture buffers the volume changes that accompany cycling, improving structural stability over the long term.

When tested in a three-electrode configuration, the optimized cathode, containing 0.3 weight percent lanthanum, delivered a specific capacitance of 600 farads per gram at 1 ampere per gram, an impressively high value for a bimetallic oxide cathode. Equally telling is its rate and cycling behavior: at a demanding 5 amperes per gram, the electrode retained more than 98.2 percent of its capacitance after 5000 charge-discharge cycles. That combination of high capacitance and minimal fade suggests that the defect-engineered, flower-like structure is not a laboratory curiosity but a genuinely robust electrode design.

On the other side of the cell, the team paired the cathode with a composite anode of tin oxide grown on carbon nanotubes. Tin oxide contributes additional pseudocapacitance through its own redox reactions, while the carbon nanotube network provides a conductive scaffold that keeps electrons moving and ions diffusing quickly. Electrochemical impedance measurements showed that the composite has a much lower charge-transfer resistance than pristine carbon nanotubes alone, meaning that the reactions at its surface proceed with less energy wasted as heat. In an asymmetric supercapacitor, where the positive and negative electrodes must be carefully balanced in charge capacity, having a fast, stable negative electrode is essential to unlocking the full potential of the cathode.

The word asymmetric is key to understanding why the device reaches 1.6 volts. In a conventional symmetric supercapacitor, both electrodes are made of the same carbon material, and the cell voltage is limited by how far each electrode can be polarized. An asymmetric design uses two different materials with complementary operating windows: the iron molybdate cathode works over one potential range and the tin oxide composite anode over another, so their combined window is wider than either could achieve alone. Since the energy stored scales with the square of the voltage, stretching the window from roughly 1.0 to 1.6 volts more than doubles the available energy for a given capacitance. The PVA-KOH gel electrolyte, meanwhile, makes the device inherently flexible and safe, opening the door to wearable electronics and conformal energy storage.

The work, supported by the National Natural Science Foundation of China and partner institutions, points toward a broader lesson in electrode design: the most effective energy-storage materials are rarely those with the most exotic chemistry, but those whose defects and shapes have been deliberately tuned to work with, rather than against, the physics of ion and electron transport. By injecting a trace of rare-earth dopant into a humble iron molybdate and sculpting it into a flower, the researchers transformed a conductivity-limited compound into the backbone of a device that charges fast, stores substantially, and endures. If the strategy can be scaled from carbon-cloth laboratory electrodes to industrial formats, lanthanum-doped flower-like oxides and their bimetallic cousins could become serious contenders in the race to bridge the gap between batteries and supercapacitors, a gap that has narrowed considerably with this latest advance.

Subject of Research: Defect-engineered bimetallic oxide electrodes for high-performance asymmetric supercapacitors

Article Title: La-doped flower-like Fe2(MoO4)3 cathodes coupled with SnO2/CNT anodes for high-performance asymmetric supercapacitors

Article References: Qu, C., Xing, M., Hao, T., Hao, J., Cao, J., Zhi, H., & Wang, J. (2026). La-doped flower-like Fe2(MoO4)3 cathodes coupled with SnO2/CNT anodes for high-performance asymmetric supercapacitors. Ionics. https://doi.org/10.1007/s11581-026-07458-3

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07458-3

Keywords: supercapacitors, iron molybdate, lanthanum doping, oxygen vacancies, tin oxide, carbon nanotubes, asymmetric supercapacitor, energy density, defect engineering, hydrothermal synthesis, cycling stability, energy storage