Two-dimensional materials have captivated physicists and engineers ever since graphene was first isolated, but the field has long faced a fundamental dilemma. Graphene itself is a superb conductor, yet it lacks a bandgap, the energy barrier that separates occupied from unoccupied electronic states and makes a material useful as a semiconductor. Hexagonal boron nitride, at the other extreme, is a wide-gap insulator. Sandwiching carbon between boron and nitrogen in a single atomic plane offers a tantalizing middle ground: a lattice built entirely from light elements that could, in principle, combine the robustness of boron nitride with semiconducting behavior suitable for transistors, photodetectors, and solar cells. The new study adds a fresh entry to this growing family of borocarbonitride compounds and subjects it to one of the most demanding tests a two-dimensional material can face: sustained mechanical stretching.

The researchers began by evaluating whether the proposed BCN lattice could exist at all. Stability is the perennial Achilles heel of hypothetical two-dimensional crystals, many of which look beautiful on paper but fall apart the moment their atomic vibrations are examined. To probe this, the team performed phonon analysis, a technique that calculates the full spectrum of vibrational modes in the crystal. If any of these modes have imaginary frequencies, the lattice is dynamically unstable and will spontaneously distort or disintegrate. The BCN monolayer passed this test convincingly, remaining dynamically stable not only in its pristine form but across a wide range of applied biaxial tensile strain. That resilience matters enormously for practical applications, because any real device built on a flexible substrate will subject its active layer to mechanical stress, and a material that cannot survive deformation is of little use in flexible electronics.

In its unstrained state, the pristine BCN monolayer exhibits a direct bandgap of approximately two electronvolts. A direct bandgap means that an electron dropping from the conduction band to the valence band can emit a photon without needing a change in momentum, which is precisely the property that makes materials like gallium arsenide valuable for LEDs and lasers. A gap of roughly two electronvolts places the material in the visible-light range, meaning it can absorb and potentially emit photons in the portion of the spectrum most relevant to human vision and to solar energy conversion. This combination of a direct gap and an all-light-element composition is rare, and it immediately positions the monolayer as a candidate for ultrathin, lightweight optoelectronic components.

The most striking results, however, emerged when the researchers applied biaxial tensile strain, uniformly stretching the lattice in both in-plane directions. The bandgap proved highly sensitive to this deformation, decreasing substantially as the strain increased. This behavior follows a well-established principle in semiconductor physics: stretching a lattice weakens and lengthens the bonds between atoms, which alters the overlap of their electronic orbitals and shifts the energies of the band edges. In many two-dimensional semiconductors, including the widely studied molybdenum disulfide, strain has been shown to modify the gap by hundreds of millielectronvolts. What makes the new BCN monolayer notable is the magnitude of the effect combined with the material’s demonstrated stability under the same conditions, meaning the tuning window can actually be exploited rather than merely observed before the crystal fails.

The optical consequences of this strain sensitivity are equally significant. The team calculated the material’s absorption spectrum and found it to be highly anisotropic, meaning it absorbs light differently depending on the polarization direction relative to the crystal axes. Anisotropic absorption is a valuable property for polarization-sensitive photodetectors, which can distinguish the orientation of incoming light and are used in imaging, sensing, and communications technologies. The prominent absorption peaks in the spectrum shifted to longer wavelengths, a redshift, as tensile strain increased, tracking the narrowing of the electronic bandgap. Because the gap defines the minimum photon energy the material can absorb, stretching the lattice effectively broadens the range of low-energy photons it can capture, pulling previously invisible parts of the spectrum into play.

Perhaps the most application-relevant finding concerns the near-infrared and visible regions of the spectrum. The calculations showed that light absorption in these bands, which are the workhorse ranges for photovoltaics, imaging, and telecommunications, can be effectively enhanced by applying tensile strain. In practical terms, a thin film of this material could be made a better solar absorber or a more sensitive infrared detector simply by stretching it, without any chemical doping or compositional change. Because strain can be applied dynamically, through flexible substrates, piezoelectric actuators, or patterned substrate topography, this opens the possibility of devices whose spectral response is actively adjustable in operation, a degree of freedom that conventional bulk semiconductors cannot offer.

The study also examined excitons, the bound pairs of photoexcited electrons and holes that form when light is absorbed in a semiconductor. In two-dimensional materials, reduced dielectric screening makes excitons exceptionally tightly bound, which is scientifically fascinating but technologically problematic: an exciton that will not separate cannot contribute its charges to a photocurrent. The researchers found that the exciton binding energy in the BCN monolayer is largely reduced as tensile strain increases. Weaker exciton binding facilitates the effective spatial separation of photoexcited electrons and holes, allowing the charge carriers to escape their mutual attraction and be collected as current. For photovoltaic and photodetector applications, this strain-induced reduction in binding energy could translate directly into improved conversion efficiency and faster response times.

Methodologically, the work stands out for its rigor. Rather than relying on standard density functional theory alone, which notoriously underestimates bandgaps and neglects excitonic effects, the team employed many-body perturbation theory in the GW and Bethe-Salpeter framework, the gold standard for predicting the excited-state properties of low-dimensional materials. They combined the QUANTUM ESPRESSO simulation suite with the Yambo code for excited-state calculations, using PBE exchange-correlation functionals and optimized norm-conserving pseudopotentials from the PseudoDojo database. This level of theoretical treatment is essential for obtaining trustworthy optical spectra and exciton energies, and it lends considerable weight to the quantitative predictions about strain tuning.

The broader significance of the study lies in its demonstration that light-element two-dimensional materials deserve the same strain-engineering attention that has been lavished on transition metal dichalcogenides. The authors frame their findings as both the discovery of a new member of the light-elemental two-dimensional family and an emphasis on its potential in strain-engineered optoelectronic devices. The work was supported by the National Natural Science Foundation of China and Jiangsu University of Science and Technology. As experimentalists continue to synthesize increasingly exotic borocarbonitride phases, from graphitic BCx compounds to hexagonal BC2N films grown by chemical vapor deposition, computational studies like this one serve as a map, pointing synthetic chemists toward the structures most likely to survive the journey from theory to working devices, and toward the mechanical tricks that could unlock their full optical potential.

Subject of Research: Strain-dependent stability and electro-optical properties of a two-dimensional boron-carbon-nitride monolayer

Article Title: Impact of biaxial tensile strain on stability and electro-optical properties of new B–C–N hybrid monolayer

Article References: Dong, Y., Shu, H., & Xu, H. (2026). Impact of biaxial tensile strain on stability and electro-optical properties of new B–C–N hybrid monolayer. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13900-8

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13900-8

Keywords: BCN monolayer, two-dimensional materials, biaxial tensile strain, bandgap engineering, first-principles calculations, many-body effects, exciton binding energy, optical absorption, strain engineering, optoelectronics, phonon stability, near-infrared

The research, led by Tiantian Qiao and Sainan Zhou of Liaoning University together with Xiaoqing Lu and Yongqing Li of the China University of Petroleum, focuses on C12N8, a porous single-layer carbon nitride framework. Using density functional theory calculations paired with grand canonical Monte Carlo simulations, the team systematically explored what happens when scandium atoms are incorporated into the lattice and when the sheet is stretched under tensile strain. Their central finding is that the two modification strategies play fundamentally different roles: doping is the dominant lever for performance, while strain acts as a secondary, double-edged adjustment.

The chemistry behind the improvement is electrostatic. When a scandium atom substitutes into the C12N8 framework, it behaves as a strong cationic center, withdrawing electron density from its surroundings and dramatically increasing the polarity of the nanosheet. Carbon dioxide, with its linear structure and pronounced quadrupole moment, is highly sensitive to such electric field gradients. The doped scandium sites become primary adsorption anchors, gripping CO2 molecules far more tightly than the pristine carbon nitride ever could. Nitrogen and methane, which lack the same charge distribution, feel a much weaker pull, and that asymmetry is what produces the material’s remarkable selectivity.

The numbers are striking. Under dry gas conditions at ambient temperature, unstrained Sc-doped C12N8 achieves a CO2/N2 selectivity of 369 and a CO2/CH4 selectivity of 468 — figures that place it among the best-performing adsorbents modeled to date for these industrially critical separations. Flue gas from power plants is dominated by nitrogen, and natural gas upgrading hinges on stripping CO2 from methane, so a material that discriminates this strongly against both contaminants addresses two of the largest separation problems in the energy economy simultaneously.

Capacity tells a complementary story. When the Sc-doped nanosheet is stretched by five percent, the simulated CO2 uptake reaches 8.19 millimoles per gram at 298 kelvin and 1 bar, conditions close to those of real post-combustion capture. Strain accomplishes this by reshaping the material’s geometry rather than its chemistry. Tensile deformation flattens the lattice topology and enlarges the accessible pore volume, giving CO2 molecules more room to pack inside the sheet. In effect, the stretched nanosheet becomes a roomier molecular warehouse, and the electrostatic anchors installed by scandium doping ensure that the additional guests are overwhelmingly carbon dioxide.

Yet the study’s most instructive result is what strain does not do — and what it costs. Applied to pristine C12N8, tensile strain alone delivers no improvement in CO2 uptake whatsoever; without the cationic anchors, extra pore volume is simply not enough. More importantly, in the doped system, strain boosts capacity at the expense of selectivity. The same flattening and pore expansion that lets more CO2 squeeze in also relaxes the geometric and energetic discrimination that made the unstrained material such a precise sieve. The highest selectivities belong to the unstrained doped sheet; the highest capacity belongs to the five-percent-stretched one. Engineers designing a real capture process would have to decide which figure matters more for their application, or find an intermediate strain that balances the two.

This capacity-selectivity trade-off is a recurring theme in adsorbent design, and the study frames it with unusual molecular-level clarity. Strong electrostatic interactions between open metal sites and CO2 drive both uptake and selectivity upward together, which is why scandium doping enhances both metrics. Strain, by contrast, is purely structural: it promotes CO2 packing but dilutes the selectivity advantage. The authors describe Sc-C12N8 as a promising two-dimensional molecular sieve, and the phrase is apt — the material’s performance depends on pore architecture and pore chemistry working in concert, and the simulations show precisely how each contribution can be dialed independently.

The choice of scandium is not arbitrary. The element sits among the transition metals known to form strong bonds with nitrogen, and prior work on scandium nitride films and Sc-embedded graphyne has highlighted its affinity for nitrogen-rich lattices. Embedding scandium in a carbon nitride framework therefore yields stable cationic sites rather than loosely bound decoration atoms that might cluster or leach. The study also builds on a body of earlier computational work by the same groups showing that alkali, alkaline earth, and first-row transition metal dopants can transform graphyne and covalent organic frameworks into high-performance CO2 sorbents, with the dopant’s charge and coordination environment governing how CO2 molecules arrange themselves in the pores.

Methodologically, the work illustrates the modern pipeline of adsorbent discovery. Density functional theory, with dispersion corrections to capture the weak van der Waals forces that dominate gas adsorption, provides the electronic structure and binding energetics; charge partitioning analysis quantifies the polarity that scandium introduces; and grand canonical Monte Carlo simulations using established force fields then translate those microscopic interactions into macroscopic adsorption isotherms and mixture selectivities at realistic temperatures and pressures. Because every step is computational, the results are predictions rather than measurements, but they define a concrete, testable target for synthetic chemists working on two-dimensional carbon nitrides, several of which have already been realized in the laboratory.

The broader significance lies in the design principle. Rather than searching blindly for a material that happens to capture CO2 well, the study demonstrates a modular strategy: choose a stable, porous two-dimensional framework, install cationic adsorption sites by doping, and then use lattice strain as a fine-tuning knob to trade capacity against selectivity as the application demands. As atmospheric CO2 concentrations continue to climb and carbon capture and storage moves from demonstration to deployment, materials that can be engineered at this level of precision — a single atomic layer, a single dopant species, a few percent of strain — may prove essential to making separation technology both effective and energy-efficient. The scandium-doped C12N8 nanosheet is a simulation today, but it is a simulation with a blueprint attached.

Subject of Research: Computational design of scandium-doped two-dimensional C12N8 nanosheets for CO2 capture and separation

Article Title: Balancing CO2 capture and selectivity through scandium doping and strain engineering in two-dimensional C12N8 nanosheets

Article References: Qiao, T., Zhou, S., Lu, X., & Li, Y. (2026). Balancing CO2 capture and selectivity through scandium doping and strain engineering in two-dimensional C12N8 nanosheets. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13796-4

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13796-4

Keywords: carbon capture, CO2 adsorption, two-dimensional materials, C12N8 nanosheets, scandium doping, strain engineering, density functional theory, grand canonical Monte Carlo, gas separation, molecular sieve, carbon nitride, selectivity

The significance of the subnanometre regime is difficult to overstate. In 2003, a landmark theoretical study by Junquera and Ghosez in Nature examined ultrathin ferroelectric films sandwiched between electrodes and identified a critical thickness of roughly three unit cells, below which the depolarizing field generated by incomplete charge screening would suppress the spontaneous polarization entirely. That prediction set a de facto benchmark for the community: to build ever-denser ferroelectric memories, researchers would need either better electrode screening, new material chemistries, or structural tricks that stabilize polar phases where conventional ones fail.

Gallium oxide is an unusual candidate for this challenge. In its most common form, the beta phase, Ga2O3 is a monoclinic, centrosymmetric crystal with a wide bandgap of about 4.8 electronvolts, properties that have made it a darling of power electronics but seemingly disqualifying for ferroelectricity, which requires a non-centrosymmetric structure with two energetically degenerate polar states. The material does, however, host a rich family of polymorphs, including metastable phases with different coordination geometries, and this structural flexibility is precisely what strain engineering exploits. By imposing mechanical strain, either through epitaxial growth on a mismatched substrate or through the confinement inherent in ultrathin layers, researchers can destabilize the equilibrium phase and drive the crystal into alternative structures that would not exist in bulk form.

According to the Nature Electronics analysis by Zhao Guan and Ni Zhong of East China Normal University, writing in the journal’s News and Views section, the central result they discuss involves a gallium oxide layer just half a unit cell thick. At this extreme dimension, strain engineering converts the material into a zincblende-type phase, a cubic crystal structure in which the gallium and oxygen sublattices are displaced relative to one another in a way that permits a switchable polarization. Crucially, the polarization can be reversed by an applied voltage of less than one volt, a coercive voltage low enough to be directly relevant to low-power electronic devices and compatible with the operating budgets of modern integrated circuits.

The evidence for ferroelectricity at this scale rests on what the analysis describes as both microscopic and macroscopic measurements. Microscopic probes can resolve the local atomic displacements that define the polar zincblende phase, confirming that the crystal structure itself has transformed and that the gallium and oxygen atoms occupy positions consistent with a non-centrosymmetric lattice. Macroscopic measurements, in turn, demonstrate the functional signature: a switchable polarization response that reverses under an applied electric field, the defining behavior of a ferroelectric. Together, these two lines of evidence address the most common objection to claims of ultrathin ferroelectricity, namely that apparent switching signals might arise from extraneous effects such as charge injection, electromigration or interfacial chemistry rather than genuine lattice polarization.

The low coercive voltage deserves particular attention from a device engineering standpoint. In conventional ferroelectric films, the switching voltage scales with thickness, so that aggressive miniaturization paradoxically demands enormous electric fields to reverse the polarization, fields that can exceed the breakdown strength of surrounding dielectrics and electrodes. A subnanometre film that switches below one volt inverts that logic: the same dimensional scaling that makes the film attractive for density also makes it attractive for energy efficiency. If the result can be reproduced in manufacturable device geometries, it points toward ferroelectric memory elements that operate at voltages comparable to those of mainstream CMOS logic, removing one of the long-standing barriers to integrating ferroelectrics directly into advanced chip stacks.

The work also connects to a broader wave of interest in two-dimensional and quasi-two-dimensional ferroelectrics. The analysis situates the gallium oxide result alongside recent studies of ultrathin oxide systems, including work by Zhao and colleagues published in Physical Review B in 2021 on the theoretical behavior of confined ferroelectric phases, and a 2026 Science Advances study by Shen and coauthors. Additional recent contributions from Wang, Sun and Mei in Advanced Functional Materials and from Jiang and colleagues in Nature Electronics have explored related routes to functional polarization in dimensionally confined oxides. Taken together, this literature suggests a field in transition, moving from the pessimistic critical-thickness picture of the early 2000s toward a toolkit of strain, epitaxy and dimensional confinement that can stabilize polar order in structures once thought impossible.

For gallium oxide specifically, the implications extend beyond memory. The material’s ultra-wide bandgap already underpins a growing industry in high-power transistors, solar-blind ultraviolet photodetectors and radiation-hardened electronics, and a ferroelectric polymorph accessible through strain engineering would add non-volatile functionality to a material system that is already technologically mature in other respects. Device designers have long sought ways to combine power handling with memory and sensing on a single platform; a strain-stabilized ferroelectric phase of Ga2O3 offers a conceptual route to exactly that integration, allowing polarization-based state variables to coexist with the high-voltage capability of the beta phase on related growth platforms.

Significant challenges remain before the laboratory demonstration translates into products. Strain engineering at the half-unit-cell level demands exquisite control of growth conditions, substrate choice and interface quality, and the metastable zincblende phase must remain stable through the thermal budgets of real fabrication processes. Endurance, retention and fatigue, the classic reliability metrics of ferroelectric devices, have yet to be established for this system, and the depolarizing effects that once doomed ultrathin ferroelectrics will still need careful management through electrode and interface design. The analysis by Guan and Zhong makes clear, however, that the conceptual barrier has fallen: ferroelectricity is not intrinsically incompatible with the subnanometre scale. As the authors frame it, a half-unit-cell layer of gallium oxide, reshaped by strain into a switchable polar phase and flipped by less than a volt, redefines what engineers can expect from the smallest ferroelectric structures, and it will likely energize a new round of experimental and theoretical work aimed at turning subnanometre polarization from a scientific curiosity into a working component of future electronics.

Subject of Research: Subnanometre-scale ferroelectricity induced by strain engineering in ultrathin gallium oxide layers

Article Title: Subnanometre ferroelectricity in strain-engineered gallium oxide

Article References: Guan, Z., & Zhong, N. (2026). Subnanometre ferroelectricity in strain-engineered gallium oxide. Nature Electronics. https://doi.org/10.1038/s41928-026-01702-4

Image Credits: AI Generated

DOI: 10.1038/s41928-026-01702-4

Keywords: ferroelectricity, gallium oxide, strain engineering, zincblende phase, two-dimensional materials, ultrathin films, coercive voltage, Nature Electronics, memory devices, polarization switching, wide bandgap semiconductors, critical thickness

The appeal of TMDs begins with their unusual structure. With the general formula MX2, where M is a transition metal such as molybdenum, tungsten, niobium, or tantalum and X is sulfur, selenium, or tellurium, each monolayer consists of a sheet of metal atoms sandwiched between two sheets of chalcogen atoms. Adjacent layers are held together only by weak van der Waals forces, which means bulk crystals can be peeled into single-atom-thick sheets. This architecture yields enormous surface-area-to-volume ratios, coordinatively unsaturated edge atoms with dangling bonds that serve as natural binding sites for reactive intermediates, and interlayer galleries that can host rapid ion transport. These are precisely the features that electrochemical energy devices demand.

Yet pristine TMDs carry intrinsic handicaps. The thermodynamically stable 2H phase is semiconducting, which limits charge transport; the basal plane is chemically inert and contributes little to catalysis; and narrow interlayer spacing slows ion intercalation. Exfoliated nanosheets also tend to restack during device fabrication, degrading stability and cycling performance. The review’s central message is that these limitations are not dealbreakers but design opportunities, addressable through a toolkit that includes defect engineering, heteroatom doping and alloying, strain engineering, atomic-scale modulation, nanostructure design, interlayer and phase control, and heterostructure fabrication.

Defect engineering has proven especially powerful. Sulfur vacancies in molybdenum disulfide create donor states within the band gap and expose undercoordinated metal atoms that bind hydrogen favorably. One highlighted study used high-throughput density functional theory calculations to identify the optimal vacancy configuration, then developed a hydrogen peroxide chemical etching method to distribute single sulfur vacancies uniformly across MoS2 nanosheets. The resulting catalyst achieved a hydrogen evolution overpotential of just 131 millivolts at 10 milliamperes per square centimeter, with a Tafel slope near 48 millivolts per decade and excellent stability. The authors caution, however, that defects cut both ways: they can also act as scattering centers and trap states that degrade carrier mobility, so passivation of harmful defects must accompany the deliberate introduction of useful ones.

Doping and alloying offer complementary control over electronic structure. When researchers doped MoS2 with zinc using a fusion heat method, X-ray photoelectron spectroscopy revealed binding energy shifts of roughly 0.47 and 0.40 electron volts for the Mo 3d and S 2p levels, indicating increased electron density that accelerates the hydrogen discharge step. Bimetallic strategies push further: cobalt-doped MoS2 works bifunctionally in both acidic and alkaline water splitting, while ruthenium doping wrapped in carbon nanotubes activates the otherwise inert 2H basal plane. Alloying enables continuous band gap tuning, with CVD-grown MoS2(1-x)Se2x films showing more than ten percent band gap modulation and quaternary alloys spanning 1.60 to 2.03 electron volts. Remarkably, doping can even trigger phase transitions, as rhenium concentrations above 40 percent stabilize the metallic 1T-prime phase of MoSe2.

Strain engineering adds another dimension. Because TMD monolayers can withstand more than 20 percent elastic distortion, mechanical deformation directly reshapes their band structure. Computational work predicted that only 0.3 to 3 percent uniaxial tensile strain converts 1H-MoTe2 into the quasi-metallic 1T-prime phase at room temperature, and experiments confirmed strain-induced band gap tuning in MoS2. The most striking results come from combining strain with vacancies: when sulfur vacancies in monolayer 2H-MoS2 were simultaneously strained, gap states shifted toward the Fermi level, yielding near-optimal hydrogen adsorption free energy. The combined system showed a Tafel slope of 60 millivolts per decade versus 98 for pristine MoS2, and the turnover frequency of its molybdenum atoms exceeded even that of conventional edge sites.

Phase engineering targets the most consequential lever of all. The metallic 1T phase of MoS2 conducts electricity roughly ten million times better than the semiconducting 2H phase and is hydrophilic, both critical for electrochemistry. Chemically exfoliated 1T-MoS2 reaches benchmark hydrogen evolution current densities at around 187 to 195 millivolts versus RHE, compared with more than 300 millivolts for the 2H phase, with Tafel slopes dropping from about 110 to the mid-40s. Because 1T is metastable and reverts to 2H near 92 degrees Celsius, researchers have developed stabilization tricks including sulfur intercalation, metal cation insertion, and palladium doping that partially converts the phase and slashes Tafel slopes from 157 to as low as 62 millivolts per decade.

Heterostructures and single-atom catalysts round out the toolkit. Coupling MoS2 with WTe2 creates a low Schottky barrier at the interface that shortens electron transport paths from micrometers to roughly 700 picometers, dramatically improving charge injection. Covalent 0D-2D hybrids of Co9S8 nanoparticles bonded to MoS2 through Co-S-Mo links render molybdenum sites electron-rich and activate the basal plane across all pH values. Meanwhile, isolated nickel atoms anchored on MoS2 nanofibers cut hydrogen evolution overpotentials from 263 to 161 millivolts, and nickel-oxygen sites engineered onto 1T-MoS2 achieved an onset potential near 0 volts with an overpotential of only 46 millivolts in alkaline media. In photocatalysis, single-layer 1T-MoS2 paired with nitrogen-doped graphene produced hydrogen roughly 600 times faster than comparable 2H systems under visible light.

Energy storage results are equally compelling. Vertically aligned metallic MoS2 on graphene delivered initial lithium-ion capacities near 1700 milliampere-hours per gram, while carbon-free metallic nanotube anodes retained the 1T phase for at least 120 days in air. For sodium-ion batteries, freestanding 1T-MoS2 grown on hollow graphene foam sustained stable capacities around 313 milliampere-hours per gram over 200 cycles. Supercapacitors built from restacked 1T-MoS2 films achieved volumetric capacitances of 400 to 650 farads per cubic centimeter, retaining over 93 percent of initial capacitance after 5000 cycles, and water-coupled metallic MoS2 with nanochannels reached 150 farads per gram even without conductive additives. The review concludes that scalable synthesis, long-term phase stability, and clear structure-property correlations remain the key hurdles, and it points to artificial intelligence-assisted materials discovery as the accelerant that could carry these engineered atomically thin catalysts from laboratory demonstrations to industrial deployment.

Subject of Research: Materials engineering strategies for tuning metallic two-dimensional transition metal dichalcogenides for energy conversion and storage

Article Title: Recent advances in tuning the properties of metallic 2D transition-metal dichalcogenides for energy conversion and storage

Article References: Ha, J., Park, G., Kang, G., Kang, J., Bak, H., Lee, D., Lee, H., Cho, K., & Kim, Y. (2026). Recent advances in tuning the properties of metallic 2D transition-metal dichalcogenides for energy conversion and storage. Advances in Industrial and Engineering Chemistry, 2(1), Article 5. https://doi.org/10.1007/s44405-026-00045-0

Image Credits: AI Generated

DOI: 10.1007/s44405-026-00045-0

Keywords: transition metal dichalcogenides, two-dimensional materials, hydrogen evolution reaction, phase engineering, defect engineering, heteroatom doping, strain engineering, heterostructures, lithium-ion batteries, supercapacitors, electrocatalysis, energy storage

Astaxanthin is chemically designated as 3,3′-dihydroxy-4,4′-diketo-beta,beta’-carotene, a bright red carotenoid derivative with the molecular formula C40H52O4. Its structure comprises two beta-ionone rings linked by a polyene chain containing eleven conjugated double bonds. The presence of both hydroxyl and keto functional groups at each terminus, combined with this extensive conjugated system, confers exceptional antioxidant activity, enabling the molecule to quench singlet oxygen and neutralize free radicals that would otherwise damage cells. This chemistry underpins a range of documented biological functions, including anti-aging, anti-inflammatory, immunomodulatory, antihypertensive and anticarcinogenic properties.

Not all astaxanthin is created equal. Each beta-ionone ring contains a chiral center, giving rise to three stereoisomers, and naturally derived astaxanthin consists predominantly of the all-cis (3S,3’S) form, which exhibits the strongest biological activity. Synthetic astaxanthin, by contrast, is a mixture of stereoisomers in a fixed ratio and shows roughly twenty times lower antioxidant activity; it is not approved for direct human consumption and is used mainly in aquaculture feed. Natural astaxanthin, meanwhile, has been approved as a dietary supplement and cosmetic ingredient in China, the United States and Europe, and market demand is growing at a rate of 16.2 percent, with the global market projected to reach between USD 3.4 and 3.5 billion by 2030.

Among natural producers, Haematococcus pluvialis stands apart. This widely distributed freshwater unicellular green alga, a member of the class Chlorophyceae, can accumulate astaxanthin to levels reaching four percent of its cellular dry weight, the highest content known in nature, and almost entirely in the most biologically active stereoisomer. The alga’s life cycle alternates between a green, flagellated, motile vegetative stage under favorable conditions and a red, non-motile haematocyst stage triggered by environmental stressors such as high light, elevated temperature, increased salinity or nutrient limitation. During this transition, the cells retract their flagella, thicken their cell walls and flood their cytoplasmic lipid droplets with astaxanthin esters. Yet the same biology that makes the alga remarkable also makes it commercially difficult: slow growth rates, a lengthy maturation period and demanding cultivation requirements drive up production costs and have long constrained large-scale output.

The review dissects the biosynthetic pathway in fine biochemical detail. Astaxanthin is a terpene built from the universal precursors isopentenyl diphosphate and dimethylallyl diphosphate. Unusually, H. pluvialis lacks the mevalonate pathway found in many organisms; instead, it relies exclusively on the methylerythritol phosphate pathway located in its chloroplasts, fed by pyruvate and glycerol-3-phosphate derived from glycolysis. Sequential condensation reactions catalyzed by a series of synthases build the C20 compound geranylgeranyl pyrophosphate, two molecules of which are joined by phytoene synthase, a key rate-limiting enzyme, to form the colorless carotenoid phytoene. Desaturation by phytoene desaturase and zeta-carotene desaturase, followed by cyclization by lycopene beta-cyclase, yields beta-carotene, the direct precursor of astaxanthin.

The final and most distinctive steps belong to two enzymes. Beta-carotene ketolase, encoded by BKT genes, introduces keto groups at the C-4 and C-4′ positions of the beta-ionone rings, while beta-carotene hydroxylase adds hydroxyl groups at the C-3 and C-3′ positions. BKT is highly stress-inducible and represents the most critical catalytic step specific to astaxanthin synthesis in this alga. The ketolation and hydroxylation reactions can alternate, passing through intermediates such as echinenone, canthaxanthin and adonirubin before culminating in astaxanthin, which is then esterified with fatty acids and stored stably within lipid droplets. Understanding this pathway has been greatly accelerated by systems biology: a chromosome-level genome assembly of 316 megabases across 32 chromosomes, encoding 32,416 protein-coding genes, revealed five BKT genes, and integrated transcriptomic, proteomic and metabolomic studies have mapped how stresses such as high light, sodium acetate feeding, carbon dioxide enrichment and GABA supplementation rewire metabolism to favor pigment accumulation.

To convert this knowledge into higher yields, the authors organize strain-improvement strategies into a tripartite framework of non-rational, semi-rational and rational approaches. Non-rational strategies, which do not require prior genomic knowledge, include random mutagenesis by ultraviolet light, gamma irradiation, ion beams and chemical agents such as ethyl methanesulfonate, as well as emerging plasma-based techniques. Gamma-irradiated mutants have shown astaxanthin production increases of 66 percent under salinity and high-light stress, while atmospheric and room-temperature plasma mutagenesis combined with ethanol co-treatment produced strains growing more than 45 percent faster than wild type. Adaptive laboratory evolution, which applies gradual selective pressure rather than direct mutation, has also delivered striking results: a mutant domesticated with rising carbon dioxide concentrations from 2 to 15 percent achieved biomass and astaxanthin yields 30 percent and six times those of controls, respectively. High-throughput screening methods, including the use of inhibitors such as diphenylamine and glufosinate that make overproducing colonies visually identifiable, complete this toolkit.

Rational engineering exploits the growing genomic resources to intervene precisely in the pathway. Overexpressing phytoene synthase channels carbon toward carotenoid synthesis, while a codon-optimized phytoene desaturase gene expressed in the nucleus raised herbicide resistance 43-fold and boosted astaxanthin content 26 percent over wild type under high light. Chloroplast-specific overexpression of the same gene pushed accumulation up by as much as 67 percent. Targeted overexpression of the bkt gene via Agrobacterium-mediated transformation increased astaxanthin content two- to three-fold, with intermediates rising eight- to ten-fold, and co-expression of ketolase and hydroxylase genes promises to balance catalysis and prevent intermediate buildup. Other strategies target biomass itself, including enhanced carbon dioxide assimilation through overexpression of nabI and lciA genes, which raised carotenoid accumulation 16 percent under nitrogen starvation, and the introduction of a hexose uptake protein that allows engineered strains to grow in the dark on glucose.

The review is candid about the gap between laboratory success and industrial reality. Multi-omics data often generate long lists of differentially expressed genes without clarifying which are true drivers of accumulation, and the genetic toolkit for H. pluvialis remains underdeveloped, with low transformation efficiency and limited gene-editing options; notably, no gene-editing method has yet been reported in this species, even though CRISPR-Cas9 knockout of a competing pathway gene in Chlamydomonas reinhardtii achieved a 2.3-fold astaxanthin increase. At industrial scale, the central conflict is that the high-light stress and nutrient limitation used to induce astaxanthin simultaneously suppress growth and can kill cells, making overall robustness, not single-enzyme activity, the decisive limiting factor. Heterogeneous light, nutrient and shear conditions in large photobioreactors reduce population synchrony, and the thick-walled cysts that store the pigment also raise harvesting energy costs and complicate cell disruption during extraction.

The authors see artificial intelligence as the key to closing this translational gap. Machine learning and deep learning can integrate heterogeneous multi-omics datasets to move beyond correlation and identify causal regulatory targets, while neural networks trained on cultivation data can model nonlinear relationships between light, nutrients, salinity and yield. Practical demonstrations are already emerging: machine learning applied to hyperspectral images enables non-invasive quantification of astaxanthin content in algal suspensions, deep learning systems can monitor algal cell cycles online in dynamic photobioreactors, and long short-term memory modeling of astaxanthin production in the yeast Phaffia rhodozyma achieved ten- to twenty-fold yield improvements through parameter optimization. The envisioned workflow pairs AI-built predictive models of the astaxanthin regulatory network with targeted genetic validation, feeding refined models back into strain design and real-time bioreactor control. If robust gene-editing tools, stress-tolerant chassis cells and machine-learning-guided cultivation can be integrated, the authors argue, Haematococcus pluvialis could finally be transformed from a biologically fascinating model organism into a predictable, efficient and economically viable cell factory for the world’s most powerful natural antioxidant.

Subject of Research: Biotechnological strategies for enhancing astaxanthin accumulation in the microalga Haematococcus pluvialis

Article Title: Biotechnological strategies for enhancing astaxanthin accumulation in the microalga Haematococcus pluvialis

Article References: Liu, J., Wang, Z., Chen, H., Peng, Y., & Chen, L. (2026). Biotechnological strategies for enhancing astaxanthin accumulation in the microalga Haematococcus pluvialis. Blue Biotechnology, 3(1), Article 6. https://doi.org/10.1186/s44315-026-00057-x

Image Credits: AI Generated

DOI: 10.1186/s44315-026-00057-x

Keywords: astaxanthin, Haematococcus pluvialis, microalgae, metabolic engineering, systems biology, mutagenesis, adaptive laboratory evolution, artificial intelligence, machine learning, carotenoid biosynthesis, biotechnology, strain engineering

The research team, led by Li, Fan, Fu and colleagues, targets a central weakness of conventional stretchable conductors: directional sensitivity. Instead of engineering a single “ideal” pattern, the authors generate disordered electrode structures whose mechanical response becomes statistically uniform across orientations. In practical terms, the electrode can be stretched in multiple directions without losing the continuous pathways needed for electrical conduction.

Technically, the approach relies on computational modeling coupled with data-driven optimization. The investigators treat the electrode layout as a tunable microstructure and systematically search for configurations that maintain both connectivity and conductivity as strain increases. Their design objective explicitly balances percolation-like behavior—so electrons can still travel through the network—against mechanical compliance, so the material can deform without catastrophic cracking.

The team also emphasizes geometry independence, a problem for real device fabrication. Many electrode layouts assume a particular substrate shape or boundary condition; when manufacturing differs, performance can drop. By training their design process to be robust to structural variations, the researchers produce electrode patterns that preserve conductive function even when the overall device dimensions or interface constraints change.

In tests reported alongside the design framework, the disordered electrodes demonstrate stable electrical performance under repeated stretching cycles. Rather than relying on aligned features that concentrate strain along a preferred axis, the disordered architecture disperses deformation more evenly through the network. That redistribution reduces localized failure and helps the electrode remain operational after many strain events.

The implications for viral wearable technology are significant. Direction- and geometry-independent stretchable electrodes could simplify design workflows for health monitors, motion sensors, and haptic interfaces by reducing the need for bespoke electrode layouts for each device configuration. Manufacturers could iterate faster, because the electrode pattern generation becomes a generalized process rather than a custom one.

Beyond consumer applications, the study suggests a broader design philosophy for soft electronics: letting controlled disorder—guided by data—replace fragile order. This shift may accelerate practical deployment of flexible systems in unpredictable mechanical environments, from robotic skins to adaptive medical garments.

For researchers and engineers watching the field, the work also opens a pathway to scale from simulation to fabrication. If the same modeling-and-optimization pipeline can be paired with manufacturable materials and patterning methods, robust stretchable electronics may become easier to engineer at both lab and product scale.

Subject of Research: Data-driven design of disordered structures for stretchable electrodes
Article Title: Data-driven design of disordered structures for direction- and geometry-independent stretchable electrodes
Article References: Li, M., Fan, L., Fu, Y. et al. npj Flex Electron (2026). https://doi.org/10.1038/s41528-026-00620-x
Image Credits: AI Generated
DOI: 10.1038/s41528-026-00620-x