The coatings were formed on cylindrical Ti6Al4V specimens ground to 1200 grit and chemically activated before immersion in acidic zinc-based phosphating solutions containing different concentrations of Zr4+ and Sr2+. Scanning electron microscopy revealed dendritic, acicular and lamellar phosphate crystals arranged through overlapping and staged growth. S1 produced a rough, broadly continuous layer with relatively few extensive intercrystalline areas. Its crystals had flat faces and well-defined edges, and their orientation suggested a combination of primary and secondary nucleation. S2 developed thicker and longer lamellar crystals with more visible gaps between them. S3 contained more numerous, smaller crystals and had the most compact appearance at low magnification. At higher magnification, however, its structure appeared immature, with fragmented crystals and incomplete cohesion between neighboring grains. Thus, the visual compactness of a coating did not necessarily mean that it was chemically uniform or free of local pathways for electrolyte penetration.

Energy-dispersive X-ray spectroscopy showed zinc, phosphorus and oxygen across all three coatings, together with smaller quantities of zirconium, strontium and iron. The measured zinc-to-phosphorus atomic ratios were approximately 1.34 for S1, 1.60 for S2 and 1.19 for S3. Titanium detected within the coating signals indicated that the analytical beam reached the substrate in some areas, consistent with the thin, heterogeneous layers observed by microscopy. X-ray diffraction identified hopeite, Zn3(PO4)2·4H2O, as the dominant phase in every sample. Phosphophyllite was also detected, as were strontium-zinc phosphate and hydrated zinc-zirconium phosphate phases associated with the added ions. The coatings were therefore multiphase systems rather than pure zinc phosphate layers. Their formation was interpreted as a sequence in which hopeite developed first, phosphophyllite coprecipitated, and strontium- and zirconium-containing phases formed as zinc levels fell, local pH stabilized and the layer entered a slower-growth stage.

Fourier-transform infrared spectroscopy supported the presence of phosphate groups and showed that the three coatings differed in hydration and network structure. Hydroxyl stretching bands between 3600 and 3000 inverse centimetres were strongest and broadest for S3, indicating greater hydration. S2 produced a weaker, narrower band in this region and a shift of the phosphate deformation band from about 602 to 614 inverse centimetres. The researchers associated this shift with stronger Zr-O-P interactions and a stiffer phosphate network, consistent with S2’s relatively compact and less hydrated surface. At the same time, the coating’s chemical properties could not be separated from its morphology. Zirconium concentration promoted larger phosphate crystals, whereas increasing strontium encouraged more nucleation centers and denser growth. The data support a role for both ions in coating formation, but they do not establish that either ion improves biological performance directly.

Potentiodynamic polarization tests showed that coating superiority could change with the surrounding medium. In Ringer solution, S1 had a corrosion current density of 24.7 nanamperes per square centimetre and a corrosion rate of 0.22 micrometres per year. S2 and S3 produced rates of 0.38 and 0.34 micrometres per year, respectively, still below the alloy’s 2.94 micrometres per year. S3 recorded the highest polarization resistance, 764.8 kilohm square centimetres, but that barrier measure did not translate into the lowest corrosion rate. The investigators distinguished these outcomes: S1 provided the strongest kinetic suppression of electrochemical reactions, whereas S3 offered the greatest barrier resistance and S2 the most positive corrosion potential in Ringer solution. Local penetration through intercrystalline areas could sustain corrosion even when the coating as a whole displayed a substantial overall resistance.

The same medium-dependent pattern appeared in Dulbecco’s Phosphate-Buffered Saline and Earle’s Balanced Salt Solution. In DPBS, S2 had the lowest corrosion current density, at 18.6 nanamperes per square centimetre, and the lowest corrosion rate, at 0.16 micrometres per year. S1 had the highest polarization resistance in this medium, while S3 showed more pronounced local activity and a corrosion rate of 0.74 micrometres per year. In EBSS, S3 produced the lowest rate, 0.21 micrometres per year, and the most positive corrosion potential; S2 retained the highest polarization resistance, 662.4 kilohm square centimetres. The study attributed the variation to electrolyte composition: chloride-containing Ringer solution could expose defective regions, phosphate-containing DPBS could promote passivation and pore blocking, and the chemically complex EBSS could promote hydration, ion exchange and reorganization of the coating. A formulation that ranked first under one set of conditions therefore did not necessarily rank first under another.

Electrochemical impedance spectroscopy reinforced the distinction between barrier performance and localized reactions. Fitted equivalent circuits associated the coated systems with a phosphate-layer resistance, an interfacial or pore resistance, and a charge-transfer resistance at the metal-electrolyte interface. S1 in Ringer solution had a charge-transfer resistance approximately 300 times that of uncoated Ti6Al4V, while S2’s phosphate-layer resistance reached 1.83 million ohm square centimetres. In DPBS, S2 combined a high external-layer resistance with a low current density, consistent with effective suppression of ion transfer. In EBSS, the S3 system required a Warburg diffusion element, indicating that ionic transport through hydrated or intergranular regions contributed to its response. Even with substantial impedance, low-resistance pathways remained detectable. The data therefore support a barrier mechanism while showing that coating continuity, phase stability, hydration and electrolyte-driven changes must be considered together rather than treating density or total surface coverage as sufficient measures of protection.

Wettability measurements showed that phosphating shifted Ti6Al4V from a largely hydrophobic state toward greater affinity for aqueous liquids. The water contact angle of the uncoated alloy was 89.1 degrees, whereas the initial values for S1, S2 and S3 were 43.2, 53.2 and 57.4 degrees, respectively. The coatings’ polar surface-energy components increased to roughly 19–22 millinewtons per metre, compared with 7.7 for the bare alloy. S1 had the greatest initial hydrophilicity, consistent with a lamellar surface that allowed liquid to enter intercrystalline spaces. S2 combined high roughness with a less hydrated and more strongly bonded phosphate network, while S3’s dense fine-grained structure limited capillary spreading despite its greater chemical hydration. These measurements show that contact angle depends on both surface chemistry and physical topography. They do not, by themselves, establish improved cell attachment, tissue integration or implant performance.

Exposure to the test solutions also changed the wettability of the coated surfaces. S1’s Ringer contact angle rose from 50.8 to 62.0 degrees as its polar surface-energy component fell to 16.5 millinewtons per metre. In EBSS, by contrast, its contact angle decreased from 65.2 to 56.3 degrees and its polar component rose to 27.7 millinewtons per metre, behavior consistent with hydration and chemical reorganization in the complex medium. S2’s contact angle in EBSS fell to 47 degrees while the polar component increased to 26.04 millinewtons per metre, even though its electrochemical resistance remained high. S3 retained nearly unchanged wettability in Ringer and DPBS but developed a lower polar component after EBSS exposure, consistent with reaction products that may seal local pathways. Overall, S2 provided the most consistently stable barrier response, S3 was especially effective in EBSS and maintained more predictable wetting, and S1 performed best in Ringer solution. Because the study used electrochemical and surface measurements without direct biological testing, claims about osseointegration, antibacterial activity, osteogenic response or clinical benefit remain unverified.

Subject of Research: Effects of zirconium and strontium on zinc-based phosphate conversion coatings for Ti6Al4V alloy

Article Title: Effect of Zr4+ and Sr2+ addition on morphology, surface characteristics, and corrosion behavior of a new functional Zn-based phosphate conversion coating deposited on Ti6Al4V

Article References: Burduhos Nergis, D. P., Istrate, B., Epure, E.-L., Cazac, A., Bejinariu, C., Sandu, A.-V., & Burduhos-Nergis, D.-D. (2026). Effect of Zr4+ and Sr2+ addition on morphology, surface characteristics, and corrosion behavior of a new functional Zn-based phosphate conversion coating deposited on Ti6Al4V. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13824-3

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13824-3

Keywords: Ti6Al4V, phosphate conversion coating, zirconium, strontium, corrosion resistance, electrochemical impedance, surface chemistry, wettability, biomaterials, Effect, addition, morphology

The researchers anodized titanium foil in an ethylene glycol-based organic electrolyte containing 0.4 wt.% NH4F at ambient temperature. Applied voltages ranged from 15 to 60 V, while treatment durations ranged from 0.5 to 9 h. According to the abstract, the resulting coating morphology and dimensions depended on the anodization parameters, indicating that the process was used to tune the resulting surface structure.

Mechanical testing showed lower nano-hardness for anodized surfaces than for untreated titanium foil. Specifically, the coating anodized at 45 V had a nano-hardness of 2.43 GPa, compared with 3.4 GPa for the untreated foil. The treated surface also became hydrophilic, reaching a reported contact angle of 0° after anodization at 60 V. The abstract further states that corrosion resistance and bioactivity were notably improved following anodization.

These findings support the use of anodization conditions to control properties of nanostructured TiO2 surfaces on titanium foil. However, the available evidence is limited to the study abstract: it does not provide numerical corrosion-resistance or bioactivity results, specify the bioactivity assessment method, or establish performance in animals or people. The reported results therefore characterize laboratory-treated surfaces and their potential relevance to biomedical implants and corrosion-resistant coatings rather than demonstrated clinical benefit.

Subject of Research: Experimental characterization of anodized nanostructured TiO2 coatings on titanium foil

Article Title: Physical, mechanical and electrochemical performance of nanostructured TiO2 surface on titanium developed by anodization

Article References: Gayen, T. K., Bera, T., Midya, A., & Dutta Majumdar, J. (2026). Physical, mechanical and electrochemical performance of nanostructured TiO2 surface on titanium developed by anodization. Journal of Materials Science, 61(42), 33097-33128. https://doi.org/10.1007/s10853-026-13462-9

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13462-9

Keywords: titanium foil, TiO2 coatings, anodization, surface engineering, nano-hardness, wettability, contact angle, corrosion resistance, bioactivity, experimental materials research, Physical, mechanical

Scanning probe microscopy measurements gave root-mean-square surface roughness values, expressed as Rq, of 80.91 nm for CBD, 78.18 nm for SILAR and 42.29 nm for FTCD. Thus, the FTCD coating had a markedly lower measured roughness than the two conventionally deposited films. Its Rq value was about 52% of the CBD value and slightly more than half the SILAR value. The authors described the continuous-flow reactor approach as producing a coating with lower surface roughness and better wetting behavior than the conventional coating methods, while the reported contact-angle data provide a more specific picture of the difference in water repellency.

All three coatings were hydrophobic according to their water contact angles. The measured values were 145.26° ± 3.04° for CBD, 141.09° ± 3.50° for SILAR and 130.63° ± 3.78° for FTCD. The CBD and SILAR films therefore had higher water contact angles than the FTCD film, with the FTCD value lower by about 15 degrees than CBD and 10 degrees than SILAR when the reported means are compared. Within this set of three films, the rougher CBD and SILAR surfaces were associated with greater measured water repellency, whereas the smoother FTCD surface had a lower contact angle. The results establish a relationship between surface roughness and wettability for the tested coatings, but they do not isolate roughness as the sole cause of the differences or show that the same relationship applies to other compositions or substrates.

The researchers characterized the nanocomposite films with X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy and scanning probe microscopy. These methods were used to examine structural, optical, chemical and morphological properties. Water contact angle measurements assessed the hydrophobic character of the ZnO coatings. The study’s evidence supports a comparison of the fabrication methods through the reported roughness and contact-angle values, together with the broader characterization of film structure and composition; the available summary does not specify individual values for every characterization technique or the full preparation parameters used for each method.

The findings identify a measurable trade-off between surface smoothness and water repellency in ZnO/stearic acid nanocomposite thin films. FTCD produced the lowest roughness, but CBD and SILAR produced the highest contact angles. The results may help inform the design of hydrophobic nanostructured coatings for applications including self-cleaning surfaces and corrosion inhibition, which the authors identified as potential uses for hydrophobic ZnO coatings. Because the reported comparison concerns laboratory thin films deposited on glass, the results describe fabrication-dependent differences in this material system rather than performance across different applications or operating conditions.

Subject of Research: Comparison of fabrication methods for hydrophobic ZnO/stearic acid nanocomposite thin films

Article Title: Effect of the fabrication method on the hydrophobicity of ZnO/stearic acid nanocomposite thin films: comparison of flow-through chemical deposition (FTCD) with SILAR and CBD methods

Article References: Yücel, Y., & Yücel, E. (2026). Effect of the fabrication method on the hydrophobicity of ZnO/stearic acid nanocomposite thin films: comparison of flow-through chemical deposition (FTCD) with SILAR and CBD methods. Journal of Nanoparticle Research, 28(11), Article 274. https://doi.org/10.1007/s11051-026-06794-9

Image Credits: AI Generated

DOI: 10.1007/s11051-026-06794-9

Keywords: ZnO nanocomposites, flow-through chemical deposition, chemical bath deposition, SILAR, surface roughness, water contact angle, hydrophobic coatings, wettability, thin films, Effect, fabrication, method

The choice of cyclic olefin copolymer deserves particular attention. Unlike polyimide or silicone, this class of polymer combines optical clarity, very low water absorption, excellent moisture barrier properties, and a high glass transition temperature, all of which matter for a sealed device charged with water. Gas permeability is a chronic weakness of polymeric heat pipes because non-condensable gases that diffuse through the walls accumulate in the condenser and progressively degrade performance over the device lifetime. A wall material with low permeability extends operational life and preserves the vacuum or low-saturation-pressure internal environment on which the phase-change cycle depends. The material is also inherently an electrical insulator, eliminating the risk of short circuits that metallic spreaders pose when placed directly over dense circuitry in wearables or conformal electronics.

The asymmetric architecture referenced in the work refers to an intentional imbalance between the evaporator and condenser sides of the chamber. Asymmetric vapor chambers allow the evaporation area, vapor space depth, and condensation region to be tailored independently rather than mirrored, which is valuable in flexible electronics where heat sources and heat sinks rarely align symmetrically. Combined with the patterned wettability, this geometry helps maintain a stable liquid-vapor interface even when the entire device is curved, since the capillary-driven return path remains anchored within the superhydrophilic microchannels regardless of the external bend radius.

The systematic evaluation of filling ratios reflects a well-known sensitivity in miniaturized two-phase devices. At low charge, such as the 28 percent condition tested, insufficient liquid inventory leads to dry-out of the evaporator, a runaway condition in which the wick can no longer supply fluid fast enough and the local surface temperature climbs steeply. At excessive charge, such as 70 percent, liquid pools within or beneath the vapor space, throttling vapor transport and adding parasitic thermal mass that slows startup. The intermediate filling condition, 42 percent, represents the compromise where enough working fluid saturates the microchannels while leaving the vapor lane clear. This underfilling and overfilling sensitivity mirrors observations in ultra-thin copper foam-mesh hybrid devices reported in the literature, suggesting the phenomenon is generic to thin two-phase spreaders rather than an artifact of polymeric construction.

The bending experiments provide a window into a failure mode unique to flexible thermal devices. Bending to 45 degrees can locally compress the vapor space, pinch capillary channels on the inner radius of curvature, and stretch them on the outer radius, altering both the hydraulic resistance of the liquid return path and the effective evaporation area. The finding that thermal resistance remains low and stable between 0 and 20 degrees of bending for the plasma-treated devices indicates that within this range the wettability-enhanced microchannels preserve continuous liquid feeding. The reported 20 percent reduction in thermal resistance relative to untreated microchannels quantifies the direct benefit of surface functionalization, effectively demonstrating that wettability engineering can substitute for the metallic wick structures that flexible devices cannot accommodate.

It is worth contextualizing the thermal resistance values against prior art. Flexible polymer heat pipes fabricated from laminated films with sintered mesh wicks have historically shown resistances between roughly 1 and 3 kelvin per watt under bending, while hybrid copper-silicone devices have fared somewhat better at moderate bend angles. Achieving stable low resistance across a 0 to 20 degree deformation range in a device with no metallic components at all represents meaningful progress, since hybrid designs carry penalties in weight, stiffness, and electrical conductivity that undermine the rationale for a flexible spreader in the first place. The comparison to ultra-thin copper mesh devices with effective conductivities in the thousands of watts per meter-kelvin is less about raw performance and more about the performance-per-thickness and performance-per-flexibility trade space, where two-phase devices vastly outperform any solid conductor of equal thickness, polymeric or metallic.

The oxygen plasma treatment itself is a mature technique in polymer microfabrication. Plasma exposure breaks polymer chains and introduces oxygen-containing polar groups at the surface, raising the surface energy and driving the water contact angle toward zero. Over-treatment, however, can roughen or weaken the surface and generate low-molecular-weight oxidized material, so the nine-minute optimization reflects a practical balance between wettability enhancement and preservation of channel integrity. The subsequent polyethylene glycol coating serves to stabilize the hydrophilic state. Untreated plasma surfaces on many polymers gradually recover their hydrophobicity as polar groups reorient into the bulk, a process known as hydrophobic recovery, and a hydrophilic polymer overlay retards this aging, extending the functional lifetime of the wick.

From a manufacturing standpoint, the emphasis on a complete microfabrication process in cyclic olefin copolymer matters as much as the measured performance. Polymers are compatible with replication techniques such as hot embossing, injection molding, and roll-to-roll lamination, which scale to large areas at low unit cost in a way that sintered copper wicks cannot. A fully polymeric, 250-micrometer-thick cooler that survives repeated bending could plausibly be laminated directly onto flexible printed circuit boards, integrated into textile-based wearable systems, or wrapped around robotic joints in soft actuators where rigid copper spreaders would concentrate mechanical stress. The electrical insulation of the casing further simplifies design by removing the need for intermediate dielectric layers between the spreader and exposed conductors.

The work also fits into a broader biomimetic trend in thermal engineering. Recent designs inspired by leaf venation use hierarchical, asymmetric branching networks to balance capillary pressure against permeability, since narrow channels generate strong capillarity but high flow resistance while wide channels do the opposite. Graded microchannel networks approximate this optimum. The superhydrophilic channels described here can be viewed as one ingredient in such architectures, providing the wetting limit that natural transport systems exploit, while the channel geometry governs the hydraulic side of the capillary balance.

Finally, the framing of the approach as sustainable passive cooling is substantively accurate. Two-phase spreading requires no pumps, no fans, and no electrical input, moving heat by the latent heat of vaporization of water, which is the highest of any common working fluid. Eliminating metal reduces embodied energy and material cost and removes corrosion as a lifetime-limiting mechanism. For the growing class of flexible, wearable, and soft robotic systems where every gram and every millimeter of bending compliance counts, a thin polymeric vapor chamber with engineered wettability offers a credible route to heat spreading that neither solid polymers, with their thermal conductivities below one watt per meter-kelvin, nor rigid metallic spreaders can provide.

Subject of Research: Flexible polymeric asymmetric vapor chambers incorporating microchannels of extreme wettability for electronic device cooling

Article Title: Flexible polymeric asymmetric vapor chambers incorporating microchannels of extreme wettability for electronic device cooling

Article References: Tselepi, V., Nioras, D., Gogolides, E., & Ellinas, K. (2026). Flexible polymeric asymmetric vapor chambers incorporating microchannels of extreme wettability for electronic device cooling. Frontiers in Thermal Engineering, 6, Article 1850683. https://doi.org/10.3389/fther.2026.1850683

Image Credits: AI Generated

DOI: 10.3389/fther.2026.1850683

Keywords: Flexible, polymeric, asymmetric, vapor, chambers, incorporating, microchannels, extreme, wettability, electronic, device, cooling

The central innovation lies in what the synthesis leaves out. Conventional routes to superhydrophobic surfaces typically follow two steps: first, engineers build microscopic roughness into a material, and second, they chemically treat it with fluorinated silanes, fatty acids, or other organic compounds that lower the surface energy and prevent water from sticking. Those modifiers add cost, complexity, and in some cases environmental concerns of their own, since fluorinated chemicals in particular raise questions about persistence and toxicity. Velayi’s approach instead relies on the intrinsic chemistry of copper oxide itself. By growing hierarchical urchin-like CuO structures through a facile one-step method, the study shows that the surface can reach superhydrophobicity through a subtle mechanism: hydroxylation of the copper oxide surface reduces the polar component of its surface free energy. Combined with the pronounced micro- and nanoscale roughness of the urchin morphology, that reduction is enough to push the surface past the superhydrophobic threshold.

The physics behind this behavior is the interplay between roughness and surface chemistry described by classical wetting theory. When a water droplet rests on a textured surface, it can either wet the grooves completely, as on a glass window, or sit atop the texture on a cushion of trapped air, a state known as the Cassie-Baxter regime. In the latter case, the apparent contact angle increases dramatically, and droplets roll off at slight tilts, picking up dirt particles as they go. The reported static water contact angle of 161.1 degrees, with a measurement uncertainty of about 2 degrees, places the CuO-coated mesh firmly in this regime, where only a tiny fraction of the droplet’s base actually touches the solid. Oil, by contrast, has far lower surface tension than water, so it spreads readily across the same textured surface, giving an oil contact angle of 0 degrees. A material that repels water yet welcomes oil is precisely what a selective oil-water separation filter needs.

To demonstrate the practical payoff, the researchers grew the hierarchical CuO structures in situ on a stainless-steel mesh, converting an everyday filtration material into a superhydrophobic, superoleophilic membrane. When an immiscible mixture of chloroform and water was poured onto the coated mesh, the chloroform, a dense oil, percolated through while the water was retained above the surface. The separation efficiency reached approximately 98 percent, and the chloroform permeation flux measured about 7300 liters per square meter per hour, a throughput figure that matters enormously at industrial scale, where slow filters become bottlenecks. Gravity-driven membranes with fluxes in this range can process large volumes quickly, and the fact that the coating was grown directly on the mesh rather than sprayed or glued on suggests good mechanical integration, an important consideration for filters that must survive repeated use, cleaning cycles, and abrasive slurries.

The mesh filter addresses free oil floating on water, but many real-world contamination problems are harder: oil-in-water emulsions, in which droplets of oil are dispersed so finely that they pass straight through ordinary filters. For this challenge, the study evaluated the superhydrophobic CuO powders as selective adsorbents. Because the particles attract oil and repel water, they preferentially capture oil droplets from the emulsion, and the reported oil adsorption selectivity exceeded 19, meaning the material absorbed far more oil than water by a wide margin. The paper also points toward deployment in the form of sorbent booms and pillows, the familiar containment tools used to soak up oil slicks at sea. A sorbent made from a material that strongly rejects water can hold more of its capacity for oil rather than wasting it on seawater, which is a persistent weakness of conventional polypropylene booms that gradually take up water alongside the oil they collect.

Copper oxide brings additional advantages that make the result more than a laboratory curiosity. Copper and its oxides are abundant, comparatively inexpensive, and supported by mature industrial chemistry, so scaling production of CuO powders and coatings is far less daunting than scaling exotic fluorinated treatments or rare-metal surfaces. The one-step synthesis is itself a simplification: fewer processing stages mean lower energy input, less solvent handling, and fewer opportunities for batch-to-batch variability. The absence of organic modifiers also removes a common failure mode, since organic monolayers on superhydrophobic surfaces can be stripped by abrasion, UV exposure, or solvents, silently degrading performance. A surface whose water repellence arises from its own oxide chemistry and geometry has, in principle, a more robust foundation, although long-term durability testing under mechanical wear and chemical exposure remains an essential next step for any such coating.

The environmental context sharpens the significance of these numbers. Oil spills release millions of liters of petroleum into oceans and waterways, and even routine industrial operations, from machining and metalworking to petrochemical refining, generate oily wastewater that must be treated before discharge. Separation technologies today span gravity skimmers, dissolved-air flotation, centrifuges, and polymeric membranes, each with trade-offs among cost, throughput, selectivity, and fouling resistance. Membranes that combine high flux with high efficiency are particularly attractive because they can be compact and passive, requiring no external pressure beyond gravity. A 98 percent separation efficiency with a flux near 7300 liters per square meter per hour, achieved with a coating grown on commodity stainless-steel mesh, suggests a route to filters that are both effective and cheap enough to deploy widely, including in settings with limited technical infrastructure.

There are, as with any laboratory demonstration, gaps between the bench and the open ocean. The reported experiments used chloroform as a model heavy oil, and real crude oils, diesel, and lubricants span a wide range of viscosities, densities, and surface tensions, all of which influence how quickly a superoleophilic membrane transmits them and how completely an adsorbent soaks them up. Emulsion droplet sizes in industrial wastewater can vary by orders of magnitude, and surfactants, which stabilize many emulsions, can also adsorb onto and alter the wettability of oxide surfaces. The study’s evidence for the mechanism, the synergy between hierarchical roughness and hydroxylation-driven reduction of the polar surface energy component, is consistent with the measured contact angles, but translating that understanding into predictions for other oils and other oxide systems will require further work. Recovery of absorbed oil from the powders, and regeneration of the adsorbent for reuse, are likewise practical questions that determine lifecycle economics.

Even so, the conceptual contribution is clear and potentially influential: superhydrophobicity does not always require fluorinated chemistry or elaborate organic grafting. By tuning the surface energy of an oxide through hydroxylation and pairing it with the right hierarchical texture, a common, inexpensive material can be pushed to the extremes of the wetting spectrum. That principle could extend beyond copper oxide to other transition-metal oxides, and beyond oil-water separation to anti-icing coatings, self-cleaning surfaces, and corrosion protection, all fields where the environmental profile of fluorinated modifiers has come under scrutiny. The work also underscores how much performance can be extracted from geometry alone; the urchin-like hierarchy of the CuO structures does much of the heavy lifting, amplifying a modest chemical effect into a dramatic macroscopic one.

For now, the study offers a compelling proof of concept across three complementary applications: a high-flux mesh filter for immiscible oil-water mixtures, a selective powder adsorbent for oil-in-water emulsions, and a candidate material for spill-response booms and pillows. The combination of a one-step, modifier-free synthesis, near-complete oil wetting, water contact angles above 160 degrees, 98 percent separation efficiency, and oil adsorption selectivity greater than 19 makes a strong case that copper oxide nanostructures deserve a place in the toolkit of water treatment engineers. As the peer-reviewed, open-access article by Velayi in Scientific Reports makes available to any laboratory with the relevant equipment, the barrier to reproducing and building upon the work is low, which is often the precondition for a materials discovery to travel from the journal page to the spill site.

Subject of Research: Modifier-free superhydrophobic copper oxide nanostructures for oil-water separation

Article Title: Fabrication of superhydrophobic and superoleophilic copper oxide nanostructures without organic modifiers for oil–water separation

Article References: Velayi, E. (2026). Fabrication of superhydrophobic and superoleophilic copper oxide nanostructures without organic modifiers for oil–water separation. Scientific Reports. https://doi.org/10.1038/s41598-026-75307-4

Image Credits: AI Generated

DOI: 10.1038/s41598-026-75307-4

Keywords: superhydrophobic, superoleophilic, copper oxide, oil-water separation, nanostructures, wettability, oil spill cleanup, membrane filtration, oil-in-water emulsion, surface free energy, stainless-steel mesh, adsorbent

The new material, designated BF@GO-SiO2, is the product of a carefully choreographed three-step fabrication process. The researchers began with ordinary bamboo powder, a cheap and abundant agricultural byproduct, and stripped away its lignin, the natural polymer that binds wood cells together. This delignification step leaves behind a cellulose-rich scaffold riddled with the intrinsic porosity that bamboo evolved to transport water and nutrients. Next, the team blended hybrids of graphene oxide and silicon dioxide into the fiber network. The graphene oxide sheets and silica nanoparticles serve a dual purpose: they roughen the membrane surface at the nanoscale, a critical ingredient for extreme wettability, and they reinforce the mechanical architecture of the filter. Finally, the mixture was shaped into a membrane by vacuum filtration, and chains of polyethyleneimine, a branched polymer rich in amine groups, were grafted onto the surface to fine-tune both the pore structure and the surface chemistry.

The result is a membrane with a three-dimensional, sponge-like network of interconnected channels and a surface that is simultaneously superhydrophilic, meaning water spreads across it instantly, and underwater superoleophobic, meaning oil droplets are strongly repelled when the membrane is submerged. This seemingly paradoxical combination is the secret to its performance. When an oil-in-water emulsion contacts the membrane, water wets the surface and penetrates the pores freely, forming a continuous hydration layer that acts as a molecular shield. Oil droplets, unable to adhere to or pass through the water-loving barrier, are rejected with separation efficiencies reaching 99.5 percent. The permeation flux, a measure of how much clean water passes through a given area per hour, reached an impressive 535.2 liters per square meter per hour, high enough to matter for real-world treatment plants where throughput is as important as purity.

The physics behind this behavior is worth unpacking. Wettability, the tendency of a liquid to spread on a solid surface, is governed by both surface chemistry and surface roughness. Roughness amplifies whatever tendency the underlying chemistry already has: a rough hydrophilic surface becomes even more water-attracting, while a rough hydrophobic surface becomes more water-repelling. By decorating the cellulose scaffold with graphene oxide and silica nanoparticles, the team engineered precisely the kind of hierarchical roughness that nature uses in lotus leaves and fish scales. The cellulose itself, bristling with hydroxyl groups that hydrogen-bond with water, provides the chemical foundation, while the nanoparticles provide the topographical amplification. The researchers observed that surface roughness increased in proportion to the GO-SiO2 content, giving them a tunable dial for optimizing performance.

Capillary forces add another layer of function. Because the membrane’s pores form a continuous three-dimensional network of tiny channels, water is drawn through them by capillary action, the same phenomenon that pulls liquid up a paper towel. This capillary pumping, combined with the three-dimensional water pathways carved through the porous bamboo scaffold, means the membrane does not rely solely on external pressure to drive separation. The synergy between surface hydrophilicity, capillary suction, and interconnected 3D channels explains how the material achieves both high rejection of oil and high flux of water, a combination that often involves a trade-off in conventional membranes, where smaller pores that block more oil also slow the flow.

Real industrial emulsions are rarely simple. Many are stabilized by surfactants, detergent-like molecules that coat oil droplets and give them an electrostatic or steric armor that resists coalescence. The Chinese team tested their membrane against a demanding lineup: surfactant-free emulsions as well as emulsions stabilized by the cationic surfactant CTAB, the nonionic surfactant Tween 80, and the anionic surfactant SDS. Across this entire spectrum, the membrane maintained separation efficiencies of up to 99.4 percent, demonstrating that the hydration-layer mechanism is robust against the different charge chemistries that surfactants impose on droplet surfaces. This breadth of effectiveness is a significant practical advantage, because many laboratory membranes that excel with pure oil-water mixtures falter when surfactants enter the picture.

Durability is where many promising separation materials stumble, and here the bamboo-based membrane delivered reassuring numbers. After 30 consecutive separation cycles, the membrane still achieved oil rejection above 98 percent, indicating that the hydration layer and porous architecture survive repeated wetting, fouling, and cleaning without catastrophic degradation. The membrane also performed consistently across a wide range of pH values, an important attribute given that industrial effluents can swing from acidic to alkaline. Mechanical strength, often the Achilles heel of porous bio-based filters, was equally impressive: the composite reached a maximum tensile strength of 23.5 megapascals, a figure that reflects the reinforcing contribution of the graphene oxide and silica components to the cellulose framework. A membrane that tears during handling or collapses under operating pressure is of little use regardless of its separation chemistry.

The choice of bamboo as the raw material carries environmental and economic weight. Bamboo grows rapidly, requires little in the way of pesticides or irrigation, and is cultivated on a massive scale in China and across Asia, making it one of the most renewable structural biomasses available. Previous research has already explored delignified wood and cellulose aerogels for oil-water separation, and the field has seen superhydrophobic coatings on corn straw, pine powder composites, and wood membranes decorated with functional nanoparticles. What distinguishes the present work is the integration of these strands: a bamboo-derived cellulose scaffold, graphene oxide nanosheets for roughness and strength, silica nanoparticles for surface engineering, and polyethyleneimine grafting for wettability control, all assembled through a scalable vacuum-filtration route that does not demand exotic equipment or expensive precursors.

The broader context makes the advance timely. Membrane technology is increasingly viewed as a cornerstone of sustainable water treatment, but the field faces persistent challenges: fouling, where rejected oils and contaminants clog the pores; the trade-off between selectivity and permeability; and the environmental cost of membranes made from petroleum-derived polymers and fluorinated chemicals. Bio-inspired superwetting membranes, which borrow the surface strategies of plants and animals, offer a route around several of these obstacles, and cellulose-based systems in particular promise biodegradability and low cost. The Sichuan team’s membrane, with its antifouling hydration layer, high flux, and plant-based backbone, fits squarely into this trajectory and, according to the authors, offers a scalable strategy for fabricating high-performance separation membranes with significant potential for practical oily wastewater treatment.

There is, of course, a distance between laboratory beakers and municipal treatment lagoons, and questions of long-term cost, large-area fabrication, and performance with real, chemically complex effluents will determine whether bamboo membranes make the leap. But the numbers reported by Xu and her colleagues, 99.5 percent separation efficiency, a flux above 535 liters per square meter per hour, stability over 30 cycles and across wide pH conditions, and tensile strength of 23.5 megapascals, represent a compelling proof of concept. In a world where oily discharge from industry, shipping, and urban runoff continues to threaten ecosystems and human health, the idea that a fast-growing grass, a sheet of graphene oxide, and a sprinkle of sand-like silica could together turn toxic emulsions into clean water is exactly the kind of elegant, sustainable chemistry that water treatment has been waiting for. The research was supported by the Sichuan Science and Technology Program and a university discipline construction fund, and the team included researchers from the College of Forestry and affiliated key laboratories at Sichuan Agricultural University.

Subject of Research: A bamboo fiber and graphene oxide-silica composite membrane for oil/water emulsion separation

Article Title: Hierarchically porous bamboo fiber@ GO-SiO2 composite membrane for efficient oil/water emulsion separation

Article References: Xu, H., Guan, C., He, Y., Mei, T., Su, Z., & Ning, L. (2026). Hierarchically porous bamboo fiber@ GO-SiO2 composite membrane for efficient oil/water emulsion separation. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13837-y

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13837-y

Keywords: bamboo fiber, graphene oxide, silica nanoparticles, oil-water separation, superhydrophilic membrane, emulsion separation, wastewater treatment, cellulose, wettability, membrane technology, polyethyleneimine, sustainable materials

The films were made with one of the simplest and cheapest techniques in materials science: sol–gel spin coating. The researchers dissolved zinc acetate dihydrate in 2-methoxyethanol with monoethanolamine as a stabilizer, added nickel acetate or lithium acetate at a 5 percent doping level, stirred the solutions at 60 degrees Celsius, and spun them onto glass at 3000 rpm. Ten coating cycles, each followed by a brief bake at 200 degrees, built up films thick enough to study, and a final anneal at 400 degrees for an hour locked in good crystallinity. For the electrochemical measurements, the same recipe was applied to fluorine-doped tin oxide electrodes. The low-temperature, solution-based route matters because it avoids the expensive vacuum equipment of sputtering or spray pyrolysis, keeping the door open for large-area, low-cost manufacturing.

X-ray diffraction confirmed that every film, doped or not, crystallized in the hexagonal wurtzite structure of zinc oxide, with no impurity phases sneaking in. The main diffraction peaks, corresponding to the (100), (002) and (101) crystal planes, shifted slightly to higher angles in the doped samples — a fingerprint that the foreign atoms had actually taken up zinc sites in the lattice rather than clustering into separate compounds. Using Scherrer’s equation on the dominant (002) peak, the team calculated average crystallite diameters of 23.79 nanometers for pure ZnO, 20.82 nanometers for the Ni-doped film and 22.5 nanometers for the Li-doped film. Rietveld refinement of the diffraction data gave a weighted profile factor of 9.35 percent and a goodness-of-fit of 2.56 for the parent compound, indicating a solid structural model.

Under the scanning electron microscope, all three films revealed a wrinkled surface texture studded with nanograins. The wrinkles, the authors suggest, arise from compressive stress that builds up as the wet film dries and the temperature difference between substrate and material drives shrinkage; the dopant atoms add their own tensile stress as they squeeze into zinc sites. Energy-dispersive X-ray spectroscopy verified the presence of zinc, oxygen and, in the nickel case, the dopant itself. Lithium, with an atomic number of just 3, sits below the detection threshold of EDS, which can only resolve elements heavier than atomic number 5, so its incorporation had to be inferred from the X-ray peak shifts instead.

Optically, the undoped film was the star of transparency, transmitting more than 90 percent of visible light. Doping dimmed that performance — below 80 percent for nickel and below 85 percent for lithium — because impurity atoms scatter light and disrupt crystallinity. Yet doping also delivered something valuable: a slight red shift of the absorption edge and a narrowing of the optical band gap, from 3.33 electronvolts in pure ZnO to 3.30 for Ni-ZnO and 3.315 for Li-ZnO, as extracted from Tauc plots. The team attributes the narrowing to higher carrier concentrations introduced by the dopants, with crystallite size, strain and lattice parameters also playing a role. Band gap engineering of this kind is precisely what supercapacitor designers look for, since a smaller gap can improve charge transfer at the electrode surface.

Deeper optical analysis sharpened the contrast between the two dopants. The lithium-doped film kept its refractive index below 2 across the visible spectrum, while the nickel-doped film pushed above 2, and the extinction coefficient — a measure of optical loss — was correspondingly lower for lithium. Packing density, computed from the refractive index, was highest for the Ni-doped film, and the volume and surface energy loss functions showed that energy dissipation occurred mainly inside the films rather than at their surfaces. Optical conductivity rose steadily with photon energy in all samples as photons excited electrons across the gap. Taken together, the optical data mark the lithium-doped film as the better candidate for transparent optoelectronic devices.

The wettability experiments produced perhaps the most striking result. A plain water droplet beads up on the Ni-doped film at a contact angle of 105 degrees — comfortably hydrophobic — while the Li-doped film sits at 85 degrees and pure ZnO at 68 degrees, both hydrophilic. The rougher nickel surface traps air under the droplet, propping it up. But when the films were bathed in 254-nanometer ultraviolet light, whose photons carry more energy than the band gap, all three surfaces flipped toward superhydrophilicity within 5 to 15 minutes as photoexcited electrons trapped water molecules and spread the droplet. The Ni-doped film transformed fastest, its contact angle falling to just 0.07 of its initial value after 15 minutes. Left in the dark, the surfaces recovered their original wettability over 21 to 24 hours, a reversible switch with obvious appeal for self-cleaning coatings on windows and photovoltaic panels.

Electrically, lithium pulled decisively ahead. Four-point probe measurements gave sheet resistances of 32.24, 29.37 and 27.1 megaohms per square for the undoped, Ni-doped and Li-doped films respectively, translating into conductivities of 0.134, 0.147 and 0.159 siemens per meter. Doping populates the material with interstitial atoms and oxygen vacancies that ionize easily and release charge carriers, and the lithium film’s better crystalline quality appears to have let those carriers move more freely. For anyone designing transparent electrodes or electronic devices on top of these films, that difference in conductivity is not a rounding error — it is a meaningful edge.

The electrochemical tests, run in a three-electrode cell with 1 molar potassium hydroxide, showed that doping converts ZnO from a resistor-like electrode into a genuine capacitor. Cyclic voltammetry at scan rates from 10 to 100 millivolts per second produced nearly ideal rectangular curves centered on the zero-current axis for both doped films — the classic signature of an electric double-layer capacitor, where charge is stored by fast, reversible ion adsorption rather than by chemical redox reactions. The curves stayed symmetrical even at the highest scan rates, and their enclosed area grew with scan rate as more ions became available to build the double layer. The Li-doped film enclosed the largest area, and galvanostatic charge–discharge measurements quantified the advantage: specific capacitances of 50.16 farads per gram for Li-ZnO versus 33.54 farads per gram for Ni-ZnO at a current density of 0.2 milliamperes per gram, dropping to 35.84 and 24.2 farads per gram at 0.4 milliamperes per gram. Both figures beat a recently reported value of 31.94 farads per gram for an undoped ZnO film, and the team links the capacitance gain to the same band gap narrowing seen optically, with dopant-induced defects extending charge and discharge times through improved ionic mobility.

The broader lesson is that neither dopant is simply better; each earns its place depending on the job. Lithium-doped ZnO is the pick for thin-film supercapacitors and conductive transparent layers, thanks to its superior conductivity, optical clarity and charge storage. Nickel-doped ZnO, with its hydrophobic-to-superhydrophilic switch and stronger band gap reduction, suits self-cleaning surfaces and applications where tailored absorption matters. And because lithium is relatively scarce in nature, the authors note that nickel could serve as a viable substitute where its particular strengths suffice. For a material as cheap and versatile as zinc oxide, a drop of the right impurity — just 5 percent by weight, added in a beaker at 60 degrees — turns out to be enough to reshape its electronic, optical and surface chemistry in ways that matter for the next generation of energy storage devices.

Subject of Research: Comparative effects of nickel and lithium doping on the structural, optical, electrical and electrochemical properties of sol–gel zinc oxide thin films for energy storage

Article Title: Comparative analysis of Ni and Li doped ZnO with enhanced structural, optical, and electrochemical performance in energy storage applications

Article References: Baig, F., Zaheer, Z., Khan, R., Althubeiti, K., Al Otaibi, S., Abdullaev, S., Elboughdiri, N., & Khan, A. (2026). Comparative analysis of Ni and Li doped ZnO with enhanced structural, optical, and electrochemical performance in energy storage applications. Journal of Saudi Chemical Society, 30(2), Article 20. https://doi.org/10.1007/s44442-026-00056-y

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00056-y

Keywords: zinc oxide, thin films, doping, nickel, lithium, supercapacitors, sol-gel spin coating, band gap, wettability, electric double-layer capacitor, optical properties, energy storage

The study, published in the journal Environmental Geochemistry and Health by a team led by Hongyang Wang of Liaoning University together with colleagues from Northeastern University and Inner Mongolia Yitai Guanglian Coal Chemical, addresses a stubborn technical bottleneck. Coal seam water injection, in which water is pumped into a seam ahead of mining to pre-wet the coal, has long been a frontline dust control strategy. But conventional water struggles to infiltrate the pore and fracture networks of deep coal, especially when mixed metallic substances within the coal matrix block penetration. The result is uneven wetting, dry zones that shatter into inhalable dust during extraction, and suppression rates that fall far short of what occupational health standards demand.

The researchers’ solution is a composite formulation built from three widely available components: sodium gluconate, abbreviated SG, fatty alcohol polyoxyethylene ether known as AEO-3, and sodium fatty alcohol polyoxyethylene ether sulfate, or AES. Each ingredient plays a distinct role. Sodium gluconate, a chelating agent, is capable of binding the metallic substances dispersed in the coal, thereby clearing obstacles that would otherwise impede water movement through the coal’s internal pore structure. AEO-3, a nonionic surfactant, and AES, an anionic surfactant, work in combination to lower the surface tension of the injection solution and reduce the contact angle at the water-coal interface, two of the most important physical parameters governing how readily a liquid spreads across and soaks into a hydrophobic solid surface.

Coal is notoriously water-repellent. Its surface is dominated by hydrophobic carbon structures with relatively few oxygen-containing functional groups, the chemical handles to which water molecules can attach. The SAA formulation changes this chemistry. According to the team’s laboratory characterization, treatment with the agent increased the number of oxygen-containing functional groups on the coal surface, giving water more anchoring points and improving wettability at the molecular scale. At the same time, the surfactants promoted agglomeration of micron-sized coal dust particles, causing individual fine grains to clump into larger, heavier particles that settle out of the air more readily. The effect on particle size distribution was quantifiable: the median particle size, known as the D50 value, increased by 22.58 percent compared with untreated dust.

To test how these microscopic changes translate into real dust control performance, the team constructed a custom dust-suppression simulation system in the laboratory. The apparatus allowed them to generate airborne coal dust under controlled conditions and measure how effectively different spray solutions captured it. When SAA-treated water was used, the effective dust-suppression rate reached 71.50 percent. That figure is 2.17 times the performance of traditional water-mist dust suppression, meaning the formulated agent more than doubled the capture efficiency achievable with plain water alone. For an industrial process where even marginal gains in suppression translate into measurably lower respirable dust exposures for miners, a performance margin of this size is significant.

The most consequential part of the study, however, took place underground. The researchers carried out on-site dust suppression tests at the 3-802 working face of a production coal mine, injecting SAA-treated water into the seam using standard water injection equipment. Before injection, dust sampling established baseline conditions. After treatment, the average coal dust particle size at the face had risen to 2.53 times its pre-injection value, confirming that the agglomeration effect observed in the laboratory survived the journey from bench to bordeline. Larger particles mean less respirable dust, faster settling and cleaner air at the point where miners actually work.

Monitoring across multiple underground measurement points showed total dust suppression rates ranging from 60 to 84 percent, a broad but consistently strong performance envelope that reflects the natural variability of ventilation, mining activity and seam conditions across a working face. Beyond improving air quality, the treatment appeared to influence the mechanical behavior of the coal itself. The team reports that SAA water injection reduced the tendency of the coal to fracture and generate dust, a property linked in earlier research to burst liability, the dangerous propensity of some deep coal seams to fail suddenly and violently. By softening this tendency, the agent may offer a secondary safety benefit against rock bursts and coal bursts, phenomena that remain among the most feared hazards in deep mining.

What distinguishes this work from many prior surfactant studies, the authors argue, is the full chain of evidence it assembles. Laboratory mechanism analysis, surface chemistry characterization, particle size measurement, simulation chamber testing and underground field trials are all presented in a single integrated study, closing the gap that so often separates promising bench chemistry from deployable engineering practice. The funding came from the National Natural Science Foundation of China under grant 52427805, and the work involved authors from Liaoning University’s School of Environmental Sciences, Northeastern University’s School of Resources and Civil Engineering, and Inner Mongolia Yitai Guanglian Coal Chemical, a collaboration that pairs academic environmental science with direct industrial access.

The implications extend beyond a single mine. Deep coal mining is expanding in major producing nations, and occupational dust exposure remains a leading cause of preventable disease among miners, including coal workers’ pneumoconiosis, an incurable and often fatal lung condition. The health burden of coal dust has been documented extensively in the occupational health literature, and regulators continue to tighten permissible exposure limits. Technologies that make existing controls, such as water injection and water sprays, substantially more effective without requiring wholesale redesign of mining equipment are therefore valuable. The SAA formulation uses relatively inexpensive, commercially available chemicals, which the authors suggest positions it for practical engineering application.

Challenges remain before widespread adoption. Field performance will need to be validated across seams of different rank, metamorphic grade and mineralogy, since the wetting behavior of coal varies considerably with its chemical composition. Long-term dosing, environmental discharge and cost at scale will also require scrutiny. Nevertheless, the reported numbers give the approach credibility: a doubling of mist suppression efficiency in the lab, suppression rates of up to 84 percent underground, and a measurable reduction in fracturing tendency all point toward a wetting agent that does more than tweak surface tension. By combining chelation, nonionic and anionic surfactant synergy, and verified field performance, the SAA study offers deep coal mines a concrete new tool in the long-running fight against dust, and offers miners something even more precious: cleaner air at the coal face.

Subject of Research: A composite SAA wetting agent for enhancing coal seam water injection and dust suppression in deep coal mining

Article Title: High-efficiency ‘SAA’ wetting agent for coal mine dust control: from preparation and mechanism to field application

Article References: Wang, H., Zhao, T., Wang, H., Wang, H., Leng, Y., Pan, Y., Xu, L., & Zhu, Y. (2026). High-efficiency ‘SAA’ wetting agent for coal mine dust control: from preparation and mechanism to field application. Environmental Geochemistry and Health, 48(15), Article 600. https://doi.org/10.1007/s10653-026-03491-3

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03491-3

Keywords: coal mining, dust suppression, wetting agent, coal seam water injection, surfactants, deep mining, occupational health, coal dust, sodium gluconate, wettability, Environmental Geochemistry and Health, rock burst

The research team, led by Guangpei Lin of Wuhan University of Science and Technology together with colleagues at the Guangdong Academy of Sciences, Jinan University and City University of Hong Kong, used laser direct energy deposition, or LDED, to fabricate composite coatings in which varying amounts of diamond powder were blended into FeCoCrNi high-entropy alloy feedstock. LDED is an additive manufacturing technique in which a focused laser beam melts powder as it is fed through a nozzle, building up dense metallic layers layer by layer. Because FeCoCrNi is a canonical high-entropy alloy, containing near-equal atomic fractions of iron, cobalt, chromium and nickel, it offers an unusually robust and ductile matrix in which to embed brittle reinforcement particles.

Embedding diamond in metal is notoriously difficult. Diamond is the hardest known bulk material, giving it enormous potential as a wear-resistant reinforcement, but it is also thermodynamically unstable at the temperatures reached in a laser melt pool. At high temperature and in contact with certain molten metals, diamond can graphitize, converting from its prized cubic crystal structure into soft graphite, which destroys its load-bearing capacity. Worse, many metals do not wet diamond well, meaning the molten alloy fails to bond to the particle surface and leaves gaps that act as ready-made crack starters under mechanical load.

The new study reveals that the FeCoCrNi system overcomes both obstacles through a fortunate combination of physics and chemistry. During deposition, the diamond particles, being far less dense than the surrounding molten alloy, experience buoyancy forces. At the same time, steep temperature gradients across the melt pool drive Marangoni convection, a circulating flow generated by surface tension differences that stirs the liquid metal. Acting together, these forces preferentially transport the diamond particles upward, enriching them at the coating surface. This is a significant advantage: the very region of the coating that experiences the most severe sliding contact and abrasion in service is precisely the region that ends up with the highest concentration of the superhard phase.

Wettability, the ability of the melt to spread over and adhere to the diamond surface, proved equally important. The researchers found that the compositional compatibility between cobalt-rich coating material and the FeCoCrNi substrate improved wetting of the diamond by the melt, allowing the liquid alloy to embrace the particles closely rather than leaving deleterious voids around them. Good wetting is a prerequisite for strong interfaces in any metal-matrix composite, because load applied to the coating must transfer efficiently from the ductile alloy into the stiff, hard particles for those particles to shield the surface from wear.

The decisive chemical trick, however, involves chromium. As the melt pool solidifies, chromium atoms from the alloy react in situ with carbon atoms at the diamond surface, forming a thin chromium carbide layer at the particle-matrix interface. This carbide layer performs two critical functions simultaneously. First, it acts as a diffusion barrier and chemical buffer that suppresses the graphitization damage that would otherwise degrade the diamond during the thermal cycle. Second, it creates a strong, adherent bridge between particle and matrix, enhancing the interfacial bond strength so that the diamond can fully exploit its load-bearing reinforcement role. The diamonds also promote the formation of additional carbides in their vicinity, further raising the hardness of the surrounding matrix.

The team systematically varied the diamond content and found a clear optimum. At 20 percent diamond, the coating exhibited the best combination of microstructure, interfacial bonding and tribological performance. In wear testing, this optimal coating reduced wear loss by 16.2 percent and wear volume by 40.5 percent relative to a pure FeCoCrNi coating produced under the same conditions. Detailed examination of worn surfaces showed that the diamond-rich surface layer shields the underlying material, shifting the dominant wear mechanism to relatively benign abrasive wear. Under impact loads and compressive stresses, some diamond particles do flake out of the surface, leaving small pits, but the overall damage remains far milder than in the unreinforced alloy.

Just as instructive is what happens when the diamond content departs from the optimum. Excessive diamond loading disrupts the continuity of the metallic matrix and weakens interfacial bonding, so particles detach early during sliding. Once freed, these detached particles roll between the coating and the counterface as third-body abrasives, gouging the surface and accelerating material removal, a self-defeating outcome that the moderate, 20 percent formulation avoids. Moderate loading keeps the matrix continuous, maintains stable bonding and prevents the early particle detachment that would seed third-body abrasion. The result is a coating in which each diamond particle remains anchored, load-bearing and protective throughout its service life.

The implications extend across industries in which surface wear dictates component lifetimes: mining tools, drilling and cutting equipment, forming dies, pumps and aerospace actuators all depend on hard coatings, and laser direct energy deposition is already attractive for repairing and resurfacing expensive parts in place. By showing that a high-content diamond reinforcement can survive additive manufacturing and deliver measurable tribological gains in a ductile high-entropy alloy, the study offers a practical recipe for next-generation protective coatings. The work also contributes fundamental insight into how buoyancy and Marangoni convection can be harnessed, rather than merely tolerated, to position reinforcement particles where they are most useful, and how a single reactive alloying element, chromium, can be recruited to protect a fragile superhard phase from thermal destruction during processing.

The research was supported by the National Natural Science Foundation of China, the Guangdong Provincial Key R&D Program, the Advanced Materials National Science and Technology Major Project, the Guangdong Basic and Applied Basic Research Foundation, the Guangdong-Hong Kong Joint Laboratory of Modern Surface Engineering Technology and several provincial and municipal programs. Correspondence for the study is handled by Zhaobing Cai of Wuhan University of Science and Technology and Bingwen Lu of the Guangdong Academy of Sciences. As additive manufacturing continues to mature from prototyping into production of demanding engineering components, strategies that unite process physics with interface chemistry, as demonstrated here, are likely to define the next wave of wear-resistant surface engineering.

Subject of Research: Diamond-reinforced FeCoCrNi high-entropy alloy coatings fabricated by laser direct energy deposition

Article Title: High-content superhard diamond enhances hardness and wear resistance in LDED FeCoCrNi high-entropy alloy

Article References: Lin, G., Cai, Z., Gu, L., Dong, Z., Feng, L., Huang, X., Dai, S., Zhang, P., Yan, X., & Lu, B. (2026). High-content superhard diamond enhances hardness and wear resistance in LDED FeCoCrNi high-entropy alloy. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13720-w

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13720-w

Keywords: high-entropy alloy, diamond composite, laser direct energy deposition, wear resistance, hardness, chromium carbide, Marangoni convection, wettability, abrasive wear, FeCoCrNi, coatings, tribology

The material at the heart of the study is the insoluble rice bran natural complex, or IRBNC, a composite left behind when soluble proteins and bioactive polysaccharides are extracted from defatted rice bran. Roughly half of the defatted bran ends up in this residue, in which tightly bound proteins, insoluble polysaccharides, and phenolic compounds form networks so robust that conventional separation techniques struggle to dismantle them. Rather than fighting this recalcitrance, the researchers embraced it. Because plant-derived natural complexes are assembled in situ during plant growth through cross-linking of proteins, polysaccharides, and polyphenols, they possess a structural integrity and richness of intermolecular interactions that artificially blended systems cannot match. The problem was that their particle sizes were uneven and their surface chemistry unoptimized for interfacial work.

Earlier work by the same group had shown that mechanical pretreatment could partially improve the wettability of IRBNC particles, and that the green tea catechin EGCG could markedly enhance their emulsion-stabilizing capacity. But a critical question remained open: were EGCG’s benefits unique to its particular structure, or did they depend on generalizable features such as the number of phenolic hydroxyl groups and the presence of a galloyl moiety? To answer this, the team selected three representative catechin monomers—epicatechin (EC), epigallocatechin (EGC), and epicatechin gallate (ECG)—which differ systematically in hydroxyl count and galloylation, and conjugated each of them to IRBNC at three dosages: 25, 50, and 100 milligrams of catechin per gram of complex.

The evidence for genuine interaction was unambiguous. Bound phenol content rose with catechin dosage, although binding efficiency fell at higher loadings, indicating that the complex surfaces saturate at around 25 milligrams per gram. Free amino and sulfhydryl groups in the proteins declined steadily, consistent with quinone-mediated covalent reactions under the alkaline conditions used for conjugation, alongside extensive hydrogen bonding. Infrared spectroscopy showed attenuated hydroxyl and carbonyl bands, while X-ray diffraction revealed that the semi-crystalline cellulose signature of the complex broadened and weakened, signaling a shift toward a more amorphous, flexible architecture. Protein secondary structure analysis confirmed partial unfolding, with ordered alpha-helices and beta-sheets giving way to more disordered conformations that favor interfacial adsorption.

Wettability emerged as the decisive parameter. Native IRBNC particles, with a water contact angle of roughly 127 degrees, are so hydrophobic that they resist stable positioning at oil–water interfaces. Catechin modification progressively introduced hydrophilic hydroxyl groups, pushing the contact angle toward the golden value of 90 degrees at which particles anchor most effectively. ECG-modified particles reached 91.05 degrees at just 25 milligrams per gram, while EGC required 50 milligrams per gram to approach the same range. Interfacial tension measurements confirmed the functional payoff: equilibrium tension at the oil–water boundary dropped from 20.43 to 16.19 millinewtons per meter after modification, reflecting faster and denser particle adsorption and stronger interfacial film formation.

When the modified particles were used to prepare oil-in-water Pickering emulsions, the benefits carried through. Droplet sizes shrank to around 46 to 49 micrometers at optimal dosages, compared with large, heterogeneous droplets stabilized by unmodified IRBNC. Confocal microscopy visualized continuous fluorescent shells of protein and polysaccharide encasing the oil droplets, evidence of compact interfacial layers built from the reorganized complexes. Rheological testing showed enhanced viscoelasticity, with storage moduli exceeding loss moduli across the tested frequency range, indicating emulsions with a robust, elastic network character rather than a fragile suspension of isolated droplets.

Oxidative stability improved in parallel. During 30 days of accelerated storage at 45 degrees Celsius, emulsions stabilized by moderately modified particles accumulated fewer lipid hydroperoxides and lower levels of thiobarbituric acid reactive substances, the markers of primary and secondary oxidation respectively. The researchers attribute this dual protection to the synergistic action of catechin antioxidant chemistry—phenolic hydroxyls scavenging free radicals—and the physical barrier formed by particle-laden interfaces, which restricts oxygen diffusion and shields lipid substrates from pro-oxidants. ECG, with its galloyl group and highest hydroxyl density, delivered the strongest suppression of both oxidation markers.

The study also carries a clear warning about dosage. At excessive catechin concentrations of 50 to 100 milligrams per gram, particles over-crosslinked and aggregated, wettability overshot into excessive hydrophilicity, and emulsion stability deteriorated—droplets coarsened, creaming intensified, and oxidation markers climbed. This structure–dosage–function triangle means that each catechin demands its own optimal loading: 25 milligrams per gram for EC and ECG, and 50 for EGC. The galloyl-bearing ECG proved the most efficient overall performer, achieving tight interfacial packing and superior stability at low dosage, whereas the smaller EC adsorbed rapidly but formed weaker films.

Beyond the immediate numbers, the work establishes a rational design principle for natural Pickering stabilizers: molecular features of polyphenols—hydroxyl density and galloyl substitution—can be used as tunable levers to restructure insoluble plant complexes for interfacial duty. Given the enormous global stream of rice bran waste, the approach offers a route to convert a low-value by-product into functional ingredients for beverages, sauces, encapsulated nutrients, and delivery systems for lipophilic bioactives. The authors note that advanced molecular and interfacial characterization will be needed to fully resolve the interaction pathways and assembly mechanisms at oil–water interfaces, but the demonstration that a tea molecule’s architecture can dictate the fate of a rice milling residue is a striking example of structure-guided food materials engineering.

Subject of Research: Structure-dependent interfacial modification of insoluble rice bran natural complexes by catechin monomers for Pickering emulsion stabilization

Article Title: Enhancing Pickering emulsion stabilization of insoluble rice bran natural complexes: Structure-dependent interfacial regulation by catechin monomers

Article References: Cui, H., Li, H., Yu, E., Wu, X., Lin, L., & Wu, W. (2026). Enhancing Pickering emulsion stabilization of insoluble rice bran natural complexes: Structure-dependent interfacial regulation by catechin monomers. Current Research in Food Science, 13, Article 101554. https://doi.org/10.1016/j.crfs.2026.101554

Image Credits: AI Generated

DOI: 10.1016/j.crfs.2026.101554

Keywords: Pickering emulsion, rice bran, catechins, EGCG, ECG, interfacial regulation, wettability, lipid oxidation, protein-polysaccharide complex, food-grade stabilizer, tea polyphenols, emulsion stability