Hydrogen embrittlement remains a critical bottleneck limiting the reliability of structural materials in hydrogen energy systems, thus fueling the imperative demand for high-performance hydrogen permeation barriers (HPBs). Ceramic nano-multilayer coatings offer unique advantages over single-layer counterparts by leveraging interface-driven hydrogen trapping and blocking. Herein, Al2O3/TiO2 nano-multilayer coatings with tailorable period thicknesses (2–50 nm) were fabricated on T91 steel via atomic layer deposition. Their microstructure, electrochemical behavior, and hydrogen permeation resistance were systematically characterized. The results demonstrate that the as-prepared coatings exhibit a dense, amorphous microstructure, accompanied by superior corrosion resistance compared to single-layer Al2O3, TiO2, and the bare T91 substrate. Notably, a non-linear correlation between hydrogen permeation resistance and period thickness was unveiled, a discovery that fills a critical knowledge gap in the field of HPBs design. Specifically, hydrogen permeation resistance was found to rise with increasing interface number up to a critical value, beyond which insufficient spatial isolation of hydrogen-induced defects gives rise to interconnected diffusion pathways and degraded barrier efficiency. The optimal Al2O3/TiO2 nano-multilayer coating achieves an order-of-magnitude reduction in the hydrogen diffusion coefficient relative to the T91 substrate, arising from the synergistic effect of interface-mediated hydrogen trapping and effective segregation of hydrogen-induced defects. This work elucidates the fundamental structure-performance relationship governing Al2O3/TiO2 nano-multilayer coatings and provides key insights into interface engineering and period thickness optimization for next-generation HPBs in hydrogen energy applications.
Tailoring interface structure is an effective strategy to enhance the mechanical performance of bimetallic laminated composites (BLCs). A nanometer-scale interfacial solid solution layer (ISSL) was engineered in Cu-Ni-Si/1010 steel BLCs via continuous solid/liquid bonding followed by multi-pass cold rolling. The Fe-based ISSL enriched with Cu, Ni, and Si forms between the two layers, which becomes thinner and develops an undulating morphology after rolling. The interfacial orientation deviation from the ideal Kurdjumov-Sachs ({111}Cu//{110}Fe) relationship increases from 7.2° to 15.7° after 90 % rolling reduction due to the formation of the new interfaces. The heterogeneous interface with higher deviation exhibits a larger strengthening effect, achieving an improvement in yield strength of 114 MPa and ultimate tensile strength of 90 MPa compared with the calculations by the rule of mix. The ISSL promotes dislocation accumulation during rolling, which impedes the intragranular dislocation slip, resulting in dislocation tangles and pile-ups. Three-dimensional discrete dislocation dynamics simulations further demonstrate that the deformation-induced high-angle deviation significantly improves the energy barrier for dislocation slip transmission across the interface, improving the yield strength of BLCs. This work provides a strategy for high-performance design of advanced BLCs and reveals the multiscale strengthening mechanisms of the ISSL.
Solar interfacial evaporation is considered a promising approach for freshwater production. However, in high-salinity environments, severe interfacial heat loss and continuous salt accumulation and crystallization hinder the long-term stable operation of evaporators. To address this issue, a thermally adaptive Janus composite aerogel (JNCC) was constructed by integrating a CuS/MMT-based photothermal top layer containing an in situ poly(N-isopropylacrylamide) (PNIPAM) interpenetrating network with a hydrophilic ion-buffering bottom layer. Through the lower critical solution temperature (LCST) behavior of PNIPAM, the aerogel exhibits temperature-driven reversible wettability switching, thereby dynamically regulating interfacial water transport and salt-ion migration. Under illumination, the material surface transitions to a hydrophobic state, reducing interfacial heat loss and inhibiting salt accumulation; when illumination weakens or ceases, the surface regains hydrophilicity, promoting water reflux and dissolving deposited salt crystals, thereby achieving self-cleaning in the dark. The optimized JNCC achieves an evaporation rate of 3.29 kg m−2 h−1 under 1 sun conditions and maintains a stable evaporation rate of 3.10 kg m−2 h−1 in a 20 wt% NaCl solution, with a salt dissolution rate of 0.8 kg m−2 h−1 in the dark. Mechanistic analyses indicate that the thermoresponsive interpenetrating network promotes the accumulation of intermediate water, reduces the effective enthalpy of evaporation, and works in concert with the asymmetric ion-buffering structure to suppress upward salt migration, thereby decoupling water supply from salt accumulation. This aerogel maintains excellent performance even after four months of natural evaporation in water. This study proposes a design strategy for thermoresponsive aerogels that dynamically suppresses salt accumulation during solar evaporation by combining an asymmetric pore structure, thermoresponsive wetting switching, and ion-buffered transport.
The advancement of lightweight, high-performance ceramic matrix composites (CMCs) is of crucial significance for advanced aerospace hot-section components. Within these CMCs, the boron nitride (BN) interface assumes a crucial function in governing both microstructure and comprehensive performance. This research centers on porous mullite fiber-reinforced SiC (P-Mu/SiC) composites featuring a BN interface. It systematically explores how the oxidized BN interface regulates their microstructure, electromagnetic wave (EMW) absorption, and mechanical properties. The thickness and morphology of the B2O3-induced free-carbon layer within P-Mu/SiC composites can be regulated by manipulating the oxidation duration of the hexagonal BN interface. Additionally, the B2O3 phase was employed to further verify the induced mechanism of the free-carbon layer. When the oxidation duration is relatively short (t ≤ 4 h), a double-layer BN-C interface forms in the P-Mu/SiC composite, which is beneficial to optimizing both the EMW absorption and mechanical properties. When the oxidation duration is 4 h, a moderate BN-C interface enables the P-Mu/SiC composite to achieve effective EMW absorption (reflection loss ≤ −10 dB) in X-band at a thinner thickness. Meanwhile, the double interface can promote crack deflection and energy dissipation, resulting in an improved flexural strength of 32 MPa. These findings demonstrate that a B2O3-induced free-carbon interface enables synergistic enhancement of both EMW absorption and mechanical performance, providing a feasible design strategy for high-performance CMCs.
The proliferation of electronic devices and wireless communication technologies has generated an urgent demand for multi-frequency and multifunctional electromagnetic wave (EMW) absorption materials. In this work, we develop a novel MXene-reinforced hierarchical porous metal-organic framework (MOF)-derived sulfide@nitrogen-doped carbon nanofiber composite (PCN/MXene/ZnS@NC) via an electrospinning-assisted strategy combined with vapor sulfuration treatment. The resulting material exhibits a unique necklace-like architecture, in which MOF-derived metal sulfide nanoparticles are uniformly anchored onto the surface of MXene-embedded carbon nanofibers. This configuration generates abundant heterointerfaces and establishes an efficient three-dimensional conductive network, enabling the synergistic interplay of hierarchical porous architecture, dual mesopore distribution, and multiple polarization relaxation processes. The developed PCN/MXene/ZnS@NC composite inherits outstanding EMW absorption performance across the C-band, X-band, and Ku-band, with reflection loss (RL) values of −53.1, −55.9, and −58.3 dB, respectively, showcasing remarkable multiple-frequency compatibility (4.32, 10.88, and 15.92 GHz). Notably, the composite enables lightweight, flexibility, hydrophobicity, and rapid thermal response characteristics.
Materials with anisotropic thermal conductivity enable directional heat transfer and are of interest for advanced thermal management and transverse thermoelectrics. TaIrTe4 is a low-symmetry layered Weyl semimetal with an elongated unit cell. While its electronic topology and nonlinear transport phenomena have been extensively explored, the role of such structural complexity in governing anisotropic thermal transport remains unclear. Here, we experimentally determine the full thermal conductivity tensor of TaIrTe4 using frequency-domain thermoreflectance combined with a transducerless beam-offset method. Unlike the nearly isotropic in-plane thermal conductivities found in isostructural materials such as WTe2 and MoTe2, TaIrTe4 exhibits unusually strong in-plane anisotropy with a ratio of ∼3, among the highest values reported for layered materials. Temperature-dependent thermal conductivity and electrical resistivity measurements indicate that, despite being a semimetal, umklapp phonon scattering dominates heat transport. First-principles calculations reveal that the giant thermal anisotropy originates from extended structural motifs along a specific axis, which induce folding of the phonon spectrum. Because of the Cs symmetry of the wavevector group, this folding triggers frequent phonon hybridization and avoided crossings, resulting in phonon softening and a reduction of group velocities along specific directions. These findings uncover a distinct mechanism for anisotropic heat transport in complex semimetals and provide a strategy for the manipulation of phonon transport in low-symmetry materials.
Cadmium sulfide (CdS) as a classic visible-light-driven photocatalyst for renewable hydrogen production, yet its practical application is severely hampered by intrinsic photocorrosion stemming from the cleavage of surface Cd-S bonds. Herein, we report a surface coordination passivation strategy via metal cation modulation to stabilize sulfur sites of CdS. The constructed Co-S coordination interface endows CdS with significantly improved photocatalytic activity and structural durability during photocatalytic hydrogen evolution coupled with selective lactic acid dehydrogenation to pyruvic acid, with a selectivity exceeding 80%. Compared with pristine CdS (3.39 mmol g−1 h−1), the optimized Co-CdS exhibits a substantially enhanced hydrogen evolution rate of 11.47 mmol g−1 h−1 and achieves long-term stability over 120 h with negligible activity decay. Further modification with Pt cocatalysts efficiently accelerates charge separation, further elevating the hydrogen evolution rate to 22 mmol g−1 h−1 and delivering an apparent quantum yield of 18% at 450 nm. This work provides a facile and effective surface coordination engineering strategy to simultaneously boost the activity and anti-photocorrosion stability of metal sulfide photocatalysts toward solar-driven green hydrogen production coupled with selective organic transformation.
Reliable and flexible early fire warning sensors play a crucial role in fire detection, yet remain a major challenge. Herein, we combined poly (p-phenylene benzobisoxazole) (PBO) nanofibers with thermoelectric and thermochromic (PTT) nano-functional particles to construct a dual-mode early fire warning sensing fiber, which realizes accurate temperature detection through visual and digital signal cooperative sensing. The resulting core-sheath structured nanoscale PTT sensing fiber features PBO nanofibers as sheath, with perovskite crystals assembled on the outermost layer, while the core is composed of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)@tellurium nanowires (Te NWs)/polyurethane composite thermoelectric nanomaterial. Incorporating PEDOT:PSS@Te NWs into the core facilitates a millisecond-level response to fire (threshold voltage: 1.0 mV, response time: <= 0.9 s) and wide temperature range (50-300 degrees C) fire warning performance. This rapid response is attributed to the optimization of the Te NWs nanointerface heterojunction structure, as well as the formation of a nanowire permeable conductive network, which synergistically enhances the Seebeck coefficient and conductivity (S = 46.5 mu V K--(1), sigma = 2.05 & times; 10(4) S m(-)(1)). Moreover, the sensing fiber has achieved an independent power-free visual warning capability by utilizing colorimetric monitors and the thermochromic properties of perovskite crystals over a wide temperature range of 100-300 degrees C. This work offers a novel approach to develop a reliable real-time monitoring strategy with an impressive temperature sensing accuracy of up to 97.25% to early fire warning detection in precombustion. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & ( http://creativecommons.org/licenses/by/4.0/ )
Crack control remains a major challenge in laser-directed energy deposition (LDED) of oxide eutectic ceramics because of their intrinsic brittleness and thermal-stress accumulation. In this work, emissivity-calibrated in-situ infrared thermometry and thermo-mechanical simulation were used to reveal how circular oscillation scanning (COS) reduces the crack susceptibility of LDED Al2O3/GAP/ZrO2 eutectic ceramics. Compared with linear reciprocating scanning, COS produced a wider high-temperature zone, stronger interlayer reheating, and milder recooling. At the representative mid-height location, the average cooling rate from peak temperature to melting point decreased from 330.91 to 173.82 °C/s, while the reheating-induced temperature rise increased from 167.38 to 1076.03 °C. Stress analysis showed that COS reduced crack susceptibility mainly by weakening the continuous bottom-centered tensile-stress band and localizing higher-stress regions near the side areas, rather than by simply lowering the local stress peak. This stress redistribution was consistent with the observed transition from bottom-initiated vertical cracking to side-localized, laterally limited cracking. The COS parameter study further revealed a trade-off between thermal coverage and tensile-stress concentration. These findings provide guidance for scan-path design and crack control in LDED of oxide eutectic ceramics.
Resolving the intrinsic conflict among optical transparency, mechanical robustness, environmental adaptability, and conductivity remains a formidable challenge for hydrogel-based ionotronics. Herein, a novel “Solvent-Ion Synergistic Engineering” strategy is proposed to construct a hierarchical triple-network hydrogel (GAAE-Zr) that successfully overcomes these trade-offs. The design integrates a covalently crosslinked poly(acrylamide-co-2-acrylamido-2-methylpropanesulfonic acid elastic backbone, dynamic Zr4+ coordination bonds for toughening without coloration, and an ethylene glycol/water binary solvent system for anti-freezing and anti-dehydration. Through this architecture, the resulting hydrogel exhibits exceptional toughness (elongation > 1500%, tensile strength 286 kPa) and broad-spectrum adhesion, while maintaining glass-like transparency (> 90%). Simultaneously, the reconfigured hydrogen-bonding network significantly depresses the freezing point to −49.5 °C and locks in moisture for long-term stability. Leveraging these merits, the GAAE-Zr hydrogel is demonstrated as a high-fidelity strain sensor with stable conductivity (up to 0.74 S/m) for thermally stable wireless human-machine interaction, and is further implemented as a fully encapsulated triboelectric nanogenerator delivering an instantaneous power density of 220 mW m−2. This work establishes a versatile material platform and a new design paradigm for next-generation wearable electronics requiring multifunctional integration and all-weather operational reliability.
A systematic study on δ-Ni3Nb intermetallic compound growth and microstructural evolution was conducted in Ni-Nb alloys using the electromagnetic levitation technique, with the aim of elucidating their correlation with tribological properties. The Ni84Nb16 eutectic and Ni66.7Nb33.3 hypoeutectic alloys were undercooled to the maximum undercooling of 200 K (0.13TL) and 250 K (0.15TL), the corresponding growth velocities of (γ + δ) eutectic and primary δ-Ni3Nb dendrite were 2.75 m/s and 2.65 × 10−2 m/s, respectively. As undercooling increased, the growth of the δ-Ni3Nb phase promoted by the rapid coupled growth of the (γNi) phase in the Ni84Nb16 alloy transitioned from growth along close-packed directions in lamellar eutectic to rapid growth along non-close-packed directions with pronounced faceted characteristics in anomalous eutectic. By contrast, the primary δ-Ni3Nb phase in the Ni66.7Nb33.3 alloy preferentially grew along close-packed directions, forming a rod-like morphology. Compared with the master alloy, the wear mechanism of the Ni84Nb16 alloy transformed from fatigue wear to oxidative wear, resulting in a 66% decrease in the specific wear rate (to 1.76 × 10−6 mm3/(N m)) at the maximum undercooling. This improvement was attributed to decreased anisotropy within eutectic colonies plus microstructural refinement. For the Ni66.7Nb33.3 alloy, the specific wear rate was reduced by 12% (1.68 × 10−6 mm3/(N m)) at the maximum undercooling, owing to the increased volume fraction of the primary phase and microstructural refinement.
Carbon-based single-atom catalysts (SACs) offer exceptional atom utilization efficiency and tunable active sites; however, the precise engineering of intrinsic carbon defects, such as vacancies and edges, without heteroatom interference remains a significant challenge. Herein, we developed a magnesium-assisted strategy for fabricating platinum single-atom electrocatalysts anchored solely on intrinsic carbon defects (denoted as PtSACs-C-1100), utilizing a nitrogen-free Mg-gallate MOF as a precursor. During pyrolysis at 1100 °C, uniformly dispersed Mg2+ sites serve as in situ etchants to create a hierarchical porous network rich in structural defects. Spectroscopic and theoretical analyses confirmed that the Pt atoms anchored at the defect sites form Pt-C2 coordination configurations. This unique structure optimizes the hydrogen adsorption energy (∆GH* = 0.0391 eV), endowing the catalyst with exceptional activity for the hydrogen evolution reaction (HER: η10 = 16.5 mV in acid and 50 mV in alkali). With a Pt loading of 4.4 wt%, PtSACs-C-1100 exhibits higher mass activities 6.6–9.4 times higher than those of commercial 20 wt% Pt/C. Moreover, PtSACs-C-1100 also shows excellent oxygen reduction reaction activity (E1/2 = 0.866 V). When deployed in a flow Zn–air battery, it achieves a peak power density of 230.8 mW cm−2 and sustains stable operation for > 200 h, demonstrating practical viability for energy conversion devices.
Developing advanced intelligent materials that integrate long service life, high reliability, and sustainable recyclability remains a critical unresolved challenge in the field of high-end equipment. Conventional polyurethanes, constrained by their intrinsic molecular structures, struggle to reconcile mechanical performance with self-healing capability. Guided by a molecular-nanoscale multiscale structural design paradigm, this study designs and fabricates a novel polyurethane composite through a ternary synergistic strategy involving dynamic covalent bonds, multiple hydrogen bonds, and rigid nanotubes. Incorporation of dynamic disulfide bonds and guanidine-functionalized halloysite nanotubes (M-HNTs) enables the construction of a reversible adaptive chemo-physical network architecture. Through the cleavage and recombination of dynamic disulfide bonds and multiple hydrogen bonds, this material exhibits robust self-healing capability (efficiency > 94%), excellent wear resistance (wear rate 2.6 × 10−14 mm3/(N m)), and remarkable recyclability (> 90% mechanical retention after 6 cycles), along with good shape memory function (recovery rate > 96%). This work provides theoretical guidance for the design of multifunctional intelligent materials tailored to high-end equipment applications, addressing the intrinsic trade-offs between key performance metrics in functional polymeric composites.
Heterogeneous structural design is an effective strategy for achieving breakthroughs in the mechanical properties of dissimilar material joints. In this study, a cold spray-assisted brazing technique was proposed to significantly improve the strength of Cf/C-Nb brazed joints by fabricating a dense and uniform Ti-Co-TiC composite interlayer. Research indicates that TiC particles promoted the reconstruction of the brazing seam through heterogeneous nucleation and Zener pinning effects, effectively disrupting the continuous Ti2Co brittle network and constructing a strong-tough interpenetrating structure composed of a ductile β-Ti(s, s) and hard phases. The semi-coherent interfaces (lattice misfit of 6%–8%) formed between TiC and the β-Ti(s, s)/α-Ti phases were accompanied by significant localized strain gradients, leading to the enrichment of geometrically necessary dislocations (GNDs) nearby. This contributed to the accommodation of interfacial strain distribution. The dispersed TiC particles induced crack path deflection and branching by altering the local stress field, increasing energy dissipation during propagation. Combined with the plastic blunting effect of the ductile β-Ti(s, s) phase, a cross-scale synergistic strengthening was achieved. The peak shear strength of the Cf/C-Nb joints using the cold-sprayed interlayer reached 50.1 MPa, compared to 5.6 MPa for conventional powder-brazed joints. This study demonstrates the significant potential of cold spray-assisted brazing in regulating the performance of joints with extreme thermal expansion mismatches, offering a new microstructural construction strategy for high-performance brazed joints.
Additive manufacturing (AM) of face-centered cubic (FCC) metals offers unprecedented geometric freedom and often yields exceptional mechanical performance, largely due to the formation of dislocation-rich cellular substructures. However, rational strategies to reconfigure these nonequilibrium architectures for further property enhancement remain limited. Here we show that controlled thermal cycling inherent to multipass AM can be exploited to engineer subgrain-scale hierarchical structures in a CoCrNi medium-entropy alloy. Recurrent thermal exposure during deposition transforms dislocation cell walls into a percolating network of low-angle grain boundaries, while simultaneously promoting dense stacking-fault activity both along cell walls and within cell interiors, and triggering stress-assisted nanotwin formation. This hierarchical subgrain architecture establishes a dense, interconnected barrier network that significantly enhances yield strength and strain hardening capacity. Moreover, the homogeneous three-dimensional distribution of these barriers mitigates mechanical anisotropy by promoting more uniform plastic flow. Together, these results establish a subgrain-level design principle for FCC alloys, providing a general pathway towards high strength, ductility, and mechanical isotropy.
