Nanomaterials最新文献

Magnetic metals are of considerable importance for stealth technology and electromagnetic pollution control. However, they suffer from inherent limitations, such as the Snoek limit and narrow absorption bandwidth, which restrict their applications in complex scenarios. To address these challenges, this review systematically summarizes the recent advances of magnetic metal-based microwave-absorbing materials (MAMs), focusing on four core directions: alloy design, composite engineering, structural regulation, and preparation technology. The intensity and frequency bands of absorption in alloys are dictated by the material's composition as well as its structural attributes. Moreover, composite systems incorporating carbon materials, MXenes, oxides, ceramics, and conductive polymers are discussed, where the synergistic design of components optimizes impedance matching and loss mechanisms. Key structural design strategies include core-shell structures, interface engineering, self-assembled hierarchical structures, and macroscopic structural design. These structures achieve the synergistic improvement of thin, lightweight, broadband, and strong absorption performance by enhancing interface polarization, multiple scattering, and resonance effects, while endowing materials with excellent environmental stability. Notably, metamaterial-based designs can further achieve an ultrawide bandwidth spanning 0.3-18 GHz. Additionally, preparation processes are crucial for regulating the microstructure and activating loss mechanisms. This review aims to offer theoretical and practical insights for developing high-performance, multifunctional magnetic MAMs.

Suppressing the polysulfide shuttle effect and accelerating the sulfur redox kinetics remain pivotal challenges for advancing the practical viability of lithium-sulfur batteries (LSBs). In this study, an iodine-doped carbon nitride (I-CN) material was synthesized via a one-step annealing strategy and employed as a metal-free sulfur cathode host. Compared to its pristine counterpart, I-CN exhibits a substantially increased specific surface area, which facilitates the homogeneous dispersion of sulfur species. More importantly, the incorporation of iodine atoms disrupts the equilibrium of the electron cloud distribution within the CN framework, leading to enhanced electron delocalization. This electronic modulation not only significantly improves the charge transport properties of carbon nitride but also strengthens the adsorption of lithium polysulfides (LiPS) and promotes Li₂S nucleation, thereby enabling fast and durable sulfur redox reactions. Benefiting from these synergistic effects, the S@I-CN electrode achieves high sulfur utilization, delivering an initial discharge capacity of 1341.9 mAh g^-1 at 0.1C. Even at a high current density of 5C, a remarkable reversible capacity of 472.7 mAh g^-1 is retained. Notably, the electrode retains 66.2% of its initial capacity after 800 cycles, demonstrating excellent long-term cycling stability. This halogen-based heteroatom doping strategy thus not only enhances the electrochemical performance of carbon nitride materials in LSBs through the rational manipulation of electron delocalization, but also offers a promising direction for the design of novel metal-free electrocatalysts in related energy conversion systems.

This study investigates the irradiation response of two L1₂-strengthened HEAs, (Ni₂Co₂FeCr)₉₂Ti₄Al₄ (TiHEA) and (Ni₂Co₂FeCr)₉₂Nb₄Al₄ (NbHEA), subjected to 6.4 MeV Fe³⁺ irradiation at 500 °C up to 30 dpa. Transmission electron microscopy (TEM) and atom probe tomography (APT) consistently showed that the Ti-containing HEA maintains L1_2-ordered structure and compositional stability better than Nb-containing alloys under irradiation. This difference is attributed to the distinct solute-defect interactions. Ti imposes a weaker hindering effect on vacancy mobility, allowing vacancies to remain mobile and participate in thermal reordering processes that counteract ballistic mixing, whereas Nb acts as a strong vacancy trap, suppressing the diffusion required for structural recovery. Irradiation-induced dislocation loops in the two alloys further exhibited different characteristics. TiHEA showed larger loops at lower number density, and NbHEA exhibited a higher density of smaller loops, consistent with their respective stacking fault energies and loop mobility. Nanoindentation results indicated that TiHEA exhibited a slightly higher irradiation hardening rate (27%) than NbHEA (23%), likely associated with a stronger order-strengthening contribution, given the better preservation of precipitate order in TiHEA under irradiation. These findings show the critical role of solute addition in designing radiation-tolerant high-entropy alloys.

Carbon nanotube (CNT) cathode materials exhibit excellent electron emission performance and have become a key research focus in the field of vacuum electronics. However, their practical applications are still restricted by challenges, including emission instability and ambiguity in temporal resolution capability. This work investigated the thermal-assisted field emission characteristics of CNT and their application in pulsed X-ray imaging. Systematic characterization of the turn-on field strength, emission stability, pulse response characteristics, and pulsed X-ray imaging performance demonstrated that the thermal-assisted operating mode reduced current fluctuations to below 1%. Increasing the heating power further enhanced emission stability and lowered the turn-on field strength. In thermal-assisted pulsed emission mode, CNT cathodes exhibited reduced power consumption compared to conventional thermionic cathodes and achieved microsecond-scale pulse response. Further X-ray imaging experiments confirmed that the X-ray dose generated by CNT in this operational mode exhibited higher stability, enabling 100 μs pulsed imaging and clear visualization of rotating blades operating at 600 Hz. This study validated the feasibility of CNT cathodes for high-speed X-ray imaging and could provide a reference for the development of advanced pulsed X-ray sources and related technologies.

Lightweight, efficient, and reversible hydrogen storage materials are critical for the advancement of hydrogen-based energy technologies. In this work, we present a comprehensive density functional theory (DFT) investigation of hydrogen storage in pristine and metal-decorated C₈ carbon quantum dots (CQDs), representing ultrasmall, highly curved nanomaterials at the molecular-nanoscale interface. Lithium, magnesium, and titanium were investigated as representative decorating metals to tailor hydrogen adsorption strength and reversibility. The pristine C₈ quantum dot is structurally stable but exhibits negligible hydrogen affinity (-0.062 eV per H₂), rendering it unsuitable for practical storage applications. In contrast, metal decoration significantly enhances hydrogen adsorption while preserving molecular H₂ physisorption, yielding optimal single-molecule adsorption energies of -0.172, -0.304, and -0.451 eV for Li-, Mg-, and Ti-CQDs, respectively. Sequential adsorption analysis indicates exceptionally high hydrogen uptakes of up to 18 H₂ molecules for Li-CQD and 20 H₂ molecules for both Mg- and Ti-CQDs, corresponding to very high theoretical gravimetric capacities. Energy decomposition and interaction region analyses demonstrate that hydrogen uptake proceeds via a cooperative physisorption mechanism driven by dispersion, electrostatic, and polarization interactions, strongly enhanced by quantum confinement and extreme curvature effects inherent to the CQD. Grand canonical thermodynamic modeling confirms fully reversible hydrogen storage under practical temperature and pressure conditions. Among the systems studied, Mg-CQD exhibits the most favorable balance between adsorption strength and desorption accessibility, delivering a remarkable reversible gravimetric hydrogen storage capacity of 21.7 wt%, significantly surpassing most metal-decorated graphene-, fullerene-, and carbon nanotube-based materials reported to date. These results establish metal-decorated C₈ quantum dots as a new class of high-performance nanomaterials for reversible hydrogen storage and demonstrate the potential of ultrasmall carbon quantum dots to overcome the long-standing trade-off between hydrogen uptake and reversibility in nanostructured storage media.

This study aimed to synthesize silver nanoparticles (AgNPs) using an eco-friendly method with Ocimum lamiifolium leaf extract as a natural reducing agent. The research examined how different conditions affected nanoparticle stability and size. Characterization techniques included XRD, SEM, FTIR, UV-vis spectroscopy, particle size analysis, PDI, and zeta potential. A color change from colorless to grey indicated successful reduction of Ag⁺ to Ag°. UV-vis spectra showed a peak at 467 nm, confirming nanoparticle formation. The average size was 65 nm with a PDI of 0.241, indicating uniformity, and the zeta potential was -13.4 mV, suggesting good stability. The functional groups of phytochemicals involved in reduction and stabilization were identified by FTIR analysis. A face-cantered cubic crystalline structure was verified by XRD. Higher AgNPs concentrations resulted in larger zones of inhibition in antibacterial tests against E. coli, ranging from 4 mm to 15.45 mm. Reduction, stabilization, membrane rupture, ROS generation, and bacterial cell death were all steps in the green synthesis process. Overall, the stability and antibacterial activity of AgNPs made with Ocimum lamiifolium extract were outstanding, highlighting the potential of plant-based approaches for biomedical applications.

Two decades after the first bold proclamations that nanomedicine would deliver "magic-bullet" therapies capable of cell-level targeting, the field stands at a crossroads. While some initial promises (improved delivery of poorly water-soluble drugs and enhanced efficacy and biocompatibility of nano-based devices) have been fulfilled, other early promises (active targeting, biodegradability, multifunctionality, triggered responses, real-time data output, and implantable sensors) remain only partially realized. This article will compare the properties of approved nano-based products to those of the ideal products, assess the shortcomings of existing nano-based products, and discuss critical issues in nanotoxicity (biodistribution and protein corona effects, immune interactions, and biopersistence) and the lack of data on product and end-of-life life cycle analyses. The role of in silico tools in the various steps of nanodrug and nano-based device development and manufacturing-areas in which these tools are the most established (nanocarrier design, prediction of cellular effects, chemical composition optimization, manufacturing, and signal interpretation)-is also addressed. Future goals include biodegradable targeted delivery systems, better tissue integration of implants, and implantable sensors. It is expected that, alongside careful physicochemical characterization of the nanoproduct, toxicity testing focused on nano-specific effects and life cycle analyses of production and end-of-life phases will facilitate the approval of nano-based products.

Polypyrrole-based functional composites are increasingly explored and extensively adopted for energy storage, sensing, and environmental applications due to their tunable electronic properties, chemical versatility, and mechanical stability. However, rational optimization of these composites requires a unified understanding of electronic, mechanical, thermal, and chemical behavior at the atomic scale, which underlies their multifunctional behavior, and remains fragmented. Notably, Density Functional Theory (DFT) provides indispensable atomistic insight into the electronic, mechanical, thermal, and chemical interactions that govern the performance of multifunctional materials. To bridge these gaps, this review presents a comprehensive assessment of recent DFT and time-dependent DFT (TD-DFT) studies that elucidate the electronic, mechanical, thermal, and chemical characteristics of polypyrrole and its hybrid composites. Key theoretical descriptors, including electronic structure modulation, charge transfer behavior, adsorption energetics, interfacial binding energies, hydrogen bond formation, and charge redistribution, are critically assessed to establish structure-property relationships across diverse functional systems. Considerable attention is given to interfacial interactions, doping strategies, and composite architectures that govern durability, conductivity, and chemical stability. By consolidating current atomistic insights and identifying existing limitations, this review provides a coherent framework for rational material design. Notably, it presents the first systematic quantification of dopant steric effects in PPy multifunctional composites, linking atomistic-scale modifications to the optimization of functional properties in next-generation applications.

Integrating functional perovskites on an amorphous microchannel plate (MCP) glass faces challenges regarding the lack of ordered nucleation sites and stringent thermal budgets. Herein, we propose a surface energetics-based atomic layer deposition (ALD) strategy to achieve template-assisted oriented BaTiO₃ growth via a (101)-oriented anatase TiO₂ seed layer. Systematic investigation of the TiCl₄/O₃ process reveals a kinetic-to-thermodynamic transition at 300 °C, triggering a singular (101) preferred orientation. Combined DFT calculations and Wulff construction elucidate that this texture evolution is governed by a thermally activated surface energy minimization mechanism, driven by the intrinsic stability of the (101) facet. Crucially, the optimized seed layer acts as a multifunctional template: it not only transforms BaTiO₃ growth from random polycrystalline morphology to a singular (100) orientation with suppressed bulk carbonate impurities but also ensures excellent conformality and uniformity throughout the high aspect ratio microchannels. This study clarifies the thermodynamic mechanism of oriented growth on amorphous substrates, providing a versatile surface engineering pathway for constructing high-performance MCP-based heterojunction devices.

CrAlSiN nanocomposite coatings with different structures were prepared by arc ion plating. The influence of substrate bias on the composition, microstructure and properties of the coating was investigated. The nanocomposite CrAlSiN coatings all had a fcc-(Cr, Al)N phase, where Al atoms and some Si atoms were solid-dissolved in CrN phase and some Si existed in the form of amorphous phase in the coating. The coatings were preferentially grown along the (200) crystal plane. With the increase in substrate bias, the roughness of the coating gradually decreased. When the substrate bias gradually increased to 100 V, the small particles aggregated into large particles, producing more holes, so that the surface roughness of the coating increased. At the same time, with the increase in substrate bias, the hardness and adhesion of the coating first increased and then decreased. When the substrate bias voltage was 80 V, the coating had the largest hard H (31.30 GPa), elastic modulus E* (432.15 GPa), H/E* (0.0724), H³/E*² (0.1642) and binding force of 109.26 N.