Carbon Letters最新文献

This study investigates the repeated impact behavior and compression-after-impact (CAI) performance of triaxially braided carbon/glass fiber-reinforced polymer (C/GFRP) composite tubes. A two-stage experimental strategy was proposed to evaluate the synergistic effect of interlayer hybridization and axial yarn reinforcement on damage evolution and mechanical performance. In Stage I, six hybrid braided tubes with different carbon/glass stacking configurations—including pure carbon, pure glass, layered, and reversed-layered structures—were subjected to repeated low-velocity impacts at 31 J. Micro-CT was employed to reconstruct the internal damage morphology and assess damage accumulation. The optimal interlayer configuration was selected based on impact force, displacement, energy absorption, and internal failure characteristics. In Stage II, the selected structure was further reinforced with four types of axial yarns (none, carbon, glass, and carbon/glass alternating), and their axial compressive and CAI performance after 10 J impact was tested. Results revealed that reversed interlayer design effectively suppressed crack propagation and improved damage tolerance under cyclic impacts. Moreover, the inclusion of hybrid axial yarns significantly enhanced residual compressive strength without compromising energy absorption. This study establishes a lightweight, high-performance braided tube design strategy suitable for aerospace and transportation applications.

Carbon nanotubes (CNTs) have been widely applied in diverse fields due to their exceptional mechanical, electrical, and thermal properties. However, the growing demand for precise control over their structure, crystallinity, and yield is severely hindered by the intricate, multi-factor-influenced CNTs growth process—this has become a critical bottleneck limiting their further application. A key breakthrough in addressing this challenge is the discovery that CNTs growth follows the "synergistic action of matter-driven and energy-driven" mechanisms. Mastering these dual driving mechanisms, establishing the direct link between reaction conditions and product structures, and thereby optimizing reaction paths, emerges as an effective strategy to achieve precise regulation of CNTs nucleation and growth. Against the backdrop of industrialization, this review not only provides a critical theoretical basis for breaking through the bottleneck of precise growth control but also directly propels high-quality CNTs toward broader and more practical application prospects.

Carbon nitride (C₃N₄) is a class of nanomaterials that recently became increasingly important in the field of health and biomedicine. However, there is a lack of data regarding its toxicity and how this type of material affects the cells of the innate immune system, such as macrophages. The objective of this study was to evaluate and compare the effect of C₃N₄ in its pristine and oxidized (oxC₃N₄) forms using a monocytic cell line differentiated into macrophages. Human THP-1 cells, differentiated into macrophages, were exposed to increasing concentrations of C₃N₄ and oxC₃N₄ (e.g., 10, 50 and 100 µg/mL). The assessment of the overall cytotoxicity, by quantifying intracellular adenosine triphosphate (ATP), apoptosis, change of mitochondrial membrane potential and generation of reactive oxygen species (ROS), was carried out. The results showed a significant decrease in cellular ATP after 48 and 72 h of exposure to both type of nanomaterials. The subsequent staining with annexin V and propidium iodide confirmed a significant increase in cell death induced by oxC₃N₄, but not by pristine C₃N₄. A significant decrease in mitochondrial membrane potential was also observed only when macrophages were exposed to C₃N₄, raising question about the presence of a cell death mechanism not involving mitochondria and masking apoptosis in the case of the oxidized carbon nitride. In addition, in the non-cytotoxic condition, oxC₃N₄ was able to induce ROS generation. Taken together, our results show that the oxidized form of C₃N₄ is that affecting more the viability of macrophages.

The co-sintered phosphor of cerium-doped yttrium aluminum garnet (YAG:Ce) and aluminum nitride (AlN) is a promising material for next-generation light-emitting diode lighting applications. Despite AlN’s excellent thermal conductivity, its high sintering temperature and surface reactivity limit its industrial use in co-sintered phosphors, and effective methods to improve its sinterability without compromising properties remain underexplored. In this study, the sinterability of the AlN and YAG:Ce composite is improved by coating AlN particles with a soluble carbon material (SCM) prior to sintering. SCM coating leads to a 6.75% increase in photoluminescence (PL) intensity under 15 W laser excitation and a 6.85% improvement in thermal conductivity, which suppresses thermal quenching. The enhanced thermal conductivity also minimizes PL decay over time, thereby maintaining high luminosity for extended periods. Furthermore, the hardness and handling properties of the obtained sintered body are significantly improved, with hardness increasing by 112.3% when SCM-coated AlN is used. Notably, the SCM does not remain in the final product, as it is fully removed during sintering, leaving no impurities or adverse effect on the material’s properties. Given its ability to easily and uniformly coat ceramic particles, SCM coating holds promise for broader application in enhancing the sinterability and performance of various ceramic-based materials.

Carbon fibers (CFs) are notable for their lightweight, high strength, and excellent electrical conductivity, making them promising for applications like electrical wiring. However, integrating CFs into copper-based wiring systems faces challenges, particularly regarding conductivity loss in fractured CFs. This article discusses a two-step experiment to enhance electrical and mechanical connection. Electrothermal-induced solvent evaporation (EISE) and meniscus-confined electrochemical deposition (MECD) were identified as effective methods for welding fractured CFs and were successfully implemented in open-air environment. Deposition of carbon nanotubes (CNTs) around the fiber improved conductivity by reducing fiber-to-fiber contact resistance and creating a metal-like surface. Microstructural analysis and EDS analysis revealed that the CNT cladding exhibited high density and fewer irregularities and bulges in the joint area. Furthermore, the CNTs were tangled, forming a less organized structure compared to the original CF. In contrast, the Cu cladding exhibited paint-like coverage, significant irregularities, bulges, and cracks but maintained a small thickness. Electrical testing revealed that the average resistance of a single joined fiber decreased to resistance of 11.45 Ω and an electrical resistivity of 2.27 Ω/m, demonstrating improved electrical conductivity. Under optimal conditions, the joined fibers exhibited plastic fracture, and all joints showed improved performance except joint 1.e-g enhanced mechanical strength and stress tolerance.

Carbon fiber reinforced polymer (CFRP)/titanium alloy (Ti) stacks have become a research focus in aerospace and advanced manufacturing due to their superior integrated properties. However, interfacial characteristics and interlayer gaps critically influence cutting forces and hole-making quality. So, a cutting simulation model for CFRP/Ti stacks with interlayer gaps is established, the cutting force variation with interlayer gaps during milling and the mechanistic role in interfacial defect formation are deciphered through multiscale simulations. In addition, the correctness of the simulated model is verified by helical milling experiments, and the influence of machined surface quality under different clearance conditions is also evaluated. The results reveal a four-stage nonlinear evolution pattern of interfacial cutting forces during helical milling of CFRP/Ti stacks with gaps. Further investigation indicates that this nonlinear evolution pattern results in the development of localized damage evolution regions adjacent to interlayer gaps in CFRP composites, especially. A characteristic stepped distribution pattern is observed in both hole-wall topography and burr dimensions within the affected zones.

Multimodal composites have the potential to play a crucial role in the development of theranostic agents. Systems with optical and magnetic response can be applied in medicine for both imaging and therapy; however, combining magnetic and luminescent nanoparticles in one entity is challenging. Both the morphology and architecture of the composite, as well as the influence of the magnetic components and matrix on the light-emissive component, must be paid attention. In this study, we demonstrate a design of a composite with advantageous magnetic response and luminescence in green and red regions (excited at 405 and 580 nm, respectively), where biocompatible CaCO₃ microspheres were loaded and decorated with luminescent carbon dots (CDs) and magnetite nanoparticles (MNPs). We showed the absence of CDs’ toxicity by the IC50 tests and demonstrated its localization in L1 and L4 stages of C. elegans embryogenesis. We determine the optimal parameters for composite formation to achieve their improved performance and structural stability. The composites were fabricated in several steps, including loading nanoparticles and layer-by-layer application of polyelectrolytes on top of CaCO₃. We demonstrated the applicability of the prepared composite microspheres for flow cytometry and showed their potential as multiplexed visualization agents, emphasizing their potential use as promising theranostic agents.

Graphical Abstract

Composites with multicolor emission and magnetic response have been obtained using vaterite microspheres loaded and decorated with carbon dots and magnetite nanoparticles via freeze-induced loading and layer-by-layer polyelectrolyte coating. Optimal optical and magnetic properties of these composites have been achieved by varying the order of component loading and the interparticle distance.

In this study, an anode composite material was fabricated by embedding spherical carbon-coated nanosilicon (Si@C) into a layered carbon-coated silicon (L-Si/C) to enhance the capacity and stability of silicon-based lithium-ion batteries. The L-Si/C material was obtained by reacting CaSi₂ through a CO₂-assisted carbonization process, followed by removal of the CaCO₃ byproduct via HCl etching. Si@C particles, prepared using polydopamine as a carbon precursor, were uniformly embedded in the L-Si/C via ultrasonic treatment. The physical properties of the prepared anode composites were analyzed using HR-SEM, EDS, XRD, and BET. The electrochemical performances were investigated using 1 M LiPF₆ in EC:DEC (1:1 vol%) with 10 wt% FEC as the electrolyte, through charge–discharge cycling, rate capability tests, electrochemical impedance spectroscopy (EIS), and differential capacity (dQ/dV) analysis. L-Si/C exhibited the best electrochemical performance under the thermal treatment condition of 720 °C and a CO₂ flow rate of 100 sccm. In addition, the application of ultrasonic treatment improved structural stability and rate capability. Consequently, the S_L-Si/C + Si@C-2 exhibited a high initial discharge capacity of 2700.7 mAh/g at 0.1 C and a capacity of 617.4 mAh/g at a high rate of 6 C.

Sodium-ion batteries (SIBs) have emerged as a promising alternative to lithium-ion batteries due to the natural abundance and low cost of sodium resources. However, the relatively large ionic radius of sodium ions hinders their intercalation into conventional graphite anodes, necessitating the development of advanced anode materials. In this study, high-performance hard carbon materials were synthesized from ZIF-8 precursors through controlled carbonization at various temperatures. Among the samples, ZIF-800, which is carbonized at 800 °C, exhibited the highest reversible capacity (156.63 mAh/g after 100 cycles at 100 mA/g) and excellent cycling stability. This superior performance is attributed to the optimized combination of high specific surface area (700.35 m²/g), well-developed pore structure, and enhanced defect concentration, as indicated by a low I_G/I_D ratio. The capacitive-dominant charge storage behavior further contributes to the improved electrochemical characteristics. These findings highlight the critical role of tuning carbonization temperature to achieve a balanced microstructure, offering valuable insights for the rational design of high-performance hard carbon anodes for SIBs.

Doping diamond exhibits excellent photoelectric properties, making it promising for applications in wide-bandgap semiconductors, high-temperature devices, and high-power electronics. However, research on n-type doping remains limited. This paper reviews the main n-type doping methods for diamond: ion implantation (I/I), chemical vapor deposition (CVD), high pressure–high temperature (HPHT), deuterated method (DM), surface charge transfer doping (SCTD), and laser irradiation (LI). It analyzes the parameters, advantages, and disadvantages of each technique while classifying common single-element and multi-element co-doping methods. Single-element dopants include Group IA (Li, Na, K), Group ⅡA (Be, Mg), Group VA (N, P, As, Sb), and Group ⅥA (O, S, Se, Te) elements. Multi-element co-doping often combines B-P, B-S, B-O, and B-N pairs. Additionally, we examine the atomic structures of these dopants, introduce commonly used simulation models, and compare the electronic characteristics of synthesized n-type doping diamonds. Finally, we summarize the challenges of n-type doping diamond in doping equipment, processes, and electronic devices, and propose possible improvements and future development directions.