Carbon最新文献

Ultra-thin and lightweight excellent electromagnetic wave (EMW) absorption materials have seen increased attention due to their potential to address electromagnetic pollution. Combining heterointerface engineering and an intrinsic interfacial polarization response has resulted in material development that has demonstrated improved EMW absorption capabilities, yet the underlying mechanisms are not well understood. Herein, we construct a three-dimensional (3D) N-doped reduced graphene oxide aerogel containing abundant heterointerfaces between ultrasmall Co and MnO nanoparticles (NrGO/Co–MnO aerogels), with Co and MnO particle diameters of ∼6.0 nm. These 3D NrGO/Co–MnO aerogels produce a reflection loss of −51.7 dB and an effective absorption bandwidth of 4.08 GHz, much higher than that of the single-phase aerogels. The density functional theory calculations and experimental results indicate that the strong interfacial polarization caused by the charge redistribution at Co/MnO heterointerfaces, defect-induced polarization, and the synergistic effect between dielectric and magnetic loss enhance the electromagnetic wave absorption property of the 3D aerogels. These findings provide important insights and a basis for creating effective EMW materials and highlight the promise of heterointerface engineering in nanomaterials.

SiO₂/C foams with carbon particles as raw material were prepared using emulsion template combined with SiO₂ sol-gel technology. One significant hurdle lies in achieving scalable and cost-effective fabrication of bulk materials endowed with customized porosity, along with an optimal blend of attributes such as high mechanical strength, super-hydrophilicity, thermal insulation, and effective absorption of electromagnetic waves. SiO₂/C foams with varied pore sizes and porosities were synthesized by manipulating the water-oil volume ratio in the raw materials. The impact of pore size and porosity on the compressive strength, thermal insulation, super-hydrophilicity and electromagnetic wave absorption property of SiO₂/C foam materials were thoroughly investigated. The gel reaction involving inorganic SiO₂ not only could fix the bubbles in situ and impart sufficient mechanical properties but also confer super-hydrophilic characteristics to the SiO₂/C foam materials. The SiO₂/C foams exhibited adjustable porosity levels ranging from 57 % to 78 %.The SiO₂/C foams, characterized by a uniform pore size of approximately 8.33 μm, demonstrated low thermal conductivity. Additionally, the compressive strength of SiO₂/C foam with a porosity of 57 % was measured at 3.5 MPa. For sample S4, the minimum reflection loss (RL_min) of −48 dB with an effective absorption bandwidth spanning 5.76 GHz, observed at a matching thickness of 2.2 mm. Due to their outstanding performances, characteristics, and the ease of scalable fabrication, the SiO₂/C foams developed in this study showcase significant potential for diverse applications.

Since the swift progress of current intelligent devices, supercapacitors with effective electromagnetic interference (EMI) shielding ability are attractive for the modern electronics industry. Herein, we proposed a core-shell structure design strategy to construct hybrid conductive network with multistage heterogeneous interfaces. The SiC nanowires (NWs) were deposited in situ on the carbon fabric with robust bonding, which were covered by highly conductive carbon nanotubes (CNTs), constructing an interconnected core-shell structured SiCNWs@CNTs with large specific surface area. Obviously, CNTs significantly enhanced the conductivity and electroactive surface area of the SiCNWs, which ensured that the obtained SiCNWs@CNTs electrode exhibited a high areal capacitance of 53.53 mF/cm² at 0.2 mA/cm². Meanwhile, the stable multistage structure with strong interface bonding conveyed excellent cycle stability (107.1 % capacitance retention after 5000 cycles at 10 mA/cm²). Moreover, due to the synergistic effect between SiCNWs and CNTs, the multistage heterogeneous structure with high conductivity and abundant interfaces enhanced the conductive and polarization loss. The integrated electrode possessed excellent EMI shielding performance of 47.99 dB in frequencies of 8.2–12.4 GHz. This research expands the horizons of the search for superior supercapacitors and EMI shielding performance, which will further benefit the advancement of SiCNWs-based composites for superior electronic devices.

Developing eco-friendly electromagnetic wave (EMW) absorption materials with simultaneous compression-resistant resilience, thermal insulation properties, and stability in complex environments is a formidable challenge. Inspired by the honeycomb structures, we utilized the concepts of directional freezing and carbonization to fabricated versatile P-doped hydrophilic carbon aerogel (CPA) for more demanding and complex applications. The numerous boundary-type defects generated by graphene nanosheets (GNs) and multi-walled carbon nanotubes (MWCNTs) on the surfaces of the honeycomb structure served as polarization centers, resulting in an effective absorption bandwidth (EAB) spanning from the C band to the Ku band (4–18 GHz, 1.0–4.0 mm) yielding a minimum reflection loss (RL, −72.02 dB) for CPA-800. The radar cross section (RCS) values of CPA-800 were below −15 dBm² within the range of −90° < θ < 90°, possessing a strong radar wave attenuation capability for potential application in both air and underwater conditions. The thermal insulation performance of CPA-800 reduced the sample temperature from 300 °C to 63 °C, and possessed outstanding structural stability during prolonged and intense flame exposure. This work represents a novel multifunctional platform for EMW absorption, thermal insulation, and resilience materials in various harsh environments.

Carbon fiber reinforced composites are sophisticated materials that are blends of carbon fibers (CFs) with a polymer matrix, providing outstanding strength, stiffness, and lightweight properties. Petroleum asphaltenes, the heavy fraction of bitumen, offer high aromaticity and carbon content, making them a cost-effective and promising raw material to produce high-value CFs. This study investigates the utilization and effectiveness of asphaltene-derived carbon fibers (ACFs) in composites produced through additive manufacturing. The composites were 3D printed by incorporating different weight proportions (0 %, 2.5 %, 5 %, and 7.5 %) of chopped ACFs (length 3–4 mm, diameter ∼6–12 μm, tensile strength ∼500–1150 MPa, tensile modulus ∼40–90 GPa) without any post-treatment (without surface functionalization and sizing). Extensive characterizations were carried out on both ACFs and their derived composites to evaluate their mechanical (tensile, flexural, hardness, impact, etc.) properties to identify potential applications. Furthermore, the reinforcement ability of ACFs was assessed in contrast to composites produced from expensive commercial carbon fibers derived from polyacrylonitrile. Incorporating 7.5 wt% ACFs into the acrylonitrile butadiene styrene (ABS) matrix enhanced ABS's flexural and tensile strengths by ∼20 % and ∼5 %, and its corresponding modulus values by ∼30 % and ∼34 %, respectively. In addition, ABS's hardness was improved by 31 % with the inclusion of 7.5 wt% ACFs. This composite performance by incorporating ACFs is encouraging despite the lower surface roughness and surface energy of ACFs (due to the absence of surface functionalization and sizing) as well as their lower tensile strength and modulus properties as compared to commercial surface-functionalized and sized carbon fibers.

Cell migration is a crucial parameter for disease progression in cancer. Reactive oxygen species (ROS) levels are involved in the regulation of the migration process, however, the exact role of free radical generation and where it occurs is unknown. Here we use a diamond-based quantum sensing technique to detect free radicals during cancer cell migration in real time with subcellular resolution. We investigated metastatic MDA-MB-231 human breast cancer cells and observed free radical formation after 16 h of starvation and 24 h of migration under low-serum conditions. Intracellular diamond dynamics were monitored at different migration points (0, 12, and 24 h), and cell morphology was evaluated. Additionally, the number of focal adhesions was analyzed as an indicator of the migratory potential of the cells. We further measured free radical generation under nicotinamide adenine dinucleotide phosphate hydrogen NADPH oxidases 2 (NOX2) inhibition by apocynin. We found that free radical levels decreased after 24 h treatment with 36 μg/mL apocynin while the levels of ROS and the migratory capacity of the cells increased. Our results evidence the complexity of the redox regulation in migrating cancer cells and offer a novel approach to specifically and locally interrogate pivotal players of the oxidative network behind metastatic success.