Frontiers of Materials Science最新文献

As a structural and functional material with excellent properties, ceramics play an extremely important role in a wide range of industries, including life and production. To expand the range of applications for ceramic materials, ceramics are often joined to metals and then used. Among the physical and chemical joining methods of ceramics to metals, the AMB method is efficient and simple, suitable for industrial applications, and has been a hot topic of research. However, due to the problems of residual stresses caused by the large difference in thermal expansion coefficients between ceramic and metal brazing, composite fillers have become a very worthwhile solution by regulating the physical properties of the brazing material and improving the weld structure. This review describes the wetting principle and application of Ag-Cu-Ti active metal filler in the field of ceramic joining, with emphasis on the current stage of composite filler, and discusses the influence on the former brazing properties and organization after the introduction of dissimilar materials.

It is still a challenge to prepare a water- and polymer-based electrospun air filter film with high efficiency filtration, low pressure drop, and good mechanical properties. To address this issue, polyvinyl alcohol (PVA) was employed as the main material, mixing polyethyleneimine (PEI), bamboo-based activated carbon (BAC) and cellulose nanocrystal (CNC) to construct the air filter film by electrostatic electrospinning. In this system, the negatively charged BAC and CNC are fixed in the system through bonding with the positively charged PEI, showing a double adsorption effect. One is the mechanical filtration of the porous network structure constructed by PVA@PEI electrospun nanofibers, and the other is the electrostatic adsorption of PM2.5 on the surface of BAC and CNC. It is significant that the resulting composite air filter displays a high filtration efficiency of 95.86%, a pressure drop of only 59 Pa, and good thermal stability. Moreover, the introduced methyltrimethoxysilane (MTMS) endows it with good water-resistance. Given these excellent performances, this system can provide theoretical and technical references for the development of water- and polymer-based electrospun air filter film.

Among various metal chalcogenides, metal oxides and phases of copper sulfide, copper(II) sulfide (covellite, CuS) nanostructures have enjoyed special attentiveness from researchers and scientists across the world owing to their complicated structure, peculiar composition and valency, attractive and panoramic morphologies, optical and electrical conductivity, less toxicity, and biocompatibility that can be exploited in advanced and technological applications. This review paper presents a brief idea about crystal structure, composition, and various chemical methods. The mechanism and effect of reaction parameters on the evolution of versatile and attractive morphologies have been described. Physical properties of CuS and its hybrid nanostructures, such as morphology and optical, mechanical, electrical, thermal, and thermoelectrical properties, have been carefully reviewed. A concise account of CuS and its hybrid nanostructures’ diverse applications in emerging and recent applications such as energy storage devices (lithium-ion batteries, supercapacitance), sensors, field emission, photovoltaic cells, organic pollutant removal, electromagnetic wave absorption, and emerging biomedical field (drug delivery, photothermal ablation, deoxyribonucleic acid detection, anti-microbial and theranostic) has also been elucidated. Finally, the prospects, scope, and challenges of CuS nanostructures have been discussed precisely.

Malignant neoplasms represent a significant global health threat. To address the need for accurate diagnosis and effective treatment, research is underway to develop therapeutic nanoplatforms. Iron oxide nanoparticles (NPs), specifically Fe₃O₄ NPs have been extensively studied as potential therapeutic agents for cancer due to their unique properties including magnetic targeting, favorable biocompatibility, high magnetic response sensitivity, prolonged in vivo circulation time, stable performance, and high self-metabolism. Their ability to be integrated with magnetic hyperthermia, photodynamic therapy, and photothermal therapy has resulted in the widespread use of Fe₃O₄ NPs in cancer diagnosis and treatment, making them a popular choice for such applications. Various methods can be employed to synthesize magnetic Fe₃O₄ NPs, which can then be surface-modified with biocompatible materials or active targeting molecules. Multifunctional systems can be created by combining Fe₃O₄ NPs with polymers. By combining various therapeutic approaches, more effective biomedical materials can be developed. This paper discusses the synthesis of Fe₃O₄ NPs and the latest research advances in Fe₃O₄-based nanotherapeutic platforms, as well as their applications in the biomedical field.

Few-layers WS₂ was obtained through unique chemical liquid exfoliation of commercial WS₂. Results showed that after the exfoliation process, the thickness of WS₂ reduced significantly. Moreover, the NiFe₂O₄ nanosheets/WS₂ composite was successfully synthesized through a facile hydrothermal method at 180 °C, and then proven by the analyses of field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The composite showed a high specific surface area of 86.89 m²·g⁻¹ with an average pore size of 3.13 nm. Besides, in the three-electrode electrochemical test, this composite exhibited a high specific capacitance of 878.04 F·g⁻¹ at a current density of 1 A·g⁻¹, while in the two-electrode system, the energy density of the composite could reach 25.47 Wh·kg⁻¹ at the power density of 70 W·kg⁻¹ and maintained 13.42 Wh·kg⁻¹ at the higher power density of 7000 W·kg⁻¹. All the excellent electrochemical performances demonstrate that the NiFe₂O₄ nanosheets/WS₂ composite is an excellent candidate for supercapacitor applications.

Autonomous self-healing hydrogels were achieved through a dynamic combination of hydrogen bonding and ferric ion (Fe³⁺) migration. N,N′-methylenebis (acrylamide) (MBA), a cross-linking agent, was added in this study. Poly(acrylic acid) (PAA)/Fe³⁺ and PAA–MBA/Fe³⁺ hydrogels were prepared by introducing Fe³⁺ into the PAA hydrogel network. The ionic bonds were formed between Fe³⁺ ions and carboxyl groups. The microstructure, mechanical properties, and composition of hydrogels were characterized by field emission scanning electron microscopy and Fourier transform infrared spectroscopy. The experimental results showed that PAA/Fe³⁺ and PAA–MBA/Fe³⁺ hydrogels healed themselves without external stimuli. The PAA/Fe³⁺ hydrogel exhibited good mechanical properties, i.e., the tensile strength of 50 kPa, the breaking elongation of 750%, and the self-healing efficiency of 82%. Meanwhile, the PAA–MBA/Fe³⁺ hydrogel had a tensile strength of 120 kPa. These fabricated hydrogels are biocompatible, which may have promising applications in cartilage tissue engineering.

The layer-structured composites were built by the dielectric and insulating layers composed of polyvinylidene fluoride (PVDF) and low-density polyethylene (LDPE) composites containing barium titanate (BT) to modulate the dielectric and energy storage properties of the composites. The simulations on the interface models for molecular dynamics and the geometric models for finite element analysis were performed together with the experimental characterization of the morphology, dielectric, and energy storage properties of the composites. The results revealed that polyethylene as an insulating layer played a successful role in modulating dielectric permittivity and breakdown strength while BT particles exerted positive effects in improving the miscibility between the composed layers and redistributing the electric field. The strong interface binding energy and the similar dielectric permittivity between the PVDF layer and the BT20/LDPE layer made for the layer-structured composites with a characteristic breakdown strength (E_b) of 188.9 kV·mm⁻¹, a discharge energy density (U_d) of 1.42 J·cm⁻³, and a dielectric loss factor (tanδ) of 0.017, which were increased by 94%, 141%, and decreased by 54% in comparison with those of the BT20/PVDF composite, respectively.

Nitrogen-doped carbon-coated hollow SnS₂/NiS (SnS₂/NiS@N-C) microflowers were obtained using NiSn(OH)₆ nanospheres as the template via a solvent-thermal method followed by the polydopamine coating and carbonization process. When served as an anode material for lithium-ion batteries, such hollow SnS₂/NiS@N-C microflowers exhibited a capacity of 403.5 mAh·g⁻¹ at 2.0 A·g⁻¹ over 200 cycles and good rate performance. The electrochemical reaction kinetics of this anode was analyzed, and the morphologies and structures of anode materials after the cycling test were characterized. The high stability and good rate performance were mainly due to bimetallic synergy, hollow micro/nanostructure, and nitrogen-doped carbon layers. The revealed excellent electrochemical energy storage properties of hollow SnS₂/NiS@N-C microflowers in this study highlight their potential as the anode material.

Carbon aerogels derived from biomass have low specific capacity due to the underutilized structure, limiting their application in high-performance supercapacitors. In this work, the hierarchical nickel sulfide/carbon aerogels from liquefied wood (LWCA-NiS) were synthesized via a simple two-step hydrothermal method. Benefitting from the unique 3D coral-like network structure of LWCA, self-assembled NiS nanowires with the dandelion-like structure showed high specific surface (389.1 m²·g⁻¹) and hierarchical pore structure, which increased affluent exposure of numerous active sites and structural stability, causing superior energy storage performance. As expected, LWCA-NiS displayed high specific capacity (131.5 mAh·g⁻¹ at 1 A·g⁻¹), good rate performance, and highly reversible and excellent cycle stability (13.1% capacity fading after 5000 cycles) in the electrochemical test. Furthermore, a symmetrical supercapacitor using LWCA-NiS-10 as the electrode material delivered an energy density of 12.7 Wh·kg⁻¹ at 299.85 W·kg⁻¹. Therefore, the synthesized LWCA-NiS composite was an economical and sustainable candidate for the electrodes of high-performance supercapacitors.

Polyurethane (PU) foams are widely used in thermal management materials due to their good flexibility. However, their low thermal conductivity limits the efficiency. To address this issue, we developed a new method to produce tannic acid (TA)-modified graphene nanosheets (GTs)-encapsulated PU (PU@GT) foams using the soft template microstructure and a facile layer-by-layer (L-B-L) assembly method. The resulting PU@GT scaffolds have ordered and tightly stacked GTs layers that act as three-dimensional (3D) highly interconnected thermal networks. These networks are further infiltrated with polydimethylsiloxane (PDMS). The through-plane thermal conductivity of the polymer composite reaches 1.58 W·m⁻¹·K⁻¹ at a low filler loading of 7.9 wt.%, which is 1115% higher than that of the polymer matrix. Moreover, the mechanical property of the composite is ∼2 times higher than that of the polymer matrix while preserving good flexibility of the polymer matrix owing to the retention of the PU foam template and the construction of a stable 3D graphene network. This work presents a facile and scalable production approach to fabricate lightweight PU@GT/PDMS polymer composites with excellent thermal and mechanical performance, which implies a promising future in thermal management systems of electronic devices.