Materials Today Advances最新文献

Electrochemically powered carbon nanotube (CNT) yarn muscles are of increasing interest because of their advantageous features as artificial muscles. They are light, and have high electrical properties, mechanical strength, and chemical stability. Twist-based CNT yarn muscles show superior actuation performance: 30 times the work capacity and 85 times the power density of natural muscles. Despite achieving these high performances, there is still potential for performance improvement because their twisted structure is not fully utilized. In particular, designing a cross-sectional structure that allows ions to freely enter and exit the twisted structure of the yarn muscle is necessary. Here, we propose highly enhanced artificial muscles with high chemical stability that consist of only nanocarbon materials of carbon nanoscroll (CNS) and twisted CNT yarns. The CNS/CNT yarn muscles (CCYM) can improve the ion accessibility and utilization of the twist structure. The maximum contractile stroke, work capacity, power density, and energy conversion efficiency of the CCYM were 20.11%, 2.26 J g⁻¹, 0.53 W g⁻¹, and 3.39%, which are 1.4-, 1.4-, 4.8, and 4.3 times that of the pristine CNT yarn muscles, respectively. The effects of CNS on CCYM were confirmed by experimental and theoretical analyses. Additionally, in a solid electrolyte, which opens up new application possibilities, the CCYM demonstrates high actuation performance (16.38%) with very low input energy.

TRistructural ISOtropic (TRISO) fuel is a leading-edge nuclear fuel form representing a departure from the more traditional nuclear fuel forms utilized in the reactor fleet of today. Rather than a monolithic fuel pellet of uranium dioxide, integral fuel forms containing TRISO fuel are composed of thousands of microencapsulated uranium-bearing fuel kernels and individually coated with multiple layers of pyrolytic carbon and silicon carbide. These multilayered ceramic coatings serve as an environmental barrier to ensure radioactive and chemically reactive fission products are contained within the reactor fuel elements, but also participate in the transfer of heat generated in the nuclear fuel to the coolant – the primary purpose of a nuclear reactor. Since traditional thermal property measurement techniques, such as laser flash analysis, would be unable to resolve the thermal properties of the individual TRISO coating layers, a simplified frequency-domain thermoreflectance technique has been developed to rapidly map the thermal properties of TRISO particles. Using this technique, the thermal properties of TRISO particles have been mapped from room temperature up to 1000 °C to examine the spatial variation and temperature-dependency of the thermal properties within each layer. Additionally, spatial-domain thermoreflectance was used to examine the anisotropy of the thermal properties for each layer at different locations within a single TRISO particle, and across multiple TRISO particles to assess the intra- and inter-particle uniformity of thermal properties, respectively. To elucidate the underlying causes for the measured variations in thermal properties, scanning electron microscopy and Raman spectroscopy were used to examine variations in microstructure and chemical bonding within the different coating layers. Results from this work are then compared with previous examinations of TRISO fuel particles and microstructurally driven mechanisms for the variations in the measured thermal properties of the different carbonaceous layers are discussed.

Compared with the wound in the flat part of human body, the repair of the wound in the joint, armpit and other frequently moving parts is still a complex problem. Although many flexible and adhesive hydrogel dressings for the repair of wounds at moving parts have been developed, in order to improve their flexibility and adhesion, most hydrogel dressings use synthetic polymers and natural polymers to form composite hydrogels, which greatly reduces their biocompatibility and bioactivity compared with a single natural polymer hydrogel. They can only passively provide a barrier to the wound and the process of wound repair is slow, which seriously hinders their further application. Inspired by commercial adhesive bandages, we have successfully constructed a flexible adhesive hydrogel dressing of embedded structure with pro-angiogenesis activity. The hydrogel was prepared by the adhesive and non-adhesive parts by topological adhesion and molecular entanglement. Due to the high-density hydrogen bonding, hydrogels possessed good adhesion and flexibility, which allowed them to repair wounds of moving parts successfully. In addition, the non-adhesive part loaded with exosomes was directly in contact with the wound, minimizing the stimulation of the wound tissue by cytotoxic materials, and continuously releasing active substances to promote vascular regeneration. This biocompatible flexible and adhesive hydrogel dressing with pro-angiogenesis activity shows strong potential in wound tissue remodeling, providing a new strategy for the treatment of moving parts or sensitive wound parts.

Two-dimensional (2D) metallic transition metal dichalcogenides (TMDs) have garnered significant attention as promising candidates for various applications, including electronics, spintronics, and energy-related fields. Their appeal lies in their exceptional electronic conductivity, room-temperature ferromagnetism, charge density wave (CDW) phenomena, and catalytic properties, among other attributes. Among the diverse array of metallic TMDs, vanadium dichalcogenides (VX₂, X = S, Se, and Te) stand out due to their distinctive set of physical and chemical properties. These properties have positioned VX₂ materials at the forefront of both fundamental research and technological exploration in fields such as condensed matter physics, materials science, and device physics. In this comprehensive review, we present a thorough investigation of the recent advancements in 2D metallic VX₂ materials and related heterostructures in the aspects of their structures, fabrication methods, key properties, and potential applications. First, the electronic and crystal structures of 2D VX₂ are introduced. Second, the growth methods of VX₂ and their heterostructures are discussed. Then, the novel physical properties and potential applications of 2D VX₂ and its heterostructures are highlighted. Finally, we assess the current state of development in this growing field, acknowledging the obstacles ahead and the promising avenues for future research.

Perovskite solar cells (PSCs) are believed to be optimistic for commercial deployment soon since the power conversion efficiency of PSCs presently reaches up to 26.10 % due to the intensive efforts these years. The two-step method is comparatively more suitable for scalable perovskite films, where lead halides and ammonium salts are prepared in separate precursors and deposited sequentially. Therefore, the reactivity between these two precursors governs the quality of final perovskite films and the intrinsic non-radiative recombination (NRR) at the perovskite's interfaces. Herein, we empowered both types of precursors, one by one and then simultaneously, with triethylsilane (TES) to investigate its effect on the (FAPbI₃)_1-x (MAPbBr₃)_x perovskite's morphological and optoelectronic properties. TES, with ethyl moieties and metalloid center, in ammonium salts delivers homogeneous perovskites' crystals and inhibits the NRR of perovskite films by reducing the defects and trap states. As a result, the optimized devices exhibit not only improved device performance (particularly for the increased fill factors and open circuit voltages) but also enhanced stabilities.

The crystal structures and optical properties of full-series multilayered GaTe_1−xS_x (0 ≤ x ≤ 1) are examined. The results reveal that the monoclinic (M) phase dominates for 0 ≤ x ≤ 0.4, and the hexagonal (H) phase dominates for 0.425 ≤ x ≤ 1. The full-series multilayer GaTe_1−xS_x exhibited strong photoluminescence. The emission range of M-GaTe_1−xS_x (0 ≤ x ≤ 0.4) layers displays 1.65–1.77 eV (700–750 nm) and that of the H-GaTe_1−xS_x (0 ≤ x ≤ 1) layers is 1.588–2.5 eV (496–780 nm). Micro-time-resolved photoluminescence (μTRPL) revealed that the M-phase had a shorter PL recombination lifetime than H-phase because the surface effect. The multilayer GaTe_1−xS_x (0 ≤ x ≤ 1) exhibited superior light emission and absorption capabilities for application in light-emitting and photocatalytic devices. The GaTe_0.5S_0.5 nanosheet photocatalyst demonstrated the best photocatalytic performance because its abundant surface state and mixed phases to enhance the photo-degradation ability.

Zeolitic Imidazolate Framework-67 (ZIF-67) has been used in a variety of applications including catalysis, separations, and energy storage. However, the weak hydrostability of ZIF-67, due to structural hydrolysis and degradation, dramatically limits their applicability after aqueous exposure. In this work, cosolvent-stabilized superhydrophobic, highly hydrostable ZIF-67 was synthesized at room temperature using a facile, one-pot hydrothermal synthesis route, and the effect of cosolvent concentration on ZIF-67 crystal structure properties and hydrostability was studied systematically. The underlying mechanism for the cosolvent-supported hydrostability improvement was also proposed. Furthermore, the influence of hydrotreatment on the resultant ZIF-67s' catalytic performance was studied in the ‘Sabatier reaction’ for CO₂ to synthetic natural gas (CH₄) conversion. The ZIF-67-derived calcined catalysts obtained from the hydrotreated samples of the cosolvent-stabilized ZIF-67 exhibited no prominent loss in catalytic performance and showed better CO₂ conversion, higher CH₄ selectivity, and less CO production, in comparison to the conventional ZIF-67 samples. Notably, the use of a lower ligand-to-metal ratio (∼8) in the current synthesis significantly reduced the overall chemical consumption, achieving highly economically and environmentally friendly manufacturing of exceptionally hydrostable ZIF-67.

With the development of minimally invasive approaches, calcium-based injectable bone paste has attracted attention as a synthetic alternative due to its biodegradability and analogous composition with native bone. However, this approach is associated with the problem of the materials being absorbed before new bone formation has occurred, with a high resorption, and degradation rate. Here, a poly(lactic-co-glycolic acid) (PLGA)/magnesium hydroxide (MH)/vitamin D (Vit D) microsphere-incorporated α-calcium sulfate hemihydrate (α-CSH)/beta-tricalcium phosphate (β-TCP) injectable paste was designed for the regeneration of bone tissue. The combination of the bioceramic particles with α-CSH demonstrated an appropriate setting time for ease of use in clinical practice and enhanced mechanical properties. Additionally, the introduction of a bone paste with the MH and Vit D-incorporated PLGA microsphere induced osteogenic differentiation and alleviated the inflammatory response, which may occur after massive bone surgery. Based on these findings, this paper presents a versatile bone paste that promotes osteogenesis and modulates the osteoimmune microenvironment for effective bone regeneration.

The martensitic microstructure decides on the functional properties of shape memory alloys. However, for the most commonly used alloy, NiTi, it is still unclear how its microstructure is built up because the analysis is hampered by grain boundaries of polycrystalline samples. Here, we eliminate grain boundaries by using epitaxially grown films in (111)_B2 orientation. By combining scale-bridging microscopy with integral inverse pole figures, we solve the puzzle of the hierarchical martensitic microstructure. We identify two martensite clusters as building blocks and three kinds of twin boundaries. Nesting them at different length scales explains why habit plane variants with ${⟨011⟩}_{\mathrm{B}{19}^{\text{'}}}$ twin boundaries and {942} habit planes are dominant; but also some incompatible interfaces occur. Though the observed hierarchical microstructure agrees with the phenomenological theory of martensite, the transformation path decides which microstructure forms. The combination of local and global measurements with theory allows solving the scale bridging 3D puzzle of the martensitic microstructure in NiTi exemplarily for epitaxial films.