Materials Science and Engineering: R: Reports最新文献

Cellulosic fibers have garnered significant attention in both academic research and industry due to their appealing physicochemical properties, distinctive structural qualities, and wide-ranging applications. In the realm of wood adhesives, the utilization of cellulose has witnessed a substantial surge in the last decade. Cellulose is employed either as reinforcement in the manufacturing of various wood adhesives or as a binder for wood bonding, offering a sustainable and eco-friendly alternative to traditional adhesives. This surge in the utilization of cellulose-based wood adhesives has led to remarkable improvements in both mechanical and physical properties, contributing to enhanced wood composite materials. This review aims to provide insight into recent developments in the rapidly expanding field of cellulose-based wood adhesives, encompassing fundamental research to practical applications. The initial section offers an updated depiction of cellulose, encompassing its chemical structure, characteristics, classification, and chemical modifications, highlighting its versatility and suitability in adhesion science. The paper culminates with a comprehensive overview of its benchmarking, addressing economic and environmental aspects, and outlining prospects and future directions for sustainable wood adhesive technology. In summary, cellulose derivatives have become pivotal in enhancing wood adhesive properties while aligning with sustainability goals, making this review a valuable resource to navigate the evolving landscape of cellulose-based wood adhesives.

Over 40 % of global energy consumption is attributed to thermal regulation in buildings, highlighting the imperative for low-carbon structures. Aerogel insulation materials with low thermal conductivity show promise for energy-saving buildings. However, their widespread adoption is hindered by inadequate mechanical robustness, stability, and fire resistance. Herein, inspired by plant root-soil structures, mechanically robust Poly-p-phenylene benzoxazole (PBO) nanofiber-reinforced silica aerogels (BNFSi) are designed and synthesized via a dimension-upgrading strategy. The optimized BNFSi are characterized by Compressive strength (3.2 MPa). Additionally, the aerogel demonstrates several outstanding properties, such as low thermal conductivity (27.3 mW m⁻¹ K⁻¹), superior flame retardancy, high mass retention rate (79.7 %), high reflectivity in the visible to near-infrared spectrum (∼ 92 %), and inherent super-hydrophobic surface with a 150.3° water contact angle, indicating self-cleaning potential. The biomimetic-designed structure resolved the inherent brittleness of the silica network while inducing fire-resistant and ideal insulating performance, thus offering a promising avenue for advancing energy-conserving buildings, aligning with the objectives of next-generation eco-conscious construction.

Due to the high prevalence of cancer in modern societies, it is crucial to monitor and scrutinize chemotherapeutic medications closely and precisely. Administering antineoplastic drugs to suppress the growth or destroy cancer cells is one of the most effective treatments, which is widely practiced at present. These anticancer drugs are designed to target cancer cells, whereas in a few cases, they could also become toxic to non-cancerous cells, posing risks not only to patients but also to healthcare workers and the soil and aquatic environments. Therefore, the concentrations of these drugs need to be quantified precisely at their nano/picomolar levels to attain better efficacy of the intended treatment, safeguard the patients from adverse effects, and protect the environment. Among various methodologies, electrochemical techniques are highly appreciated owing to their high sensitivity and selectivity, low cost, ease of operation, rapid response, low sample requirement, and ease of miniaturization. Even though hundreds of sensors have been reported for the electrochemical detection of these antineoplastic drugs, only a few reviews highlighted their prominence. While certain aspects of the electrochemistry of antineoplastic drugs can be found in those reviews, many important aspects are still inadequately addressed and remain significantly behind the current state of the art. Thus, we intend to bridge this gap by systematically reviewing the electrochemical sensors developed for the selective detection of various antineoplastic drugs. Significant emphasis has been given to the electrode materials, fabrication procedures, and sensing strategies, as well as a comparison of their analytical performances and evaluation of their advantages and limitations. This review would pave a new path for developing wearable, continuous monitoring point-of-care systems for the on-site and online sensing of multiple chemotherapeutic drugs, ensuring the livability of cancer patients by attaining maximum drug efficacy and minimizing or eradicating their adverse effects on humanity and the environment.

The emergence of the 5 G technology and universal smart electron devices urgently call for the exploration of highly efficient microwave absorption materials. MoS₂ is a potential dielectric microwave absorption material that offers the benefits of diverse morphologies/structures, adjustable bandgap, easy defects production, controllable electrical conductivity and high stability, but suffers from single dielectric loss capacity and impedance mismatching. Structural regulations and hybridization with foreign components have been extensively used to improve the microwave absorption performance of MoS₂. This review introduces the characteristics and microwave absorption mechanisms of MoS₂ nanomaterials for a comprehensive analysis, and systematically emphasizes the related key issues by summarizing progress of MoS₂-based microwave absorption materials. Three strategies are considered, namely (1) structural regulation of MoS₂ monocomponent via the control of morphology, heteroatom doping, defects and phases; (2) loss mechanism regulation of binary MoS₂-based composites via hybridization with other dielectric materials (e.g., carbon, MXene and polymer) or magnetic materials (e.g., ferrites and magnetic metals/alloys); (3) realization of multicomponent MoS₂-based composites with multidimensional hierarchical architectures using one-, two- and three-dimensional structures. Micro/nanostructure regulation, hybridization with foreign material and architectural design are discussed as the methods of controlling the loss mechanisms, impedance matching and microwave absorption performance of MoS₂-based composites. Finally, the ongoing challenges and future opportunities are prospected to surmount the current barriers and provide forward-looking guidance for the exploration of novel highly efficient MoS₂-based microwave absorption materials.

Threshold-type resistive switching (RS) is an essential electronic behavior in many types of integrated circuits and can be exploited in multiple applications, such as leaky integrate-and-fire neurons for artificial neural networks (ANNs). Many research articles have shown that metal/insulator/metal (MIM) devices using Ag electrodes exhibit stable threshold-type RS, but all of them presented large devices (>1 µm²) fabricated on unfunctional SiO₂/Si substrates. In this article, for the first time we integrate Ag-based threshold-type RS devices at the back-end-of-line interconnections of silicon microchips. The insulator used is multilayer hexagonal boron nitride (h-BN), and the size of the devices is ∼0.05 µm². The devices can switch between a high resistive state (HRS) and a low resistive state (LRS) without the need of any forming process, and we observe a high endurance over 1 million cycles over multiple devices. By performing circuit simulation using SPICE software, we confirm that this electrical behavior is suitable for being used as leaky integrate-and-fire electronic neuron in spiking neural networks for image recognition, and the h-BN artificial neurons operate correctly for 94 % of the images presented. Our study represents a significant advancement towards the integration of Ag-based threshold-type RS devices in silicon microchips.

The acquisition of multi-dimensional optical information such as intensity, wavelength and polarization provides new ideas for improving the performance of photodetector to meet the efficient recognition of targets in complex environments in the future. When light interacts with matter, the change in the polarization state of light will reflect the material composition, surface morphology, etc. It has important research value and application prospects in target recognition, remote sensing, quantum communication and biomedical. Traditional polarization-sensitive photodetection requires the combination of complex optical devices such as polarizers, wave-plates, and lenses to regulate the polarization and wave-front of light waves, resulting in complex detection systems, high power consumption, and low integration. Recently, the non-complementarity of extra-nuclear electron in transition-metal dichalcogenides leads to an increase in chemical bond complexity and a decrease in in-plane symmetric elements, making them sensitive to polarized light. It is expected to break away from the traditional design concept of complex polarization imaging systems and explore new polarization detection technologies. However, the polarization-sensitive photodetector is still of great challenge. In this study, we first explore the principles of polarized light generation and detection. Next, we analyze the novel polarization-sensitive materials by classifying them into three categories: geometrically anisotropic, intrinsically anisotropic, and heterostructure materials. On this basis, we outline the performance of polarization detector devices based on these three classes of materials and present some of the performance enhancement methods that have been summarized and discussed. Finally, we explore the prevailing challenges and prospects, offering insights into the potential trajectory of advancements within this burgeoning field.

Ongoing breakthroughs in the development of functional printing materials are leading to rapid and widespread industrialization of three-dimensional (3D) printing, accompanied by increasingly urgent requirements for methods to prevent problems such as tampering, counterfeiting and destruction of 3D printed products. Anti-counterfeiting of 2D printed products has a long history, but its methods are not suitable for application to 3D printed products, as the latter products have embedding that is substantially different to that of the former products. This review article analyses anti-counterfeiting techniques for 2D printed products, proposes two embedding strategies for 3D printing based on material-responsive properties and 3D digital information, and summarizes the progress and performance of the corresponding anti-counterfeiting methods. It is shown that among the embedded anti-counterfeiting methods that exploit the responsive properties of materials, methods based on optical properties, spectral properties and deformation properties of 3D printing materials are the focus of research on embedding anti-counterfeiting materials into 3D printed objects. In addition, it is demonstrated that state-of-the-art embedding-based anti-counterfeiting methods use 3D digital information interactions and depend on 3D digital watermarks, 3D identification codes and radio-frequency tagging. Finally, a detailed discussion is provided on the generation, integration, extension, detection and prediction of embedded security features that can be printed synchronously with a functional structure. This offers a unique perspective on standardization of embedding-based anti-counterfeiting methods used in 3D printing.

The limited activity and stability of conventional anodes in seawater have posed a significant obstacle to sustainable green hydrogen production directly from seawater via electrolysis. To address these challenges, we engineered Ti₃C₂Tx-MXene by incorporating iron and boron into its matrix (tagged FBT) for selective oxygen evolution reaction (OER). Positioning B underneath the top layer induces charge disparity on the Fe-sites, which influences the subsequent growth of the ZIF-67 metal-organic framework (MOF) on the MXene surface through Fe-O-Co ionic bonds. DFT calculations reveal a favorable binding energy of −2.30 eV at the heterointerface for ZIF-67 adsorption to the surface of FBT via O-Co bond, a shortened bond length of 1.94 Å, confirming the formation of ionic bonds. These ionic bonds tune the active sites for an enhanced and selective OER over chlorine evolution reaction (CER), preventing active Fe species' leaching and ensuring stability at >1.56 A cm⁻² in 6 M alkaline seawater over 370 hours. Further, FBT and ZIF-67/FBT require low overpotentials of 521.2 and 508 mV, respectively, to deliver 1 A cm⁻² in 6 M alkaline seawater. Our findings demonstrate a robust strategy to significantly expand the potential of MXenes from simple conductive substrates to efficient OER catalysts for seawater splitting and beyond.

High-entropy alloys (HEAs) stand out from multi-component alloys due to their attractive microstructures and mechanical properties. In this investigation, molecular dynamics (MD) simulation and machine learning (ML) were used to ascertain the deformation mechanism of AlCoCrCuFeNi HEAs under the influence of temperature, strain rate, and grain sizes. First, the MD simulation shows that the yield stress decreases significantly as the strain and temperature increase. In other cases, changes in strain rate and grain size have less effect on mechanical properties than changes in strain and temperature. The alloys exhibited superplastic behavior under all test conditions. The deformity mechanism discloses that strain and temperature are the main sources of beginning strain, and the shear bands move along the uniaxial tensile axis inside the workpiece. Furthermore, the fast phase shift of inclusion under mild strain indicates the relative instability of the inclusion phase of hexagonal close-packed (HCP). Ultimately, the dislocation evolution mechanism shows that the dislocations are transported to free surfaces under increased strain when they nucleate around the grain boundary. Surprisingly, the ML prediction results also confirm the same characteristics as those confirmed from the MD simulation. Hence, the combination of MD and ML reinforces the confidence in the findings of mechanical characteristics of HEA. Consequently, this combination fills the gaps between MD and ML, which can significantly save time, human power, and cost to conduct real experiments for testing HEA deformation in practice.

Evaporating metallic films on two-dimensional (2D) materials is a necessary process to build electronic devices, but it produces bond breaking and metal penetration in the 2D material, which degrades its properties and the figures-of-merit of the devices. Evaporating the metal in ultra-high vacuum (10⁻⁹ Torr) is a recognized method to reduce the damage, but the higher complexity and cost of the setup and its lower throughput makes developing other solutions highly desirable. All studies on ultra-high vacuum evaporation of metals on 2D materials evaluated the figures-of-merit of transistors fabricated following different protocols, with very scarce or without sub-nanometre information. Moreover, such studies employed 2D materials produced by chemical vapour deposition (CVD), which contain relatively large amounts of native defects, and hence, post-evaporation analyses do not allow identifying which defects are native and which ones are generated during metal evaporation. In this article we analyse the structure of defect-free mechanically exfoliated 2D materials via cross-sectional transmission electron microscopy (TEM) before and after Au evaporation (on top), and calculate the density of defects introduced. We find that evaporating the metal in a moderate vacuum atmosphere of 5 × 10⁻⁶ Torr is sufficient to avoid damage, leading to a nearly perfect van der Waals interface. By using density functional theory simulations we find that the presence of water molecules on the surface of the 2D material slightly distorts the position of the atoms in the crystalline hexagonal network, weakening the covalent bonds and reducing the energy for defect formation. We fabricate Au/h-BN/Au devices and observe that evaporating the Au at 5 × 10⁻⁶ Torr produces much less out-of-plane leakage current than evaporating at 3 × 10⁻⁵ Torr. The approaches here presented are easy to use and facilitate the introduction of 2D materials in electronic devices and circuits.