Materials Science and Engineering: R: Reports最新文献

Fire safety and prevention of combustible materials are of paramount importance in modern society but have been a global challenge. Frequent fire disasters cause massive casualties and irreparable property losses and negatively impact the global environment. A recent increasing concern is to develop smart fire warning materials and sensors that combine traditional passive flame retardant strategies and active fire alarm response. However, there still lacks an incisive and comparative overview of such fire warning systems. This review comprehensively discusses passive flame retardant materials, traditional active fire warning sensors, and next-generation smart fire warning materials and sensors, in addition to the flammability of combustible materials. The conceptual design, synthesis, characterizations, and fabrication strategies of smart warning materials are systematically reviewed. Subsequently, the performance and applications of different fire warning sensor systems, including resistance-type, phase/shape change, thermoelectric responsive and colour-change observation, were reviewed and compared to understand their features and working mechanisms better. Finally, some key challenges associated with fire warning materials/sensors are highlighted, following which future perspectives and opportunities are proposed.

Carbons with hierarchical pores in the range of few nanometers obtained via template-assisted methods offer a great control over structure and geometry of pores, keeping them uniformly distributed and better connected. Another advantage is the easy functionalization of templated porous carbons (TPCs) by various dopants, which makes them excellent materials for catalysis, energy storage and conversion, sensors and environmental applications. Herein, beyond zeolite-templated carbons, key methodologies based on the template material such as organic and metal oxides, silica, polymers, metal-organic framework (MOFs) and bio-originated materials used for the preparation of porous carbons possessing predetermined structure and composition, have been reviewed. The effects of precursor material on the textural and structural properties of TPCs have been described. In scope of applying novel methods such as evaporation induced self-assembling (EISA), the influence of different templates on the properties of resulting materials has been discussed. Further, advances on the template-induced synthesis of self-supporting metal-organic frameworks and their utilization as advanced templates have been described. Moreover, self-templates are especially emphasized, application of which in our opinion can provide a sustainable large-scale production of TPCs. The recent progress in the study of the diffusional processes, energy and biomedical applications as well as the confinement effects of different liquids and proteins within the porous matrices of template-derived carbons, have been reviewed.

Amorphization of crystalline structures is a ubiquitous phenomenon in metals, ceramics, and intermetallic compounds. Although the amorphous phase generally has a higher Gibbs free energy than its crystalline counterpart, there are many methods by which amorphization can be generated. The requirement to create an amorphous phase from a solid crystalline one is to increase its free energy above a critical level which enables this transition. In this review, our focus is on amorphization induced by mechanical deformation which can be imparted by a variety of means, prominent among which are tribological processes, severe plastic deformation, nanoindentation, shock compression, diamond anvil cell and ball milling/mechanical alloying. The deformation introduces defects into the structure, raising its free energy to the level that it exceeds the one of the amorphous phase, thus propitiating conditions for amorphization. Experimental observations of amorphization in metallic alloys, intermetallic compounds, ionically and covalently bonded materials are presented and discussed. There is also an observation of amorphization in a biological material: it is generated by impact deformation of hydroxyapatite in the mantis shrimp club. We also focus on the fundamental mechanisms of plastic deformation of amorphous materials; this is a closely linked process by which deformation continues, beyond amorphization, in the new phase. Observations and analyses of amorphization are complemented by computational simulations that predict the process of mechanically-induced amorphization and address the mechanisms of this transformation.

Wearable biochemical sensors have received substantial attention in recent years due to their great potential to provide insights into the physical condition of individuals. Based on the innovative biochemical sensing mechanisms and the recent advances in material science, the integrated biosensors are moving toward soft and small on-body electronic systems that can smartly and persistently monitor tiny changes in biochemical markers. They are beginning to transform almost every aspect of healthcare. This review looks into the state-of-the-art advances in this rising field by connecting the noninvasive biochemical sensing principles, materials science, advanced integration methods and the most representative cases of health monitoring wearable biosensors. Specifically, starting with a brief overview of the trends in wearable healthcare devices, we introduce the fundamental of chemistry for bio-sensing. The subsequent content highlights the contributions of nanomaterials and nanotechnologies in integrating and achieving on-body bio-sensing systems. We also discuss the key issues emerging in this area from a biocompatibility and material perspective. In the end, the review concludes with a summary of opportunities where advances in biochemistry and nanotechnology will be significant for future progress.

Aqueous batteries (ABs) have been regarded promising candidates for large-scale energy-storage applications due to their low-cost, high-safety, ease-of-fabrication, and high ionic conductivity. In contrast to standard rigid battery devices, flexible batteries can retain their functionality under deformation such as bending, twisting, rolling, or stretching. Therefore, the flexible solid-state ABs (FSABs) accelerates their practical application in wearable electronics. To date, numerous studies have focused on the optimization of the electrolyte, the electrode design, and the battery preparation processes to enhance both electrochemical performance and mechanical robustness. Although some reviews mention FSABs in a wider context, no exclusive review on FSABs for wearable electronics exists. Such a review is presented here, containing all aspects of the engineering, design and characterization of FSABs. The review presented gives an ample introduction to the basic principles of the energy storage mechanisms, the evaluation of the flexibility, and the design principles of FSABs. Furthermore, the recent progress in the electrochemical performance and mechanical flexibility of FSABs and their for practical applications in wearable electronic devices are comprehensively summarized. Finally, our insights regarding major challenges and prospective solutions in future research are provided to guide the further development of this fascinating and fast-evolving research area of FSABs.

Nature has created high-performance materials and structures over millions of years of evolution. Inspired by the concepts and design principles evident in natural materials and structures, high-performance tactile sensors, based on bioinspired structures/functions, natural biopolymers, and biomimetic strategies, have been developed. However, the primary challenge is to develop novel sensing mechanisms and device structures that are sufficiently sensitive and stretchable using bioinspired materials. Herein, we review the recent advancements made in this field, focusing on biomimetic approaches to produce tactile sensors with essential sensing capabilities and the development of bioinspired materials with the desired electrical and mechanical properties. In addition, we highlight the potential applications of these devices and discuss the potential directions for future work.

The combination of multiple-principal element materials, known as high-entropy materials (HEMs), expands the multi-dimensional compositional space to gigantic stoichiometry. It is impossible to afford a holistic approach to explore each possibility. With the advance of the materials genome initiative and characterization technology, a high-throughput (HT) approach is more reasonable, especially to identify the specified functions for the new HEMs development. There are three major components for the HT approach, which are the computational tools, experimental tools, and digital data. This article reviews both the materials informatics and experimental approaches for the HT methods. Applications of these tools on composition-varying samples can be used to obtain stoichiometry effectively and phase-structure-property relationships efficiently for the materials-property database establishment. They can also be used in conjunction with machine learning (ML) to improve the predictability of models. These ML tools will be an essential part of HT approaches to develop the new HEMs. The ML-developed HEMs together with ML-created other materials are positioned in this manuscript for future HEMs advancement. Comparing all the reviewed properties, the hierarchical microstructures together with the heterogeneous grain sizes show the highest potential to apply ML for new HEMs, which needs HT validations to accelerate the development. The promising potential and the database from the HEMs exploration would shed light on the future of humanity building from the scratch of Mars regolith.

The desire for developing ultraviolet optoelectronic devices has prompted extensive studies toward wide-bandgap semiconductor ZnO and its related alloys. Bandgap engineering as well as p-type doping is the key toward practical applications of ZnO. As yet, stable and reproducible p-type doping of ZnO remains a formidable challenge. To circumvent p-type conductivity, ZnO-based optoelectronic devices have been developed with hetero-structures of ZnO alloys. In past decades, substantial efforts have been made to engineer the band structure of ZnO via isovalent cation- or anion-substitution for obtaining desired material properties, and considerable progresses have been achieved. The purpose of this review is to summarize recent advances in the experimental and theoretical studies on bandgap engineering of ZnO by formation of multi-component alloys, and the development of related hetero-structures and optoelectronic devices. First, we briefly introduce the general properties, epitaxial growth techniques, and bandgap engineering of ZnO. Then, we focus on presenting the current status of researches on ZnO ternary and quaternary alloys for bandgap engineering. The issues about substituent solubility limit and phase separation, as well as variations of lattice parameters and bandgap with the substituent content in the alloys are discussed in detail. Further, ZnO alloys based hetero-structures including hetero-junctions, quantum wells, and superlattices are reviewed, and recent achievements in the area of optoelectronic devices based on ZnO multi-component alloys are summarized. The review closes with outlooking the likely developing trend of multi-component alloys for the bandgap engineering of ZnO and related hetero-structures, and the potential and pathway of multi-component alloys in settling the p-type doping of ZnO.

The technology to record image information at high resolution is of great importance in the optical areas of applied physics and biochemical imaging, as well as in commercial imaging applications such as cameras and machine vision. Organic semiconductors are drawing interest as photodetecting materials for next-generation high-resolution image sensors (IS) owing to their excellent properties such as high absorption coefficient, and color tunability and cost-effective manufacturability. These advantages offer the potential to exceed the technical limitation of silicon-based IS. This article reviews the state-of-the-art technologies of materials and devices in solution-processed organic photodiodes (OPDs) to meet the demands for future high-resolution ISs, which involves challenges ranging from the absence of a fundamental understanding of OPDs to commercialization requirements. Further, this article overviews the progress in the industry as well as academic society. The various requirements and technologies for the development of color-filter-free OPDs with narrow-wavelength detection are also discussed. This review concludes with an outlook of advances in these materials and devices to open up new commercialization routes.

In recent years, the development of personal protective equipment (PPE) for health care workers (HCWs) attracted enormous attention, especially during the pandemic of COVID-19. The semi-permeable protective clothing and the prolonged working hours make the thermal comfort a critical issue for HCWs. Although there are many commercially available personal cooling products for PPE systems, they are either heavy in weight or have limited durability. Besides, most of the existing solutions cannot relieve the perspiration efficiently within the insolation gowns. To avoid heat strain and ensure a longtime thermal comfort, new strategies that provide efficient personal thermal and moisture management without compromising health protection are required. This paper reviews the emerging materials for protective gown layers and advanced technologies for personal thermal and moisture management of PPE systems. These materials and strategies are examined in detail with respect to their fundamental working principles, thermal and mechanical properties, fabrication methods as well as advantages and limitations in their prospective applications, aiming at stimulating creative thinking and multidisciplinary collaboration to improve the thermal comfort of PPEs.