Porous silicon nitride (Si3N4) ceramics can be widely used in various fields, such as sound and shock absorption, filtration and so on, due to its high porosity and outstanding properties of ceramics. However, conventional preparation methods, such as gas-pressure/pressureless sintering, sintering reaction-bonded sintering and carbothermal reduction sintering, perform long sintering time, high energy consumption and high equipment requirements, which makes the preparation of porous Si3N4 ceramics expensive. Therefore, it is of great importance to explore a rapid and low-cost preparation method. In recent years, the direct preparation of porous Si3N4 ceramics by self-propagating high temperature synthesis (SHS) has showed great potential of which the heat released from the nitridation of Si powder could be used for the in-situ sintering of porous Si3N4 ceramics. In present paper, researches relating to the initiation of the SHS reaction, and microstructural evolution, mechanical properties, and reliability of the fabricated Si3N4 ceramics are summerized systematically. Porous Si3N4 ceramics with complete nitridation, excellent grain morphology and outstanding mechanical properties and reliability are obtained by adjusting raw materials and process parameters. Furthermore, the relationship between properties of grain boundary phase and high-temperature mechanical properties of SHS-fabricated porous Si3N4 ceramics is reviewed. Finally, the development direction of the self-propagating high temperature synthesis of porous Si3N4 ceramics is prospected.

Special ceramics are widely used in aerospace, electronics, information, new energy, machinery, chemical industry, and other emerging industries. Their high temperature preparation process is still dominated by traditional gas kilns and electric heating furnaces with high carbon emissions and high energy consumption. The energy conservation-emission reduction situation is grim at present. Therefore, China is facing great pressure to achieve ‘double carbon’ goal, badly needing research and promotion of clean and efficient heating technology. Microwave heating uses the dielectric loss of the material itself to absorb microwave and convert electromagnetic energy into heat energy at molecular level. In this way, heat is generated simultaneously both inside and outside the whole material, leading the temperature gradient very low in the whole material. In addition to the volumetric heating, selective heating, power redistribution, thermal upheaval, and microwave plasma effect are important characteristics of microwave sintering. Microwave heating has the advantages of energy conservation, environmental protection, improved product performance and reduced combustion carbon emissions. There are many reports on microwave synthesis of various oxides, carbides, nitrides ceramic powders, and microwave sintering ceramic composites domestic and abroad. In this paper, the basic theories of microwave sintering and microwave mixed sintering are reviewed firstly, and then the latest research progress on preparation of ceramic powders by microwave heating and ceramic materials preparation by microwave sintering is introduced. Finally, microwave heating used in sintering of ceramic engineering products is introduced, which shows the superiority of microwave sintering. The key problems and the future development direction of special ceramics prepared by microwave sintering are also proposed.

Silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites have become the preferred candidate for structural applications in advanced nuclear energy systems, because of their low neutron toxicity, neutron irradiation tolerance and high-temperature oxidation resistance. In recent years, both academia and industry either domestic or abroad have carried out a lot of researches on SiCf/SiC composites for nuclear application, and numerous important achievements have been made. This paper summarized and analysed some critical directions of SiCf/SiC composites for nuclear applications, including nuclear-grade SiC fibers, fibre/matrix interfaces, composite processing, modeling and simulation, corrosion behavior and surface protection, joining technology, as well as radiation damage. The key issues and potential solutions of SiCf/SiC composites for nuclear applications have been pointed out in account to the requirements, anticipating to be beneficial to promoting further researches and final applications.

Spontaneous coagulation casting (SCC) is a novel in-situ ceramic forming method, not only universal for various ceramics but also working well at room temperature in air. Here presents the finding of SCC, involving an anion dispersant which acts as both dispersing and coagulating agent. Then, the difference between SCC and other in-situ coagulation methods in principle was elucidated. In SCC, particles participate in the formation of organic network which originates from hydrophobic interaction and hydrogen bonding among the dispersant molecular chains. The ceramic gel formed by SCC is a physical gel and possesses low density which is conducive to water transportation and stress relaxation during drying. In contrast, the one by conventional gelcasting is a chemical gel in which particles are fixed by a dense organic network. Based on the hydrophobic interaction, this review focuses on the design and synthesis of a series of SCC agents to meet the demand of forming dense and porous ceramics from particles with different sizes. That is, an anion dispersant is hydrophobically modified by a surfactant with a short or long chain. The obtained two agents are used for preparation of dense and porous ceramics, respectively. Progress of key technologies in this area including ceramic joining without interface, construction of grain orientation, drying, preparation of dense ceramics and porous ceramics, by SCC is summarized. Typically, alumina disc with a diameter up to 1010 nm and alumina parts with complicated shape such as dome and guide are shown. Future development of SCC is also proposed to enable SCC is a more universal forming technology for advanced ceramics with a large and/or complicated dimension.

Oxygen reduction reaction (ORR) is the key reaction in cathode for fuel cells. Because of the sluggish kinetics, platinum (Pt) is widely used as the electrocatalysts for ORR. However, the high cost of Pt and poor stability of carbon black support under high voltage limit the commercialization and durability of fuel cells. Two-dimensional transition metal dichalcogenides (2D TMDs) possess large specific area, tunable electronic structure, and high chemical stability, making them a good candidate for ORR catalysts with high activity and durability. This paper reviews the recent progress of 2D TMDs-based ORR electrocatalysts. First, crystal structure, electronic properties, and ORR reaction mechanism are briefly introduced. Then some strategies for adjusting ORR performance of 2D TMDs are summarized, including heteroatom doping, phase conversion, defect engineering, and strain engineering. Meanwhile, the ORR activity enhancement arising from 2D TMDs-based heterostructures is also analyzed. Finally, perspectives are given for current issues and their possible solutions.

Piezoelectric ceramic is a type of functional ceramic, which is able to convert the mechanical signal and the electronic signal mutually. Composed of piezoelectric ceramics and organic phase, piezoelectric composites have different kinds of connectivities, which not only determine the diverse applications of piezoelectric devices, but also promote the development of various shaping techniques in manufacturing piezoelectric materials and devices. In comparison with the traditional shaping methods, the most distinguishable advantage of additive manufacturing lies in its ability of quickly shaping a small batch of samples into geometrically complex designs without a mould, which makes it a highly suitable technique for investigating piezoelectric ceramics and its derivative devices in different kinds of connectivities. Meanwhile, the final additively manufactured samples require only tiny post-processing, have a high rate of utilization of the raw material and do not need cutting fluid during manufacturing. Due to the above-mentioned advantages, it attracts the widespread concerns from both academic and industrial communities. When focusing in the field of additive manufacturing ceramics, the data of scientific reports in additive manufacturing functional ceramics and devices prove that it is still in a growing period. In the perspective of different additive manufacturing techniques, this article discusses and compares additive manufacturing of both lead-free and lead-based piezoelectric ceramics in the aspects of their historical development of each technique, preparation of the raw materials, geometrical designs, measurement of functional properties, and applications of the printed samples, and forecasts the future development based on the current benefits and drawbacks of each additive manufacturing technique.

As green rechargeable batteries, lithium-ion batteries feature high energy and power density. However, commonly-used electrolytes, organic compounds, in commercially available lithium-ion batteries are flammable and toxic, which leaves them at the risk of combustion and explosion when being overcharged or short-circuited. In order to solve this problem, much attention has been paid to lithium-ion batteries with aqueous electrolytes, which take low-toxicity and high safety as the prominent advantages. The working voltage, 1.5-2.0 V, indicates their usage mainly in the field of energy storage. Considering the hydrogen and oxygen evolution, conventional anode materials used in commercially available lithium-ion batteries are inconformity for water-based lithium-ion batteries. Therefore, the key to the development of aqueous lithium-ion batteries lies in the selection of anodes. The anode material, LiTi2(PO4)3, has drawn the attention of researchers due to its advantages such as three-dimensional channel, and appropriate lithium-ion intercalation potential. The synthesis methods of LiTi2(PO4)3 mainly include high temperature solid-phase calcination, Sol-Gel methods and hydrothermal reaction, etc. To further improve the electrochemical performance of LiTi2(PO4)3, strategies can be used such as particle nanocrystallization, morphology control, element doping, and carbon-coating, etc. This review focuses on the synthesis and modification of LiTi2(PO4)3, as well as related research progress. At last, the future development of LiTi2(PO4)3 as anode material for lithium-ion battery is properly prospected.

Flash sintering is an electric field assisted sintering technology which has attracted much attention in recent years. This review introduces its origin, development, and basic characteristics. In the study of flash incubation and initiation process, the nonlinear conductivity characteristics and electrochemical blackening phenomenon are narrated, and the defect mechanism dominated by oxygen vacancy is recounted. As for rapid densification during flash sintering, it is proposed that the generation and movement of defects caused by electric field produce Coulomb force between powder particles, which is conducive to density in the early stage of flash sintering. Meanwhile, the densification process is accompanied by the rapid movement of metal cations. In terms of grain growth and microstructure evolution during the flash sintering, the sample temperature is asymmetrically distributed along the current direction, and the internal grain boundary mobility in the sample is significantly improved. During this stage, electrochemical defects exert a significant impact on the microstructure. Based on the above researches, we developed ceramic flash joining technology by using phenomenon of low-temperature rapid mass transfer under electric field, and realized rapid joining between similar kind of ceramics/ceramics, ceramics/metals, and even dissimilar ceramics/ceramics. A new ultrafast ceramic synthesis technology by flash sintering was developed, which not only realized the rapid synthesis of typical oxide ceramics, but also realized the rapid synthesis of high entropy ceramics and oxide ceramics with eutectic morphology. An electroplastic forming technology of oxide ceramics was developed, and a rapid tensile and bending deformation of zirconia ceramics at low temperature and low stress was preliminarily realized. Finally, this review summarizes the challenges in the field of flash sintering mechanism, and looks forward to the development direction of flash sintering from two aspects of Joule heating effect and nonthermal effect, aiming to be beneficial to the development of flash sintering technology in China.

The electrocaloric effect refers to the phenomenon of the temperature change of a material caused by the application or removal of an electric field, and includes two types, positive electrocaloric effect and negative electrocaloric effect. As a high-efficiency, noise-free and environment-friendly refrigeration effect, the electrocaloric effect shows promising application in the field of solid-state refrigeration, especially in integrated circuit refrigeration, and has attracted extensive research interests over the past decades. It is reported that the cooling capacity of the electrocaloric effect can be significantly improved by combining the positive and negative electrocaloric effects. However, different from the widely studied positive electrocaloric effect, the research on negative electrocaloric effect is relatively rare due to its complex physical origin. This article focuses on the latest research progress of the negative electrocaloric effect in antiferroelectric materials. The specific content includes the following four parts. Firstly, starting from the research history of the electrocaloric effect, the principle of refrigeration of the electrocaloric effect is introduced, as well as a typical dual refrigeration cycle that can combine positive and negative electrocaloric effect. Secondly, the indirect measurement method of negative electrocaloric effect based on Maxwell relationship, and several direct measurement methods of negative electrocaloric effect, and the suitable applying conditions as well as the advantages and disadvantages of different methods are discussed. Thirdly, taking antiferroelectric which is a typical negative electrocaloric effect materials as an example, the physical origin of negative electrocaloric effect is narrated. Then the recent progress of negative electrocaloric effect in the antiferroelectric film and antiferroelectric bulk materials is reviewed. In addition, the negative electrocaloric effect in some other ferroelectric materials is also briefly introduced. Finally, a summary and prospect of the research on the negative electrocaloric effect are put forward.

Two-dimensional (2D) materials have brought about significant technological advancements in the field of biomaterials. Transition metal carbides and/or nitrides (MXenes) have a planar structure educed from their corresponding parent MAX phase by selective etching of ‘A’ and further delamination. Since the first MXene was reported in 2011, MXenes now comprise a rapidly growing family of 2D materials, having attracted extensive attention from researchers. Owing to their excellent electronic properties, outstanding photothermal conversion performance, high specific surface area, good biocompatibility, and low toxicity, MXenes have shown a good application prospect in tumor theranostics. This paper reviews substantive findings of the original researches focused on the preparation, property and application in tumor theranotics, including recent advances, challenges and future perspectives of MXenes. Firstly, we briefly summarize the preparation methods and property of MXenes, including HF acid method, fluoride salt method, molten salt method, alkali-assisted hydrothermal method, and chemical vapor deposition method, as well as stability, mechanical, optical, and electrical properties. Secondly, we focus on the application of MXenes in photothermal therapy and combined therapy. The usual method is to combine photothermal therapy, photodynamic therapy and chemotherapy to carry out multi-modal combined treatment of tumors. The combined therapy can also be improved by constructing surface nanopores of MXenes and loading chemotherapy drugs in them. Furthermore, enhanced MXenes synergistic therapeutic effect on tumor and reduced toxic side effects on normal tissue can be endued by active targeting technology. In addition, the preparation of multifunctional MXenes composite nanomaterials to obtain radiation treatment and imaging capabilities such as computed tomography scans and magnetic resonance imaging, can establish an integrated platform for MXenes theranostics. Finally, we briefly introduced other applications of MXenes in biomedicine which are beneficial to tumor theranostics, and elaborate the current challenges and future development prospects of MXenes in cancer theranostics.

With the development of mesoporous materials and biomedicine, hollow periodic mesoporous organosilicas (HPMOs), as a new type of mesoporous silicon material, stands out among many mesoporous materials because of its high specific surface area, high drug loading, good biocompatibility, multifunctional organic-inorganic hybrid framework, low cytotoxicity and biodegradability. Drug delivery systems based on HPMOs have been continuously developed, it provides a new strategy for tumor treatment. This article summarized the synthetic progress of HPMOs in recent years, briefly introduced the types of HPMOs, mainly expounded the hard template method, liquid interface assembly method and interface recombination-transformation method, and summarized its application in tumor therapy. Finally, challenges and future development trends as a drug carrier were prospected, in order to provide reference for the preparation and application of HPMOs in tumor therapy.

With the continuous deepening of research on nanomaterials, it has been applied in a wide range of technical fields, and has great potential to support new discoveries in basic sciences. Among them, nanomaterials composed of single elements are of particular interest because they are tractable and readily available in synthesis. Two-dimensional (2D) nanomaterials from Group VA single-element (including black phosphorus, arsenene) have broad application prospects in biological applications such as bioimaging, drug delivery, and diagnostic therapy due to their excellent physical, chemical, electronic, and optical properties. This review summarizes the general properties, synthesis, and modification methods of group VA single-element 2D nanomaterials, and then focuses on their various biomedical applications. Finally, challenges and future prospects of these nanomaterials in the field of biomedicine are discussed.

With the development of nanomedicine, utilization of nanomaterials to catalyze the generation of excess reactive oxygen species (ROS) under exogenous ultrasound stimulation has attracted widespread attention for disease therapy, which is called sonodynamic therapy (SDT). Currently, development of high-efficiency sonosensitizers that can be used in SDT to improve ROS yield remains one of the most important challenges for current research and future clinical translation. Recently, benefited from the development of piezotronics and piezophototronics, novel sonosensitizers based on piezoelectric semiconductor nanomaterials have shown promising applications in SDT. In this review, we outline the structures and properties of piezoelectric semiconductors, and introduce the presumed mechanism of SDT with piezoelectric semiconductors. The newest research progresses on using piezoelectric semiconductor as sonosensitizer in cancer treatments and antibacterial applications are summarized. Finally, the existing challenges and future development trends in this field are proposed.

The robust development of clinical medicine and biomaterials boosts diagnostic imaging, effective treatment, and precise theranostics in various diseases. The emerging interdiscipline of materials and medicine, termed as materdicine, aims to surmount the critical obstacles and challenges faced by traditional medicine, such as systemic toxicity, poor bioavailability, inferior site-targeting specificity, and unsatisfied diagnostic/therapeutic efficacy. Herein, the state-of-the-art advances regarding the applications of diverse medmaterials for disease diagnosis, therapy, and theranostics are systematically summarized in this review, especially focusing on the nanoscale medmaterials. We firstly emphasize and discuss biomedical imaging (e.g., optical imaging, magnetic resonance imaging, ultrasound imaging, computed tomography imaging) and therapeutic strategies (e.g., photothermal therapy, dynamic therapy, immunotherapy, synergistic therapy) in the field of cancer treatment. Furthermore, we highlight the important progress of medmaterials in the diagnosis and treatment of other kinds of diseases including orthopedic diseases, respiratory system, and brain diseases. Especially, the elaborated medmaterials for other representative biomedical applications, such as biosensing and antibacteria, are illustrated in detail. Finally, we discuss the current challenges and future opportunities for the practical application of these unique medmaterials in materdicine for accelerating their early realization of clinical translations, promoting the progresses of clinical medicine and benefiting the patients.

The triboelectric nanogenerator (TENG) is a kind of green power source which can harvest and transform small mechanical energy into electricity. Triboelectric nanogenerators have various active materials, simple structures, and easy to integrate with other devices. However, its relatively low output power density hinders the further practical application of TENGs. How to improve the output performance of TENGs through the modification of the active triboelectric materials is one of the hottest spots. It is a facile and effective way to introduce functional fillers into polymer substrates to fabricate composite materials, which improve the triboelectricity of pristine material and bring new functions for the device. Thus, composite films are widely used in TENGs. For example, inorganic fillers like TiO2, SiO2, BaTiO3, ZnSnO3, MoS2, r-GO sheets, and nanofibril-phosphorene have been introduced into polymers to improve the output power density of TENGs by dozens of times. Based on domestic and international research, this review introduces the applications of the composite film in TENGs. The improvements of TENGs induced by the fillers are discussed from two aspects: the surface property and electrical property. Finally, future challenges in developing composites based TENGs are prospected.

Fuel cells are highly efficient and green devices for direct chemical-to-electrical energy conversion. However, limited by slow kinetics of oxygen reduction reaction (ORR) in cathode, fuel cells require catalysts with noble metal like Pt, thus significantly increasing the cost of the fuel cells. Carbon-supported metal single atom catalysts (C-SACs) have excellent properties such as high atom utilization efficiency and selectivity. In addition, C-SACs show high ORR activity under different pH conditions, hence have been recognized as economical candidates to replace noble metal in fuel cells. This article reviewed the strategies used to improve ORR activity of C-SACs, including selecting different kinds of metal single atoms, tailoring coordination structure of metal centers, and heteroatomic doping to substrate. Performances of C-SACs in rotating disk electrode or battery device are also introduced. At last, the feasibility and potential challenges of C-SACs in practical application are prospected and summarized.

Due to high power, high brightness, small size, energy saving, and environment friendliness, solid-state lighting has been becoming the most promising lighting technology in this century. As the key material of solid-state lighting, the luminescent properties of phosphors directly determine the crucial parameters such as the color rendering index, luminous efficacy and reliability of solid-state lighting devices. Compared with single crystals, phosphor glasses, phosphor films and quantum-well LEDs, phosphor ceramics have become the most excellent phosphor materials for high-power solid-state lighting due to its excellent thermal and optical properties and easy control of microstructure. In the future, phosphor ceramics is expected to be more widely used and developed in automotive headlights, outdoor lighting, laser TVs, laser cinema projectors, and other fields, and have a broad market prospect. In this review, design principles of high-power solid-state lighting phosphor ceramics are put forward firstly, and then their research progress of oxide phosphor ceramics (mainly refers to Y3Al5O12) and nitrogen/oxynitride phosphor ceramics are reviewed mainly. Finally, the development of phosphor ceramics for high-power solid-state lighting is prospected.

Rare earth ions doped Gd2O2S scintillators are new type of oxysulfide scintillators, which have been developed since 1980s. The Gd2O2S matrix with cross section of high density and high thermal neutron absorption has high X ray and thermal neutron stopping capacity. The doping of different rare earth ions (Pr3+, Tb3+, etc.) shows fast decay or high light yield, which plays a very important role in application of scintillation. Composition control of oxysulfide is always a key problem to be solved in the synthesis process. However, the high melting point of Gd2O2S material and the serious volatilization of sulfur restrict the preparation of Gd2O2S single crystals, with high optical quality and excellent scintillation performance. Ceramic is the main application form of Gd2O2S scintillation material. Its pure phase Gd 2O2S phosphors with small particle size, narrow particle size distribution and low agglomeration is the key to sintering high quality scintillation ceramics. These ceramics prepared by simply increasing the sintering temperature produce a large number of sulfur vacancies and oxygen vacancies, decreasing the scintillation properties. Therefore, preparation of Gd2O2S scintillation ceramics usually need pressure assistance to increase the production cost. In this paper, their scintillation mechanism and research situation are introduced firstly. Then, their fabrication process, solution of defects removal, research status and applications in neutron imaging and medical X-CT fields are overviewed. Finally, we summarized the previous and prospected the future development of Gd2O2S scintillation ceramics.

Nano materials exhibit many excellent properties compared with macro scale materials due to their special properties at nanoscale. They exhibit good application prospects in various fields such as mechanics, acoustics, optics, magnetism, electricity, thermology and so on. In this fascinating field, biomimetic self-assembly technology of nano materials has become one of the main methods to prepare nano materials, which simulates the life activities in vivo and makes the nano materials spontaneously form stable structures based on the noncovalent bond interaction. The biomimetic self-assembly technology is an important technology in the “bottom-up” method, which is expected to replace the traditional “top-down” processing technology, and realize the construction of specific structure and function devices on the nanoscale by single atom or molecule. Moreover, although the bionic self-assembly technology is mainly chemical process, it also has physical process, and combines advantages of “bionics” and has characteristics of directional construction of nano materials, which is a hot research means of many interdisciplinary. This paper reviews different biomimetic self-assembly synthesis strategies for nano materials in morphology and performance control, including phase selective self-assembly of shielding effect, bionic self-assembly of biphase interface synergy effect, integrated fabrication of functional devices with field induced localization effect, photoinduced self-assembly and phase separation self-assembly driven by hydroxyl hydrogen bond. The characteristics of biomimetic self-assembled nano materials are summarized. This paper also introduced the application of self-assembly technology in sensors, surface Raman scattering, biomedical and other fields. In addition, the prospects for the development of biomimetic self-assembly technology of nanomaterials are prospected.

TaxHf1-xC(0 4000 K), high hardness (~ 30 GPa), low coefficient of thermal expansion, excellent oxidation resistance, and excellent ablation resistance. Over the past decades, some extreme conditions required for aerospace industry have greatly promoted the development of TaxHf1-xC materials, and dozens of literatures were published in this area. In this paper, the research progress of TaxHf1-xC solid solution ceramics was introduced in terms of powder synthesis techniques, densification methods and mechanism, mechanical properties at room temperature, thermophysical properties, oxidation and ablation resistance. Advantages and disadvantages of three common techniques (solid solution between metal carbides, carbonization reaction of metals, and carbothermal reduction of metal oxides) for synthesizing TaxHf1-xC powder as well as the difficulties in densification of TaxHf1-xC solid solution ceramics were analyzed. Influence of sintering process on microstructure and mechanical properties at room temperature of TaxHf1-xC solid solution ceramics was discussed briefly. The hardness, elastic modulus, KIC, melting point, thermal conductivity, coefficient of thermal expansion, oxidation and ablation behavior of TaxHf1-xC solid solution ceramics with different Ta/Hf ratios were summarized. It revealed that TaxHf1-xC solid solution ceramics will obtain a good performance on both mechanical properties and oxidation resistance when Ta/Hf was approximate 1. Furthermore, the remaining challenges and future outlook of TaxHf1-xC solid solution ceramics were also addressed.

As a nano-porous material with high porosity, low density, high specific surface area, excellent heat-resistance, and low thermal conductivity, the alumina aerogel shows broad application prospect in high-temperature thermal insulating areas such as the thermal protective system for space vehicles and the thermal insulation for industrial kilns. However, pristine alumina aerogels can’t be directly used because of their relatively poor thermal resistance above 1000 ℃, mechanical strengths and high-temperature thermal insulating performance. They need to be improved by introducing reinforcements and opacifiers (namely the alumina aerogel composite). This paper summarizes the latest research progress of synthesis of heat-resistant alumina aerogels, and preparation and properties of alumina aerogel composites. Researchers improved the thermal stability of alumina aerogels by modifications such as in-situ doping, deposition, organic chains or carbon coatings. The introduction of whiskers, particles, porous skeletons or fibers into alumina aerogels contributes to considerable improvement of mechanical performance. The cooperation of fibers and opacifiers help to increase the inhibition of infrared radiation and lower the high-temperature thermal conductivity of alumina aerogels. The future of alumina aerogel composites is also proposed: a) finely tailoring the bulk density, micro structures, and introducing proper foreign elements and opacifiers, are supposed to further optimize the thermal stability of alumina aerogels and thermal insulating performance of their composites; b) deeper attention should also be paid on the evolution of structure and properties of composites at elevated temperatures, and on the interaction between alumina aerogel and reinforcement. As a novel thermal insulation, alumina aerogel composites are expected to take their advantages and be widely applied in the future.

Metal organic frameworks(MOFs) nanofibrous membranes (NFMs) based on electrospinning technology integrate the advantages of inorganic porous materials and polymer nanofibers, enabling them a class of functional materials with broad application prospects. MOFs NFMs with different functions are explored continuously and their application fields are expanding. In this work, we briefly introduce the development of MOFs NFMs, which has experienced a gradual transformation from preparation research to application research. Then, the main methods on preparing MOFs NFMs, including mixed electrospinning, in situ growth, multistep seeded growth, and atomic layer deposition, are described in detail. The main application and of current MOFs NFMs, such as adsorption and separation, heterogeneous catalysis, sensing detection are expounded. And, we put forward the future prospect of the development directions and trends of MOFs NFMs.

Chabazite (CHA) zeolite membranes exhibit superior performances in light gas separations owing to the eight-membered ring channel structure with small pore size (0.38 nm), adjustable surface characteristics, and high material stability and preparation reproducibility, and have gradually become one of the hot spots of zeolite membrane research in recent years. This review article first introduces the basic characteristics, the two typical CHA zeolite membranes (SAPO-34 and SSZ-13 membranes), then compares the synthesis and preparation methods of CHA zeolite membranes (in-situ synthesis, secondary growth synthesis, microwave heating methods) and analyzes their advantages and disadvantages in application status. The influences of their key synthesis conditions of the secondary growth as the mainstream synthesis method on the qualities of SSZ-13 and SAPO-34 membranes have been elaborated in detail, mainly including 1) the seeding conditions, such as carrier type, seeding crystal and seeding approach; 2) the hydrothermal synthesis conditions, such as crystallization time and temperature, water content, silica-to-alumina ratio, structure directing agent, and cation type; 3) the calcination approaches, such as conventional calcination, staged calcination, and rapid heating treatments. After comparative analysis, the preferred synthesis of the above two typical CHA zeolite membranes are proposed. Furthermore, the modulation of membrane surface chemistry is discussed for the enhancement in gas separation, such as silica-to-alumina ratio adjustment, ion exchange, heteroatom substitution, amino-group functionalization, and surface modification. The detailed characteristics of gas separation in various gas mixture systems and the permeation properties of different single gases on CHA zeolite membranes are analyzed and summarized as well. Finally, the future development of CHA zeolite membranes is prospected.

In the production process of multicrystalline silicon solar cells, diamond wire sawn (DWS) cutting technology attracts wide attention because of its advantages of high cutting speed, high precision and less loss of raw materials. But the traditional acid etching technology cannot match the shallow damage layer formed on the surface of diamond wire sawn cut multicrystalline silicon wafer to make the texture surface. On the contrary, the metal-catalyzed chemical etching method owns the advantages of simple operation, controllable structure and easy to form the structure with high aspect ratio, indicating a wide range of application on diamond wire sawn cut multicrystalline silicon wafer. This paper systematically summarizes the work of the etching mechanisms and the structures of textures by different metal catalysts in the process of making texture surface, and deeply discusses the single and composite catalytic etching process of Ag and Cu, the structure of texture surface, and the performance of solar cells. Finally, the problems of metal-catalyzed chemical etching on the surface of diamond wire sawn cut multicrystalline silicon are analyzed, and their future research directions are prospected.

Recently, iron nanoparticles have become one of the main research materials for environmental remediation due to the excellent catalytic/reduction performance, low cost and environmental friendliness. At present, the research of iron nanoparticles mainly focuses on the heavy metal removal, organic pollution degradation, inorganic anion catalytic reduction in sewage system, etc. However, there still exist some problems, such as low removal efficiency, poor stability, and single removal on account of several self-defects of agglomeration and tedious structures. Hence, this review focuses on the following aspects: 1) controllable preparation of iron nanoparticles; 2) interface design of iron composites; 3) application of iron nanoparticles in heavy metals removal and electrocatalytic denitrification; 4) prospect of iron nanoparticles composites in environmental remediation.

As a new emergence material, high-entropy ceramics possess unique properties due to its high configurational entropy. Among these ceramics, high-entropy transition metal carbide ceramics (HETMCC) are expected to be the potential candidates for the thermal protection system of hypersonic aircraft. Compared with single-component ceramics, the comprehensive performance of single-phase HETMCC is greatly improved. At present, the research on HETMCC is still in the initial stage, and the composition design and theoretical analysis of HETMCC are lack of sufficient research support. In addition, it is necessary to further explore the preparation of high purity HETMCC. In terms of the properties of HETMCC, further in-depth research has been conducted. In this paper, the theoretical design and preparation methods of high-entropy ceramics are reviewed. Research progress of the mechanical properties, thermal conductivity, and oxidation resistance properties of HETMCC are introduced in detail. The concerned scientific issues of HETMCC are pointed out and their future development direction are also prospected.

As the extension of high-entropy alloy, entropy engineering has been already extensively used in thermoelectrics because it can guide the optimization of thermoelectric (TE) performance from the aspects of both electrical and thermal transports. Due to the inherent material gene-like feature, entropy can be used as a performance indicator to rapidly screen new multicomponent TE materials. In this review, we first reveal the reason why entropy can be used as the performance indicator of TE materials. The physical mechanisms of enhanced structure symmetry, improved Seebeck coefficient, and suppressed lattice thermal conductivity as a result of the increased configurational entropy are discussed. Then, the applications of entropy engineering in typical TE materials, such as liquid-like materials and IV-VI semiconductors, are outlined, and the approach to screen and identify candidate multicomponent TE materials with high configurational entropy is introduced. Finally, the future directions for entropy engineering are highlighted.

Environmental barrier coatings (EBCs) have been developed to improve the durability of SiCf/SiC CMC components against harsh combustion environment. Among the most promising EBC candidates, rare-earth (RE) silicates attract attentions for their low thermal expansion coefficient, excellent high temperature water vaper and CMAS corrosion resistance, and good thermal and chemical compatibility with silicon-based ceramics and composites. Herein, we reviewed the optimizations of critical key properties of rare-earth silicates through strategic high entropy design to modify the current performance deficiencies of rare-earth silicates like thermal properties (coefficient of thermal expansion and thermal conductivity), CMAS corrosion resistance and high temperature phase stability. The present advancements demonstrate the merits of high entropy engineering for advanced EBCs for the improvement of crucial properties in engine applications.

Bacteria-related diseases, environmental pollution and other issues have attracted enough attention. Meanwhile, with the use of antibiotics, bacteria evolved strong drug resistance forcing people to develop new antibacterial agents urgently. Natural enzymes such as lysozyme and myeloperoxidase have significant antibacterial ability. However, natural enzymes own limitations such as short shelf life and high production costs. Besides, they are difficult in applying to large-scale production. Therefore, people are seeking alternatives to natural enzymes. Nanozymes are a new generation of artificial enzymes which have unique physical and chemical properties of nanomaterials and enzyme-like catalytic activity. Because of structural stability and low production cost, they are widely explored. This article reviews the antimicrobial mechanism and the recent progress of nanozymes in antibacterial research, and, finally, gives some prospects for future research.

Ceramic fiber has the advantages of low density, high strength, high temperature resistance and good mechanical vibration resistance. It is the critical high temperature thermal insulation materials especially in thermal protection fields such as aerospace vehicles, nuclear power plants and chemo-metallurgical industry, etc. The traditional ceramic fiber with large diameter (> 5 μm), high brittleness and high thermal conductivity has been greatly restricted in high temperature thermal insulation fields. In recent years, more and more attention has been paid to the preparation of micro-nano ceramic fibers by decreasing the diameter of fiber, which is not only beneficial to improve the mechanical properties of the fibers, but also to enhance their high temperature thermal insulation properties. Further, by finely regulating the composition and structure of the micro-nano ceramic fibers that intrinsically affecting the heat transfer (heat conduction of gas, heat conduction of solid and radiative heat transfer) mechanism in micro-nano ceramic fibers, the high temperature thermal insulation performance can be effectively improved, which is the current focus of the micro-nano ceramic fibers in high temperature thermal insulation fields. The thermal insulation mechanism of the micro-nano ceramic fibers was firstly introduced. Then, based on the research at home and abroad, this review divides the current micro-nano ceramic fibers into three categories according to the difference of their composition and structure, namely fibers aerogels, hollow/porous fibers and composite fibers. The latest research progress on composition and structure optimization of micro-nano ceramic fibers for high temperature thermal insulation is reviewed, and the future development tendency is prospected.

Nanoscale tungsten oxide, as a functional semiconductor with unique physical and chemical properties, is widely used in environment, energy, life science and information technology fields. Based on the application of first-principles study in nanoscale tungsten oxide, the functions of theory calculations are reviewed in the paper. Firstly, the development and basic theory of the first principles and density functional theory are illustrated based on quantum mechanics. Then, the commonly related software in such field of semiconductors, such as MS (Materials studio) and VASP (Vienna ab initio simulation package) are introduced. Furthermore, the recent study of the first-principles on tungsten oxide in terms of electronic structure, interaction of materials, molecular thermodynamics, and so on, is clarified. Finally, the existing problems and future developments of theory calculations used in the field are summarized and prospected.

As an important branch of nonlinear optics, second harmonic generation (SHG) is becoming one of the most important means to characterize crystal structure. Among various methods of characterization, because of nondestructive detection, high stability, tunability, ultrafast response, polarization sensitivity, versatility and simplicity, SHG is widely used to characterize the structure of two-dimensional (2D) materials. It provides important information for the physical properties and functional applications of 2D materials, as well as greatly promotes the rapid development of basic research on 2D materials. Here, the current state of the art focuses on the recent research work of SHG in 2D material structure characterization. Firstly, the principle of the second harmonic generation is briefly introduced. Then, the second harmonic generation device with femtosecond laser connected to confocal Raman spectrometer is taken as an example to present the mechanism of SHG. Afterwards, the applications of SHG are demonstrated in the thickness of interlayer stacking of 2D materials, the stacking angle between different layers of 2D materials, the grain boundary and the crystal orientation of monolayer 2D materials. The second harmonic intensity is used as a direct and sensitive means to monitor the strain amplitude, and the SHG signal changes are used to track defects in materials. Meanwhile, the importance of multi-dimensional correlation analysis of second harmonic generation, Raman spectroscopy and photoluminescence in comprehensive and in-depth characterization of materials is also explored. Finally, the potential research directions and prospects based on SHG in material characterization in the future is prospected.

Vanadium dioxide (VO2), as a transition metal oxide, has thermochromic property, which undergoes metal to insulator transition (MIT) in response to external temperature changes, and is accompanied by numerous changes in physical property. It has attracted widespread attention in the field of smart windows. In recent years, research on the preparation method of VO2, the phase change mechanism, and the improvement of optical performance are quite rich. However, practical applications still face technical bottlenecks and challenges such as higher intrinsic transition temperature (Tc), lower luminous transmittance (Tlum), insufficient solar modulation ability (ΔTsol), nonideal metastability and durability, and uncomfortable color for human eyes (brownish yellow). At present, there are many researches related to the improvement of the performance of VO2 itself owing to its insufficient optical property, and general methods for improving its performance such as elements doping, multilayer film structure design, and microstructure design have been widely adopted. This review summarizes the general performance improvement strategies of VO2 film, and highlights the latest research progress of VO2-based smart window service performance, low-temperature flexible preparation and color modulation in practical applications. Future development trends are also discussed in terms of skin comfort and environmental friendliness.

Chemotherapy is the main method used for cancer treatment. However, most chemotherapeutic drugs show low selectivity towards tumor cells. When killing tumor cells, chemotherapeutic drugs can also damage normal tissue cells and induce a series of side effects and toxic reactions, such as gastrointestinal reactions, calvities and so on. An effective way to reduce the adverse drug reactions is to construct targeted delivery systems based on the microenvironment properties of tumor tissue. Porous carbon nanomaterials (PCN), with excellent properties such as good structural stability, pores, and easily modified surface, are promising candidate to be used for such strategy. In this paper, the construction and application of the PCN-based targeted antitumor drugs delivery system were reviewed; the structural properties, the design philosophy of PCN suitable for drug loading were summarized; the effective strategies to improve drug loading on PCN for combined drug delivery were discussed both theoretically and experimentally. The mechanism and applications of PCN for tumor microenvironment based targeted delivery system were analyzed from the perspectives of endogenous sensitive stimulations (such as acidity, redox potential and specific enzyme), exogenous sensitive stimulations (such as light and magnetic) and multiple sensitive stimulations (such as double sensitive stimulations, including acidity/redox potential, acidity/magnetic and magnetic/light, and three sensitive stimulation, including acidity/redox potential/light). The biocompatibility and biodegradability of PCN used as anti-tumor drug delivery system was discussed, and the possible solutions were analyzed. The prospects of the application of PCN to be used in tumor drugs were discussed at the end of this review. This review provides theoretical basis and examples towards design and synthesis of porous carbon (PC) materials based anti-tumor drug delivery system, which may help the research and development of targeted and controllable tumor treatment.

The production of nuclear energy, the development of nuclear energy, and the development of nuclear weapons inevitably produce radioactive waste among which the existing high-level radioactive waste is one of the most difficult to deal with. With the implementation of “actively developing nuclear power” strategy in China, the safe and effective disposal of radioactive waste has become a key issue in addressing the sustainable development of nuclear power. SYNROC solidification is considered as the ideal medium material for the second generation of solidified high-level radioactive waste. Based on the review of the concept of synroc solidification and the classification of candidate mineral host, we mainly introduce the latest research progress in the rapid synthesis method of SYNROC, the nucleation mechanism, and the long-term stability evaluation, in the path that though the road is hindered and long, the line is approaching if striving forward. Finally, the existing weakness of SYNROC curing is pointed out, and the research direction and development trend that should be paid attention to in the future are proposed.

Hydrolysis is a unique method for hydrogen generation at ambient condition. Widespread attentions have been paid to materials for hydrogen generation via hydrolysis due to several advantages: high theoretical hydrogen capacity, moderate storage and operation condition, safety, etc. In this paper, recent progress and development in this area were reviewed. Three types of materials including borohydride (NaBH4, NH3·BH3), metal (Mg, Al), and metal hydride (MgH2) were introduced. Several issues about them were discussed specifically: mechanism, main problems, designments of catalysts and materials, etc. Based on these discussions, we compared the different materials mentioned above, commented their current performances and practical difficulties. At last, prospects in this field were presented.

In recent years, the development of new energy vehicles industry is accelerating. Lithium nickel cobalt manganese/aluminum oxide ternary cathode materials (NCM/NCA), especially with the nickel content ≥50%, has aroused great interest in both academia and industry. This is mainly due to the fact that the aggregative parameters of performance and cost of NCM/NCA are superior to those of traditional cathode materials, such as LiCoO2 and LiFePO4. However, the application of NCM/NCA is affected by a number of drawbacks, including poor safety and insufficient cycle stability and so on, which are mainly attributed to its crystal and surface structure. Researchers have carried out various efforts to solve these problems and further improve the performance of NCM/NCA. Some remarkable results have been achieved in the past few years. In this review, the latest research progress on coating and doping of Ni-rich ternary cathode materials is summarized from the view on the mechanism of structural and electrochemical improvement of NCM/NCA. Finally, the perspective for the development of NCM/NCA cathode materials is also prospected.

Membrane-based gas separation is one of the critical technologies in filtration and separation industry, since it is more efficient, energy-saving and environmentally friendly compared with traditional separation technologies. Novel inorganic two-dimensional materials (2DMs) for gas separation are expected to achieve both high selectivity and high permeability, breaking through the trade-off between selectivity and permeability of commercial polymer membranes. This review begins with a brief explanation of gas separation mechanisms for membranes. Afterwards, special attention will be given to the recent advances in novel inorganic 2DMs including graphene and their derivatives, TMDs and MXene, about their design, fabrication and application in gas separation. The gas separation characteristics of different materials, their challenges and directions for future research are summarized. Moreover, the application of other novel inorganic 2DMs, such as LDH, h-BN and mica nanosheets in gas separation technology is also discussed. Finally, the perspectives and challenges for future research of novel inorganic 2DMs in gas separation field are outlined.

Porous bioceramic scaffolds, which possess attractive biocompatibility, ability to guide tissue regeneration and porous surface morphologies and channels beneficial to ingrowth of new born tissues, have seized increasing attentions and been widely applied in the field of hard tissue restoration. Whereas, the weak osteoinductive activity, monotonous biological function and poor mechanical property have restrained the therapeutic efficacy and wider application of bioceramic scaffolds. In view of this, we intended to introduce the existing modification methods of bioceramic scaffolds, including the surface modification with functional coating, construction of surface micro-/nano- structures, functional element doping and enhancement of mechanical property, along with the state of the research progresses in the improvement of biocompatibility, bone defect restoration, drug delivery, tumor therapy, and antibacterial capacity of multifunctional bioceramic scaffolds. In addition, potential research directions and applications of functionally modified bioceramic scaffolds are prospected to provide references for the related exploration afterwards.

Dynamic mechanical analysis (DMA) has the advantage of high sensitivity, excellent cooling system, flexible rotation testing part, multiple deformation mode, and continuous frequency and temperature scanning mode. DMA is able to characterize the strain response under alternating stress, creep, stress relaxation, and thermomechanical properties, which has application in the investigation of plastic, thermoset, composite, high elastomer, coating, alloy and ceramic. This paper briefly introduced the fundamental and method about DMA, the application of DMA in the investigation of ferroelectric-paraelectric phase transformation, low frequency relaxation, ferroelectric fatigue, and ferroelectric composite damping. In the measurement of relaxation behavior of PZT ceramics and single crystals, and BaTiO3 ceramics, DMA tended to be more sensitive than dielectric characterization especially in the low frequency range. DMA has been one of the critical instruments for ferroelecric investigation.

The stable and reliable red phosphor with high-photon energy emission (620-650 nm) is critical for the fabrication of the phosphor-converted white light-emitting diode (WLED) with low correlated color temperature and high color rendering index. Mn 4+-activated phosphor is an emerging kind of red-emitting phosphor for WLED. Herein, the energy levels transition and photoluminescence characteristics of the Mn 4+ ion were introduced; then, the preparation, crystal structure and luminescent properties of as-far reported seven kinds of Mn 4+-doped oxyfluoride red phosphors (such as Na2WO2F4:Mn 4+) containing d 0, d 10 or s 0 cations were reviewed. Currently, only in quite rare case of oxyfluoride, Mn 4+ was found to exhibit strong R-line emission, with local coordination remaining as either [MnF6] or [MnO6]. The studies on the chemical stability and quantum efficiency of Mn 4+-doped oxyfluoride phosphors are still insufficient. Finally, we prospected the future development of Mn 4+-doped oxyfluoride phosphor.

With continuous development of electronics, the requirements for power supply systems are increasing. Supercapacitors (SCs), which have high energy density and excellent power output performance, are ideal power supplies for new generation of miniaturized, intelligent and wearable electronic devices. Thus, developing SCs with fast charge-discharge speed and high stability is a key research topic in the field of energy storage. As the most important part of SCs, electrode materials are critical to its performance. Due to the excellent performances of high-ordered pore structure, large specific surface area, diverse morphologies and dimensions, and adjustable conductivity, conductive metal-organic frameworks (MOFs) materials have shown great potential as promising SCs electrode materials, and have attracted wide attention. This review introduces the structure, conductive mechanism and preparation methods of conductive MOFs following a short introduction of SCs, describes its design strategy as SCs electrode materials, reviews the research progress of conductive MOFs in the field of SCs, and prospects its future application.

In recent years, zirconia ceramic, as a preferential choice for teeth restorations, is used as fixed partial dentures and implants due to its excellent mechanical properties, favorable biocompatibility and aesthetic properties, thus significantly shortening the performance life and seriously damaging the reliabilities. However, zirconia ceramic easily occurs low temperature degradation (LTD) of t-m transformation in humid environments. This paper illustrated the characteristics, mechanism and kinetics of LTD, as well as the conventional characterization methods of LTD phenomena and new methods such as optical coherence tomography and focused ion beam. It is also shown the main factors affecting the aging phenomenon, and emphasized the inhibition methods of LTD. By developing materials system and improving processing technology to enhance the strength, fracture toughness of zirconia and to solve the LTD of zirconia, and to meet the needs of people for their health functionalization, zirconia ceramic will be widely applied in the dental restoration field.

High-entropy ceramics, a novel class of single-phase ceramic solid solutions consisting of near-equimolar multielement species, are recently attracting tremendous attentions. Especially, the transition metal non-oxide high-entropy ceramics, such as transition metal carbide and boride high-entropy ceramics, have been proposed for potential applications in aerospace, nuclear energy, high-speed machining and many other extreme environments, owing to their excellent physical and chemical properties including super-high hardness, low thermal conductivity, good oxidation resistance and corrosion/erosion resistance. Recently, the research of high-entropy ceramics is only focused on composition design, fabrication methods, single-phase stability and mechanical properties, but the design criterion and theoretical analysis are rarely reported. Based on the researches of high-entropy alloy, the fabrication, characterization and theoretical study of several transition metal non-oxide high-entropy ceramics are summarized, along with some related results of high-entropy film. The prospects for the future developments of high-entropy ceramics are also discussed.

Two-dimensional materials have attracted broad interest because of their wide variety of properties. They can be used as photocatalysts and electrocatalysts due to their extremely high specific surface area, and have great potential application in the field of environment and renewable energy. This review focuses on the structure and properties of common two-dimensional materials such as 2D carbides and nitrides (MXenes), g-C3N4 and black phosphorus (BP). Furthermore, the latest research on the modification of two-dimensional materials in the area of photocatalysis and electrocatalysis are discussed and commented. Finally, research prospects for two-dimensional materials in the future are predicted.

Semiconductor photocatalytic water splitting has been considered as a potential strategy to overcome global energy shortage and environmental pollution. In recent years, phosphorene (BP) attracted great attention in photocatalytic water splitting due to its adjustable band gap, high hole mobility and wide absorption spectrum. This review summarizes the recent significant advances on designing high-performance BP-based photocatalysts for water splitting. The synthetic methods and modification strategies (e.g., surface modification and heterostructure design) of BP-based photocatalysts are described. Furthermore, in order to elucidate the structure-activity relationship of BP-based photocatalysts, the charge transfer mechanism is illustrated. Finally, the ongoing challenges and opportunities for the future development of BP-based photocatalysts in the exciting research area are highlighted.

Solid-state cooling technology based on the electrocaloric (EC) effect is attracting increasing attention as an important alternative for traditional cooling systems because of its advantages of high efficiency, environmental friendliness, light weight, low cost, and easy miniaturization. Ferroelectric materials are suitable candidates for EC refrigeration due to their large polarization and entropy change through applying or removing an external electric field. Recently, study on the EC effect of lead-free bulk ceramics has become one of hot topics on ferroelectric community due to the requirements of sustainable development. In this review, we firstly introduce the significant history events in EC research and the basic principles of EC refrigeration. Then, design strategy for achieving a large EC temperature change near room temperature and a wide using range is summarized. Subsequently, we systematically review the research status of EC effect in BaTiO3-based, Bi0.5Na0.5TiO3-based and K0.5Na0.5NbO3-based lead-free bulk ceramics and discuss their advantages as well as challenges. Finally, we propose some prospects for the future work on EC effect in lead-free bulk ceramics.

As smart electronic products are increasingly applied in our daily life, there is not only an increasing demand for high-performance photovoltaic power generation devices, but also strong need for in-situ energy storage functions in these devices. The integration of energy generating components and energy storage components into one device has become an attractive challenging technology. The basic idea is that by integration design and engineering the assembly of the photoelectric conversion layer and the energy storage layer into one in-situ energy conversion and storage system could not only offer multiple functions, such as self-powered ability, weak light buffer and portability, but reduce sunlight fluctuation effect on energy output. This review summarizes the research progress in novel in-situ integrative photovoltaic-storage tandem cells, classified by silicon solar cell, sensitized solar cell and perovskite solar cell. Evaluation of methodology, operational principle, construction feature, and performance parameter are also discussed and critically reviewed, and the further development of in-situ integrative photovoltaic-storage tandem cell is also prospected.

The third generation SiC fibers have near-stoichiometric composition and polycrystallinity with high density. Compared with the first and second generations, they have obvious improvements in heat-resistance, creep-resistance and radiation-resistance. Accordingly, they have more advantages and broader prospects in engineering applications, especially in the nuclear field. In this paper, the fabrication and performance characteristics of the third generation SiC fibers are introduced and compared. The applications of the third generation SiC fibers in the field of nuclear energy are reviewed, and the development prospects are prospected.

Chromogenic materials are capable of optical change reversibly in response to physical stimuli (e.g., electric field, temperature, illumination, and atmosphere). Among them, electrochromic materials are expected to be widely used in smart windows, screen displays, multi-functional energy storage devices and other fields due to their characteristics such as large adjustment range, fast response rate, high coloring efficiency and good cycle stability. However, compared with semi-solid-state electrochromic devices that are difficult to package and organic electrochromic materials that are prone to denaturation and failure, inorganic all-solid-state electrochromic materials and devices have better comprehensive application. This paper focuses on the typical inorganic all-solid-state electrochromic materials and devices, presents a brief review on the current preparation methods of each structure layer of electrochromic devices and compares its advantages and disadvantages, introduces in detail the main alternative electrochromic materials and its key performance evaluation index, and explains the principle of several representative electrochromic devices, proposes to use transparent flexible electrodes with both high light transmittance, low surface resistance and excellent bending fold to replace the traditional rigid substrate in order to realize multi-field responsible device application development. Finally, the application prospect of inorganic all-solid-state electrochromic devices is prospected from the perspective of performance bottleneck, process difficulty and industrialization opportunity, which provides reference for the industrialization process of electrochromic devices.

Proton Exchange Membrane Fuel Cell (PEMFC) has the characteristics of high energy conversion efficiency, high power density, fast start-up at room temperature, low noise and zero pollution, which is expected to alleviate the energy crisis and reduce carbon dioxide emissions. It has broad application prospects in rail transit, aerospace and other fields. Catalyst is one of the key materials of PEMFC. Moreover, Pt catalysts are widely used and considered difficult to be replaced because of their good activity and stability in oxygen reduction reaction. Pt is expensive because of its limited storage. However, Pt loading could be significantly lessened by Pt support to improve PEMFC utilization. Carbon materials are widely used as Pt supports because of their low cost, high specific surface area, pore structure, adjustable conductivity and surface properties, but commercial carbon black supports have low utilization efficiency and poor electrochemical corrosion resistance for Pt. For realizing the large-scale application of PEMFC, it is necessary to develop new carbon supports which can uniformly disperse Pt, efficiently utilize Pt, be resistant to electrochemical corrosion, and have good conductivity, thus the performance and sustainability of PEMFC are improved. Carbon aerogels, carbon nanotubes, graphene and other new carbon supports with unique structures and properties, which are expected to improve PEMFC performance and life, have attracted the attention of many researchers. In this paper, the research progress on new carbon material as Pt support for PEMFC in recent years is reviewed systematically, and the development trend is also commented appropriately.

It is a worldwide challenge to simultaneously improve the strength and damage tolerance of ceramics, which is a core issue in the development of ceramics and a goal pursued by materials scientists. While the pre-stressed design has been widely used to improve the strength of concrete and glass for over a century, a little progress has been made for ceramic materials. In this paper, the research progresses of ceramic reinforcement are summarized, and a new pre-stressed design and model of high strength and high damage tolerance composite ceramics are proposed. The novel design focuses on the generation of residual compressive stresses on the surface of ceramic components to inhibit crack initiation and growth, and offset the external tensile stress, which can be applied to different fields such as structural ceramics, architectural ceramics, domestic ceramics and so on. This simple and economical technique with no limitation of size and shape in ceramic components has great application prospects.

For the future advanced nuclear fuel cycle system, pyrochemical technology based on molten salt electrolysis is generally considered to be one of the most promising and reliable reprocessing technologies. The salt-containing waste generated in each step of the pyrochemical process needs to be converted into a ceramic waste form, which can be stably disposed in a long term manner in deep geological repository. This is of pivotal importance for the scale-up and industrialization of molten salt electrolysis based pyrochemical processing. In this review, the current research progresses of ceramic solidification technology in main nuclear energy countries with respect to salt-containing wastes were summarized and reviewed, with emphasis on ceramic solidifications of salt-containing wastes from electro-reduction process in LiCl-based salt and electro-refining process in LiCl-KCl salt. In addition, future perspectives in this field are also given.

Graphitic-like carbon nitride (g-C3N4), one of the most significant two-dimensional layered materials, has attracted worldwide attention in multidisciplinary areas such as photocatalysis, energy conversion and environmental pollution management. Its derivative compounds have also attracted multifarious attention owing to the intrinsic characters of their stable physicochemical properties, low cost and environmentally friendly features. This review focus on the design of high-performance g-C3N4-based nanomaterials and their potential for pollutant elimination in environmental pollution cleanup. Over the past few years, significant advances have been achieved to synthesize g-C3N4 and g-C3N4-based nanomaterials, and their properties have been enhanced and characterized in detail. In this review, recent developments in the synthesis and modification of g-C3N4-based nanomaterials are summarized. The applications in heavy metal ions adsorption from wastewaters are gathered and their underlying reaction mechanisms are discussed. Finally, a summary and outlook are also briefly illustrated.

Bacterial cellulose (BC), an eco-friendly bio-product obtained from fermentation of various microorganism, consisting of the interconnected networks structure attracted widespread interest due to its unique physical properties, including the large specific surface area, remarkable mechanical strength, high water-holding ability, good chemical stability, and environmental benign material. These advantages enable BC to be applied to fabricate the highly versatile three-dimensional (3D) carbon nanomaterials, and tunable flexible scaffold to support other multifunctional materials. In this review, the production process of various carbon nanofibrous composites based on BC, such as carbon nanofiber (CNF), doped CNF, CNF/metal oxide and CNF/conducting polymer, is presented. Their emerging applications in supercapacitors are illustrated, in particularly, the design of hybrid bendable electrodes based on BC substrate for flexible supercapacitor is highlighted. The challenges and opportunities in this fascinating area of designing functional nanomaterials and flexible electrode from BC for various energy storage are addressed. Moreover, the perspectives are given for the future development, including several significant kinds of study for applications in the rechargeable battery.

Graphene, as a representative of two-dimensional (2D) materials, has excellent intrinsic properties such as high specific surface area and conductivity, but its macroscopic bulk behaves poorly owing to severe face-to-face restacking and hand-in-hand contact resistance. Three-dimensional (3D) design of 2D materials can deliver the excellent nanoscaled properties to the macroscopic world, to realize the high surface area, conductivity, interconnected pores, and good mechanics of the bulks. It is necessary and highlighted to develop the porous monolith of 2D materials for applications as electrodes, adsorbents, elastomers, etc. The blowing route has the advantages of low cost and simple processing, which has been accentually developed to produce the foams of 2D materials for several years. This article introduces the principle of the blowing method, summarizing the recent examples of blown foams of graphene, boron nitride nanosheet, and others. The scientific front about foams of 2D materials is discussed, and the broad applications of the new materials are prospected in energy, environment, etc.

As an important transition metal oxide, manganese dioxide (MnO2) has attracted more and more attention due to its abundant reserves, varied crystal types and excellent material properties. Nanostructured MnO2 has smaller size and larger specific surface area, that makes it can further optimize its material properties and expand its application fields. In the introduction, this article starts with the introduction of the application of manganese dioxide, and points out that nanostructuring and variability in crystal form have an important influence on the structure and properties of manganese dioxide. The main text summarizes and reviews the research progress in recent years from two aspects: the preparation methods and the applications of nanostructured MnO2. (1) This paper introduces the progress in the preparation methods of nanostructured MnO2 including hydrothermal, Sol-Gel, chemical precipitation, solid-phase synthesis. Then the advantages and disadvantages of preparation methods, the morphologies and properties of nanostructured MnO2 are summarized. (2) The applications of nanostructured MnO2 including energy-storage electrodes, electrochromic devices, catalysts and bio-sensors are reviewed. Nanostructured MnO2 can be used as the cathode material of batteries and the electrode material of supercapacitors. Manganese- containing composite oxides prepared by adjusting the crystal form of MnO2 and compounding are used as the cathode material of the lithium ion batteries, which can increase the capacities and improve the cycle stability of batteries. It has been industrialized as a cathode material for lithium-ion power batteries, and has good application prospects in the field of new energy vehicles. As the electrode material of electrochromic devices, MnO2 is usually used by combining with other materials with large optical modulations since the color of pure MnO2 mainly changes between brown and yellow and its optical modulation is small. For example, polyaniline/MnO2 hybrid electrochromic film has a great difference in morphology, structure and electrochromic performance compared with pure polyaniline film, showing higher optical modulation, coloration efficiency and cycle stability. Nanostructured MnO2 plays important roles in the catalytic conversion of ethylbenzene and the catalytic elimination of air pollutants. Nanostructured MnO2 can increase the current response, reduce the detection limit, and greatly improve the sensitivity of detection. In recent years, it has been gradually paid attention to and widely used in the field of biosensors. For example, MnO2 nanosheets assisted fluorescence polarization biosensors can be effective in detection of Ag+ in environmental water samples, PtAu-MnO2 binary nanostructures modified graphene paper show good sensing performance in non-enzymatic glucose detection. In conclusion part, current existing problems are analyzed. The development direction of nanostructured MnO2 applied in lithium-ion battery cathode materials and electrochromic devices are pointed out. The future prospects for development of nanostructured MnO2 are discussed.

Anode material is an important component for Li-ion battery. The current anode materials are mainly based on graphite, which possesses low theoretical specific capacity of 372 mAh/g, and thus hinder the further development of Li-ion battery. Among the newly developed anode materials, metal oxides have recently attracted intense attention due to their high theoretical specific capacity, low cost and environmental friendliness. However, metal oxides own poor electrical conductivity and large volume changes during cycling. Nanosizing can overcome these disadvantages while maintaining the advantages for metal oxide based anode materials, and thus becomes a research hot spot. Herein, we review the recent research advances of the nanostructured metal oxides as anode materials, mainly focusing on the microstructure design and performance optimization of representative metal oxides and their composites. In addition, some suggestions are presented for further explorations in relative fields.

Owing to high X/γ-ray absorption coefficient, high carrier mobility lifetime product, and low temperature solution growth, halide perovskites emerged as promising room temperature radiation detector materials, which outperform traditional high-purity Ge and CdZnTe materials in term of low-cost, chip compatibility and large-area imaging. Starting from the fundamental properties of halide perovskites and the principle of radiation detectors, the development of halide perovskite radiation detectors since 2015 was briefly introduced. Then, recent progresses of direct radiation detectors (intensity, imaging, energy spectroscopy) and indirect scintillator detectors were systematically reviewed, and the crucial factors for high-performance detectors were discussed, which could provide valuable guidance for further boosting performance of halide-perovskite-based radiation detectors in future.

Boron nitride aerogel is a kind of new nanomaterials with three-dimensional porous network structure, which takes solid as the framework and gas as the dispersion medium. It has high specific surface area, high porosity, low density and other excellent properties. In addition, compared with graphene aerogels, it exhibits better insulation, oxidation resistance, thermal stability and chemical stability. These outstanding properties make it promising application in the fields of gas adsorption, catalysis, sewage purification, thermal insulation/conduction. This article systematically reviewed the preparation methods of boron nitride aerogels including the hard template method, soft template method, low-dimensional boron nitride assembly method, and template-free method in the light of domestic and foreign research status. Moreover, the important applications of boron nitride aerogels in key fields are summarized, and the future development direction is prospected.

Uranium dioxide is a potential multi-functional material as well as nuclear rod. It exhibits excellent semiconductor performance and anti-irradiation ability. It has the similar band gap (1.3 eV) of silicon crystal (1.1 eV), its Seebeck coefficient is 4 times of the commercial thermoelectric material BiTe, and it shows higher conversion efficiency of solar cells due to its nearly full absorption. These properties make it great potential applications in the fields of semiconductor, solar energy and thermoelectricity. However, the U atoms in uranium dioxide (UO2±x) can vary from -0.5 to 1, which is called hyperstoichiometric characteristics, resulting in some problems in crystal growth and property homogeneity. In this paper, we analyzed the structure and chemical stability of uranium oxides according to U-O phase diagrams, summarized recent research progress on crystal growth and physical properties of UO2 crystals. UO2 is an ideal Mott insulator with a stable electric conductivity, while the hyperstoichiometric UO2±x crystals are semiconductors, and their physical properties, including electric conductivity, thermal conductivity and diffusion coefficient, and optical properties, are closely related to x. So far, UO2 crystals have grown via several methods, such as chemical vapor transport (CVT), sublimation, skull melting, hydrothermal and flux. The skull melting and hydrothermal techniques are expected to improve crystal dimensions and quality in future. The growth of UO2 crystals is expected to enhance the understanding of the material and provide the possibility of great potential applications in solar cells, thermoelectric devices and future electronics.

All inorganic perovskite nanocrystals with narrow-emission, high quantum efficiency and high carrier mobility have been widely applied in the fields of light emitting diodes and solar cells. However, present surface ligands of the perovskite nanocrystals are in a dynamic bonding state, which easily fall off during separation and purification processes, resulting in the deterioration of quantum efficiency and stability. Besides, the ionic characteristic of halide perovskites makes it extremely sensitive to polar solvents. These disadvantages severely restrict the practical application of perovskite nanocrystals in optoelectronic devices. In this review, based on the surface state of perovskite nanocrystals, the effects of passivation strategies with Lewis acid, Lewis base and surface coating on optical properties, and stability of CsPbX3 perovskite nanocrystals are analyzed in detail combined with the domestic and abroad research work. Further optimization and improvement of the stability of CsPbX3 are prospected.

During charge and discharge of lithium-ion battery, the concentration gradient produced by lithium- ion diffusion process and deformation caused by lithiation expansion of the active material result in diffusion-induced stress. Excessive diffusion-induced stress can cause various mechanical failure modes such as cracking of active particles, separation between active particles, fracture of active layers, and delamination between active layers and current collectors, which eventually leads to a series of failure phenomena such as capacity attenuation, impedance rise and cycle life loss of the battery. Therefore, the diffusion-induced stress and the derived failure mechanism of lithium-ion battery become one of the research hotspots in the field of lithium-ion batteries, which has important theoretical and practical value. In this paper, research progress of the failure mechanism of lithium-ion battery caused by diffusion-induced stress in recent years is reviewed from different levels of the active particle, the active electrode, the half-cell, the cell unit, and the cell. The generation mechanism and research methods of diffusion-induced stress are introduced. The influence of diffusion-induced stress on the mechanical and electrochemical properties of the battery is analyzed, and the influencing factors of the diffusion-induced stress are summarized. Finally, the future research directions and development trends are prospected.

With the development of wearable flexible electronic technology, the demand for flexible sensor with high sensitivity and wide sensing range is gradually increasing. The application of suitable conductive materials with high electrical conductivity and high flexibility as sensitive materials for sensors is the key to obtain high performance sensors. In recent years, MXene materials have become very promising sensitive materials due to their good conductivity, high flexibility, good hydrophilicity, and controllable synthesis. The types of MXene-based flexible force sensors, microstructure design of sensitive materials, sensing performance, and sensing mechanism analysis have been expound and summarized in this paper.

Ceramic matrix composites (CMCs) are promising candidates for application in aeroengine, aerospace aircraft thermal protection systems, nuclear power system, and other fields. At present, CMCs are developing from structural bearing materials to multi-functional composites. MAX phases are a group of layered ternary ceramics with excellent plastic deformation capacity, high electrical conductivity, good irradiation resistance and ablation resistance. Besides strengthening and toughening CMCs, the introducing MAX phases into CMCs can effectively improve the anti-irradiation, anti-ablation and electromagnetic interference shielding performance, meeting requirements of multi-functional CMCs. This paper reviewed the progress on MAX phases modified CMCs, design mechanism and application prospect.

Phase diagrams, also known as equilibrium phase diagrams, serve as a road map for materials design. However, preparation process of coatings (such as Physical Vapor Deposition, PVD) is generally far from equilibrium and results in metastable phases. Thus, the CALPHAD (Calculation of Phase Diagrams) approach faces a challenge in calculating the metastable phase diagrams for PVD coating materials. Here we summarized the development of the modeling methodology for the metastable phase diagrams, where the model with critical surface diffusion distance established in recent years were highlighted. The CALPHAD approach, first-principles calculations coupled with high-throughput magnetron sputtering experiments were used to model the atomic surface diffusion, while only one key combinatorial experiment was performed to obtain the basic data for the computation, and the calculated metastable phase diagrams were confirmed by further experiments. Therefore, the database of the stable and metastable phase diagrams can be established, which will be used to guide the design of the ceramic coating materials by the relationship of composition, processing, microstructure, and performance. This model can also help to achieve the goal to shorten the time and reduce the costs of materials research and development.

In recent years, ternary layered carbide/nitride MAX phases and their derived two-dimensional nanolaminates MXenes have attracted extensive attention. The crystal structure of MAX phase is composed of Mn+1Xn unit interleaved with layers of A element. MAX phases combine good properties of metal and ceramic, which makes them promising candidates for high temperature structural materials, friction and wear devices, nuclear structural materials, etc. When etching the A-layer atoms of the MAX phase, the two-dimensional nanolaminates with the composition of Mn+1XnTx (Tx is surface termination), i.e. MXene, is obtained. MXenes have wide range of composition, and tunable physical and chemical properties, which endow them great potential in the applications of energy storage devices, electromagnetic shielding materials, and electronic devices, etc. In this paper, the research progress of MAX phase and MXene was introduced in terms of composition and structure, synthesis methods, and properties and application. Furthermore, the research prospects of this large family of materials were discussed.

All-solid-state lithium battery (ASSLB) with inorganic solid state electrolytes is one of promising candidates for electric vehicles and large-scale smart grids for storage of alternative energy resources due to their benefits in safety, energy density, operable temperature range, and longer cycle life. As the key component in ASSLB, inorganic lithium-ion-based solid-state electrolytes (SSEs), especially the garnet-type solid electrolytes that own ionic conductivities in the order of 10 -3 S·cm -1 at room temperature and are relative safe vs. Li metal, have obvious advantages in ASSLB. However, interfacial instability and their poor solid-solid contact between garnet and cathode result in high interfacial resistance, low efficiency, and poor cycle performance. Based on these understandings and analyses of interface characteristics and issues, this work presents a brief review on modification of interface, covering composite cathode, composite electrolyte, interface engineering, and interface layer．Some approaches of improving interface wettability and future research directions of ASSLB are given as well, which endeavor to realize the practical applications of ASSLB.

Polymers, as substrate of composite material on the surface of spacecraft, have such advantages as light mass and high strength. Atomic oxygen (AO) is one of the highest content particles of low earth orbit, and high-energy high-flux AO bombardment causes the polymers’ surface erosion and mass loss at different degree, resulting in polymers degradation. Thus, AO is one of major threats in space environment that reduces reliability of space devices and shortens their working life span. This review summarized current global protection technologies from AO in recent years. Among them, surface chemical modification method with advantages of body-modification and protection coating, providing organic/inorganic composite with modified layer through comprehensive protection performance. This review discussed the method to explore the AO protection reaction mechanism by computational simulation. Computational simulation combined with experiments may reveal nature of the protection, facilitate future researches on AO protection, and provide guidance for fabrication surface polymer materials used in domestic parts of the aerospace craft, especially the large-scale flexible space solar cell array

Visible laser has been widely used in data storage, optical communication, laser display, laser medical treatment, laser printing, and scientific research. With the development of commercial blue light LD, the direct pumping of rare-earth ions doped laser crystals have attracted a lot of interests. Currently, visible ions mainly concentrat on Pr 3+, Dy 3+, Tb 3+, and Sm 3+. Trivalent praseodymium (Pr 3+) is a famous rare-earth ion with extensive laser transitions in visible region such as blue, green, red and orange light. However, there is still a region in yellow emission which is not covered by Pr 3+. Dy 3+ and Tb 3+ have attracted much attention because of their yellow laser transitions. In addition, Sm 3+ and Eu 3+ are also typical visible rare-earth ions. In this paper, we mainly reviewed properties of rare-earth ions doped laser crystals for visible lasers, especially Pr 3+, Dy 3+, Tb 3+ and Sm 3+-doped YAlO3 (YAP), SrAl12O19 (SRA) crystals. A design criterion for Pr 3+ doped oxide materials was summarized. The crystal growth, structure, thermal properties, polarization spectroscopic and laser characteristics were analyzed in detail.

Silicon has the highest theoretical lithium insertion specific capacity, more than ten times the theoretical specific capacity of graphite electrode material, and low delithiation potential, with abundant resources and good rate characteristics, high-energy-density lithium-ion battery silicon-based materials have become hot spots in application fields such as electric vehicles and renewable energy storage systems. However, it will cause powdering and structural collapse of the silicon electrode material due to its large volume expansion effect in the process of delithiation and lithium insertion. In addition, the solid electrolyte interface (SEI) layer on the surface of silicon is repeatedly formed in the electrolyte, which increases the polarization and reduces the coulomb efficiency, eventually leading to deterioration of electrochemical performance. In order to solve the above problems and realize the commercial application of silicon electrodes. This paper systematically summarizes the work to solve the volume effect in charge and discharge process through the selection and structural design of silicon-based materials, and deeply analyzes and discusses the preparation methods, electrochemical properties and corresponding mechanisms of representative silicon-based composite materials, focusing on silicon-carbon composites and SiOx (0x≤2) based anode materials. Finally, the problems of silicon-based anode materials are analyzed and their prospects are prospected.