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.

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 M_n+1X_n 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 M_n+1X_nT_x (T_x 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.

Inspired by the lotus leaves in nature against contaminants in the muddy environment, superhydrophobic phenomena has attracted tremendous attentions among the research communities, and triggered the researchers to fabricate an artificial superhydrophobic surface for real-time applications. In this paper, the development of bioinspired materials is combed in accordance with time evolution. Besides, the advantages/disadvantages of numerous preparations in superhydrophobic coating are discussed through the recent researches. In addition, the recent advances of superhydrophobic applications are summarized, such as self-cleaning behavior, anti-icing properties, anti-corrosion performance and oil/water separation. Particularly, this review introduces the mechanism and implementation of anti-icing properties by superhydrophobic coating. As for superhydrophobic coating, current challenges are pointed out and its future development for applications is prospected. Overall, this review provides a reference for research and development of superhydrophobic coatings.

A novel kind of electrocatalytic oxygen evolution catalyst was fabricated by introducing g-C₃N₄ ultrathin films onto the surface of attapulgite (ATP) via a simple in-situ depositing technique, combined with freeze-drying and programmed roasting process. The obtained product was identified as ATP/g-C₃N₄. In order to achieve the best catalyst, a series of ATP/g-C₃N₄ composites with different mass fraction of ATP were obtained and marked as ATP/g-C₃N₄-w, where w represents the mass fraction of ATP (w =mATP: (mATP + mg-C₃N₄)= 0.33, 0.40, 0.50, 0.67). Results show that g-C₃N₄ thin layers are uniformly loaded onto the ATP surface via the chemical bond (Si-O-C), which is beneficial to tailor the surface electronic structure of g-C₃N₄ and provide more active sites. Their electrocatalytic oxygen evolution properties in 0.1 mol/L KOH were investigated. It is found that ATP/g-C₃N₄-0.50 presents the best oxygen evolution catalytic performance and has excellent oxygen evolution stability. Its oxygen evolution over potential is 410 mV and the Tafel slope is 118 mV/dec at a current density of 10 mA/cm ². The results suggest that ATP/ g-C₃N₄-0.50 can be used as a potential oxygen evolution catalyst.

In recent years, hexagonal boron nitride (h-BN) two-dimensional (2D) atomic crystal has attracted considerable attention due to its unique structure, novel property and potential applications. The synthesis of high quality h-BN determines how far we can go for property research and practical applications. However, the sizes of h-BN domains obtained by mechanical exfoliation were limited to several micrometers. Transition metal substrates are usually used in the CVD growth of 2D h-BN layers, and thus a transfer process is required for fabricating h-BN-based electronic devices. Therefore, it is strongly desirable to directly synthesize 2D h-BN on dielectric substrates. In this article, we review recent process on the direct growth of h-BN by CVD, MOVPE, PVD on different dielectric substrates, including silicon-based substrates, sapphire, quartz, etc. Several approaches, such as, increasing substrate temperature, oxide-assisted nucleation, and surface nitridation were adopted to directly grow h-BN on dielectric substrates. Besides, we also summarized the main applications of 2D h-BN grown on dielectric substrates.

Silver nanowire transparent conductive film is one of the new indium-free electrode materials. It has attracted increasing attention from academia and industry due to its superior optoelectronic properties and excellent flexibility. It has been employed in a wide variety of applications in displays, touch panels, solar cells, smart heaters, electromagnetic interference shielding, and so on. However, silver nanowire transparent conductive film has a serious stability issue in service, for example, break or spheroidization above 300 ℃ under fulfidation, accelerating the degradation under ultraviolet light, pores for mation or even breakdown due to electromigration. In this review, the degradation phenomena is thoroughly introduced, the degradation mechanisms is analyzed, and the remedy strategy of degradation is discussed.

Due to its unique physical and chemical property, diamond is widely used in many fields such as detectors and optoelectronic devices. Many scholars’ attention is drew into single crystal diamond because of its potential to significantly increase the functionality of these devices. Presently, single crystal diamonds grown heteroepitaxially on iridium (Ir) substrates reach the largest size and an excellent growth quality. In this paper, substrates with different structures for nucleation and growth processes of epitaxial diamond are introduced. The mechanisms of diamond nucleation by Bias Enhanced Nucleation (BEN) method and growth undergoing an Epitaxial Lateral Overgrowth (ELO) process are described, including technique of Patterned Nucleation and Growth(PNG). Limitations of current study are pointed out, and the future development of heteroepitaxial theory and experiment are also forecasted in this paper.

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.

Two-dimensional MXene nanosheets with vertical junction structure was employed for easy immobilization of horse radish peroxidase enzymes to fabricate the electrochemical hydrogen peroxide (H₂O₂) biosensor. The synthesized MXene nanosheets exhibited large specific area, excellent electronic conductivity and good dispersion in aqueous phase. Horse Radish Peroxidase (HRP) enzymes molecules immobilized on MXene/chitosan/GCE electrode demonstrated good electrocatalytic activity toward reduction of H₂O₂. The fabricated HRP@MXene/chitosan/GCE biosensor exhibited a wide linear range from 5 to 1650 μmol?L ^-1, a limit of detection of 0.74 μmol?L ^-1 and good operation stability. The fabricated biosensor was successfully employed for detection of trace level of H₂O₂ in both solid and liquid food.

As a new solid-state lighting source, the white light-emitting diodes (WLEDs) have a greatly promising application in the field of lighting and display. They have superior advantages of high luminous efficacy, fast response speed and long service life, etc. compared with the existing light sources (incandescent lamps, fluorescent lamps, etc.). At present the WLEDs are commonly fabricated by combination of a blue LED chip and YAG: Ce ³⁺ yellow-emitting phosphor, and combination of a ultraviolet-near ultraviolet excitation chip and red-green-blue (RGB) emitting color phosphors, compared with the above two phosphors, the single-phase phosphors containing white emission have the advantages of a higher luminous efficacy, color rendering. Meanwhile, the single-phase phosphors may effectively solve the reabsorption problem existing in RGB phosphors. There have been a large number of reports on the research of single-phase phosphors, involving a variety of material systems. According to the principle of luminescence, it can be simply divided into three groups: single ion doped system, multi-ion doped system and other systems which do not rely on rare earth ion to light. This paper reviews the research progress of single-matrix WLEDs phosphors, and points out the problems in their development, and forecasts the future development trend.

Sapphire rod with micro-tube (inner diameter: 470 μm) and sapphire plate with micro-tube (inner diameter: 160 μm) were grown by the edge-defined-film fed method (EFG). Profile curves of the small liquid menisci were investigated on the base of numerical solution of the Young-Laplace equation. By inserting Mo wires, new type of die was designed to form and sustain size of micro-tube in the volume of the crystal. Two problems were solved at the same time: 1) obtaining high quality sapphire crystal; 2) forming and sustaining necessary micro-tube sizes in the volume of the crystal. The crystal were transparent, colorless, no cracking and good XRC value of 3.8 arcmin, demonstrating the high quality of the as-grown crystal.

The structure and electrical properties of Ce ³⁺-doped intergrowth bismuth layer-structured piezoelectric ceramics Na_0.5Bi_8.5-xCe_xTi₇O₂₇ (NBT-BIT-xCe, 0≤x≤0.1) prepared by conventional solid-state reaction process were systematically studied. In this study, all the ceramic samples were found to possess a single bismuth layer structure, and with the increase of x content, there is an increasing trend towards the lattice distortion of the sample, while the average grain size decreased. As demonstrated by dielectric spectrum and DSC method, two dielectric anomalies of the samples occur, which corresponds to ferroelectric phase transitions of the ceramics. And Ce ³⁺doping significantly reduces concentration of oxygen vacancy and dielectric loss in materials, improving piezoelectric constant (d₃₃) of ceramic samples. The resultant ceramics with x=0.06 reached the optimal performance, possessing a d₃₃ up to 27.5 pC/N with the Curie temperature of 658.2 ℃ and tanδ=0.39%.

The nitrogen-doped porous carbon applied for oxygen reduction reaction (ORR) has aroused extensive interests due to its unique physical and chemical properties. However, the complicated nitrogen-doping strategy and high cost limit its extensive application. In this work, a series of nitrogen-doped porous carbons were prepared by a facile pyrolysis process coupling with subsequent KOH activation using renewable N-enriched biomass potato as carbon source. Effects of activation temperature and KOH amounts on the textural properties and electrocatalytic ORR activities of the final samples were investigated in detail. The KOH activation treatment results in a high specific surface area (SSA) and hierarchical porous structure, which is beneficial for improved ORR performance. The optimized NPC-750 possesses a high SSA of 1134.2 m ²?g ^-1, developed hierarchical pores as well as moderate nitrogen content (1.57at%). It also exhibits a positive onset potential of 0.89 V (vs. RHE) and half-wave potential of 0.79 V (vs. RHE). Simultaneously, the advanced long-time stability and methanol-tolerance capacity were also obtained, implying that these biomass-derived porous carbons are potential low-cost ORR electrocatalysts. Moreover, these porous carbons show great potential in various fields including supercapacitors, adsorption/separation, catalysis and batteries as well.

Binders have a great impact on the performance of lithium-ion batteries, although small doses of binder is applied. The traditional binder poly (vinylidene fluoride) cannot meet the requirements of modern lithium-ion batteries, especially those with high specific capacity, because it interacts with electrode materials through weak Van de Waals force. The surfaces of most electrode materials have polar groups which can strongly interact with polar polymeric binders. Therefore, the polar polymeric binders have been paid much attention, recently. Many factors of polar polymeric binders influence the properties of lithium-ion batteries. This review mainly focuses on the impacts of structure properties of polar polymeric binders on lithium-ion batteries, including structural feature, adhesiveness, mechanical properties, conductivity, and other properties Besides, we propose the strategies of designing next-generation binders for lithium-ion batteries from molecular level, and claim the future direction and prospects of the binders.

Bio-oil obtained from biomass can be used as an important raw material for hydrogen production. In this work, acetic acid (HAc) from bio-oil was selected as the model compound to produce hydrogen via auto-thermal reforming (ATR). Fe-promoted Co-based hydrotalcite-like Co_xAl₃Fe_yO_m±δ catalysts were prepared by co-precipitation method and characterized by XRD, N₂ physisorption, H₂-TPR and TG to study the relationship between the catalytic performance and structure within these catalysts. The characterization results show that hydrotalcite-like structure of (Co/Fe)_xAl₂CO₃(OH)_y·zH₂O were obtained by co-precipitation, then transformed to alumina supported spinel structures, including CoAl₂O₄, Co₃O₄, Fe₃O₄, and FeAl₂O₄, after calcination. BJH analysis indicated that within these calcined Co_xAl₃Fe_yO_m±δ catalysts, there were mesoporous structures, in which the Co_0.45Al₃Fe_0.4O_5.55±δ centered structure with pore size distribution 4 nm. As suggested by H₂-TPR and XRD, the reducibility of Co metal was enhanced with the Fe promoter, and there were CoFe alloys formed after reduction. In the stability test, the hydrogen yield reached 2.72 mol-H₂/mol-HAc and remained stable, meanwhile, the CoFe alloy was also stable and no carbon deposit was detected after reaction, indicating that there was high resistance to oxidation and coking within Fe-promoted Co_xAl₃Fe_yO_m±δ catalysts.

In this study, high-strength silicon carbide (SiC) matrix composites reinforced by short carbon fiber (C_sf) (SiC/C_sf) were fabricated by slip casting and reaction sintering. The effects of the dispersant (tetramethylammonium hydroxide, TMAH) content and mixing time on the viscosity of the slurry were investigated. In addition, the influences of the volume fraction of C_sf and particle size of SiC powder on the mechanical property were also studied. It is found that the viscosity of slurry with 0.1wt% TMAH is the lowest and the mixing time is preferably controlled at 6 h. The composites with 35vol% C_sf shows the highest flexural strength of (412±47) MPa. The composites with 5 μm SiC powder achieves the highest flexural strength of (387±40) MPa. Grain composition demonstrates that the sample prepared by a mixture of 5 and 50 μm SiC powder at a ratio of 2 to 1 shows relatively excellent mechanical properties with the flexural strength up to (357±41) MPa.

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.

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.

MXenes—two-dimensional (2D) compounds generated from layered bulk materials, have attracted significant attention in energy storage fields. However, low mass loading of MXenes results in low areal capacity and impedes the practical use of MXenes electrodes. Inspired by natural basswood, an ideal architecture with natural, three-dimensionally (3D) aligned open microchannels was developed for high Ti₃C₂T_x mass loading. Compared with reported Ti₃C₂T_x electrode structure, the 3D porous carbon matrix has several advantages including low tortuosity, high conductivity and good structure stability. The Ti₃C₂T_x assembled with the wood carbon can deliver a high areal capacity of 1983 mF/cm ² at 2 mV/s with a high Ti₃C₂T_x mass loading of 17.9 mg/cm ² when used as electrode for supercapacitors. This work provides a new strategy to develop 3D porous electrodes for MXenes, which can achieve high areal capacity.

To reveal influence of doping ions on the magnetic properties of strontium ferrite materials with magnetoplumbite configurations, we studied the stable configurations and magnetic structures of strontium ferrite with and without manganese doping. The results show that the strontium ferrite is ferrimagnetic, which is consistent with the previous reports. Comparing the GGA and GGA+U approaches, the U value exhibits a significant impact on the electronic structures and atomic magnetic moments. When 3.7 eV is adopted for U value, the system changed from a metal to a semiconductor with a spin up band gap of 1.71 eV. The total magnetic moment of the pure strontium ferrite is 40 μ_B. For the SrFe_12-xMn_xO₁₉ system, the site preference of Mn substituting Fe is investigated with x=0.5 and x=1.0. When x = 0.5, the single doping Mn atom preferentially occupies the Fe (12k) site. For x=1.0, the two Mn atoms preferentially occupy the Fe (12k) and Fe (2a) sites, respectively. Doping Mn has little impact on the lattice structure of strontium ferrite, but have a significant effect on the total magnetic moments and electronic structures. When x=0.5 and x=1.0, the band gap values for spin up electrons reduced to 0.85 and 0.49 eV, and the total magnetic moments reduced to 39 and 38 μ_B, respectively. This study may provide a theoretical foundation for future experimental studies.

Despite excellent catalytic capability, Cu₂O nanomaterial exhibits weak stability which limits its application. In this study, a novel kind of Cu₂O, Cu₂O/BNNSs-OH, supported catalyst with highly catalytic efficiency and stability, was facilely fabricated via a controllable liquid phase reduction of ascorbic acid and combining with an annealing process. Cu₂O/BNNSs-OH catalyst was synthesized by using boron nitride nanosheets (BNNSs), prepared by the “push-pull” effect of polyvinylpyrrolidone (PVP) and water phase change, as a supporter and spherical Cu₂O nanoparticles (2-7 nm) prepared by forward titration (ascorbic acid→Cu ²⁺, solution with a pH 11) as active components. Morphology and structure of as-obtained samples were characterized by scanning electron microscopy (SEM), high resolution transmission electronic microscopy (HRTEM), atomic force microscopy (AFM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The results of the synthetic method showed that spherical Cu₂O nanoparticles were uniformly dispersed on the carrier surface and BNNSs displayed some stabilization effect on Cu₂O which could be prevented from being oxidized into CuO. Moreover, the catalytic activity was investigated by catalytic reduction reaction of 4-nitrophenol to 4-aminophenol. Cu₂O/BNNSs-OH with high catalytic activity similar to the noble metal catalyst for the reduction of 4-nitrophenol is highly reusable for five successive cycles without significant degradation and activity loss.

This study presents a triboelectric nanogenerator (TENG) with graphene forest as electrode. Graphene forest was fabricated by plasma enhanced chemical vapor deposition (PECVD) process, which shows great different morphology compared with other ‘wall-like’ vertically oriented graphene so far. Graphene forest films are composed of graphene nanoflakes, exhibiting not only low sheet resistance ((110±5) Ω/□) but also uniquely discrete ‘tree-like’ morphology, which are favorable to contact and friction with other materials. According to its morphology superiority, Kapton film and graphene forest film were utilized as electrodes for triboelectric nanogenerator, in which an open circuit voltage of 20 V and a short circuit current of 0.75 μA are obtained. Furthermore, the working principle of the graphene forest based triboelectric nanogenerator was discussed. At last, three LEDs of different color in demo circuit were lighted up by as-prepared nanogenerator, which proves the effective application of graphene forest in triboelectric nanogenerator.

To overcome the limitation of narrow photo-absorption range and high electron-hole recombination rate of pure BiOCl, a nanocomposite of carbon quantum dots (CQDs) and BiOCl with highly efficient photocatalytic activity was fabricated. The photocatalytic decomposition of rhodamine B (RhB) showed that the CQDs/BiOCl nanocomposite displayed superior photocatalytic performance to pure BiOCl, which was about 3.4 times higher than that of the latter. The optimal loading amount of CQDs was 7.1wt%, which could completely decolorize RhB within a short period of only 2 min, while the degradation rate of RhB was only 29.5% by pure BiOCl in the same period. UV-Vis diffuse reflectance spectra (UV-Vis DRS), photoelectrochemical measurement, and radicals trapping experiments were performed to elucidate the possible mechanism for the enhanced photocatalytic activity of the CQDs/BiOCl composite. The results show that CQD can expand the visible light absorption range of BiOCl, which is beneficial for light harvesting and generation of electron-hole pairs. Moreover, CQDs has unique up-converted photoluminescence behavior, as well as photo-induced electron transfer ability, which leads to enhanced photocatalytic performance of the CQDs/BiOCl composite.

MoSe₂ was deposited by electrochemical reduction method on TiO₂ nanotube arrays which were prepared by anodic oxidation in ethylene glycol electrolyte, in which sodium molybdate and seleninic acid were used as raw materials. The composites were characterized by X-ray diffraction and scanning electron microscope, and I-V plot and electrochemical impedance spectroscopy were measured by electrochemical workstation. The results show that a p-n heterojunction is formed between molybdenum diselenide and titanium dioxide, which can reduce the combination of photo-generated electron-hole pairs and charge transfer resistance, and can increase its carrier concentration and light response current density. The composite deposited at -0.5 V in the electrolyte containg 2 mmol/L seleninic acid for 30 s exhibits optimum photo-electrochemical performance after 300 ℃ heat treatment, with a high photocurrent density of 1.17 mA/cm ² without bias, which is approximately three times higher than that of blank sample. And the charge transfer resistance decreased from 331.6 Ω/cm ² to 283.9 Ω/cm ². Selenide molybdenum agglomerates seriously to block the TiO₂ nanotube once heat treatment over 330 ℃, resulting in a lower performance.

The electrocaloric (EC) effect is strongly related to interaction of polarization and temperature changes, showing great potential in high-efficient solid state refrigeration. This work focuses on the Pb_0.3Ca_xSr_0.7-xTiO₃ (PCST(x), x = 0.00, 0.05, 0.10, 0.15) ceramics in which the influence of Ca content on dielectric and ferroelectric property under electric field was studied, and the EC temperature change was calculated through indirect method. Substitution of Ca largely modifies the diffused phase transition behaviors of PCST ceramics, which the diffusion exponent of PCST(0.05) increases with electric field up, indicating a promising wide temperature range of large electrocaloric effect. Thus, the largest adiabatic temperature change (1.71 K) is obtained near the room temperature in PCST(0.05) by indirect method. With an electric field of 8 kV/mm, PCST(0.05) ceramic shows good EC effect in a wide temperature range that the adiabatic temperature change is larger than 1 K from 5 ℃ to 70 ℃.

Due to the fact that the conventional bioceramic microspheres lack target function, novel litchi-like porous microspheres composed of a core of CaCO₃ and a tunable magnetic-hydroxyapatite (HA) shell were successfully prepared in this study. Antitumor drug, doxorubicin (DOX), was effectively loaded on the HA microspheres which possess magnetic targeting function. In addition, the HA shell, which had favorable biocompatibility and pH response characteristics, could be used to control release of loaded DOX from the litchi-like superparamagnetic microspheres in a simulated acidic tumor cell environment, effectively killing tumor cells and reducing toxic side effects to normal cells. The smart design presented in this study, which incorporates a tunable superparamagnetic shell and a controlled architecture, allows the sensitive release of drugs for efficient antitumor activity.

Heterojunction-type nanostructures based on ZnO nanomaterials are one of the important candidates for constructing high-performance ultraviolet (UV) photodetectors. In this work, a novel ZnO nanorods/ZnCo₂O₄ nanoplates heterojunction was designed and prepared, and the electrical properties and photodetection properties of the as-prepared heterojunction were investigated. ZnCo₂O₄ nanoplates were constructed into uniform thin film on ITO glass substrate using oil/water interface self-assembly. Next, ZnO nanorod arrays with uniform orientation and proper density were grown on ZnCo₂O₄ nanoplates thin film using hydrothermal method with the help from ZnO seed layer. As a result, high-quality ZnO nanorods/ZnCo₂O₄ nanoplates heterojunction was achieved. This heterojunction has a high rectification ratio of 673.7. Under reverse bias, this heterojunction has a light-dark current ration of more than two orders of magnitude. The UV-visible rejection ratio of this heterojunction is 29.4, which indicates its selective detection of UV light. These results effectively prove the potential of this ZnO nanorods/ZnCo₂O₄ nanoplates heterojunction in constructing high-performance UV photodetectors.

Thermal diffusivity can be measured by the laser flash method. Previous study showed that Cu₂S has extremely low thermal diffusivity during the first-order phase transition. However, when laser is applied on the measured sample, both the absorption/emission of light and the increase of temperature on the measured sample will occur. Their effects on the measurement accuracy of the thermal diffusivity during the phase transition have not been investigated yet. In this study, it is found that the absorption/emission of light has neglectable influence on the thermal diffusivity measurement of Cu₂S. However, the increase of temperature can significantly influence the measurement results and shift the temperature when the thermal diffusivity of Cu₂S starts to decrease below the starting temperature of the phase transition determined by DSC. This can be solved by building a Cu₂S/graphite double-layer structure via using the graphite to absorb part of the laser’s energy. Furthermore, a thermal transport model is developed to extract the real thermal diffusivity from the measured thermal diffusivity of the Cu₂S/graphite double-layer structure. This work is meaningful for accurate characterization and understanding of the thermal diffusivity of phase transition materials, photosensitive materials, and heat sensitive materials.

Low energy/power density and inferior cycling stability are bottlenecks to restrict the applications of sodium-ion batteries. Recently, coating the surface of cathode material by metal oxides containing oxygen vacancies, was regarded as an effective strategy to improve electrical conductivity and power/energy density. In this study, Na₃V₂(PO₄)₂F₃@V₂O_5-x nanosheets were synthesized via hydrothermal strategy followed by heat treatment. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis were applied to investigate the structure of Na₃V₂(PO₄)₂F₃@V₂O_5-x. As a cathode of sodium- ion batteries, Na₃V₂(PO₄)₂F₃@V₂O_5-x delivers excellent cycling stability and rate capability. It exhibits an initial discharge capacity of 123 mAh?g ^-1 at 0.2C, and a discharge capacity of 109 mAh?g ^-1 after 140 cycles. At 1C, its initial reversible capacity is 72 mAh?g ^-1, which remains 84% after 500 cycles. The outstanding electrochemical property could be ascribed to its enhanced sodium-diffusion and improved electronic conductivity induced by disordered surface coating. Furthermore, it encourages more investigations into practical sodium-ion battery applications.

MoS₂ quantum dots (QDs) decorated NH₂-MIL-125 (MoS₂ QDs/NH₂-MIL-125) heterostructures were successfully fabricated by a facile method. XRD results exhibit that NH₂-MIL-125 and MoS₂ form crystals in the synthesis process of MoS₂ QDs/NH₂-MIL-125 heterojunctions. TEM results demonstrated clearly that the MoS₂ Quantum dots with size of about 4 nm successfully disperse on the surface of NH₂-MIL-125 plate. Compared with bulk MoS₂ and NH₂-MIL-125, the MoS₂ QDs/NH₂-MIL-125 heterostructures exhibit enhanced photocatalytic performance in degradation of methyl orange under visible light irradiation, about 5.8 and 7.4 times higher that of pure bulk MoS₂ and NH₂-MIL-125, respectively. Meanwhile, MoS₂ QDs/NH₂-MIL-125 composites exhibit good stability and reusability during cycle experiment. The excellent photocatalytic activity of MoS₂ QDs/NH₂-MIL-125 heterostructures is attributed to the formation of heterojunctions between MoS₂ QDs and NH₂-MIL-125, Tacilitating separation of the photogenerated charge carries. PL results prove that MoS₂ QDs/NH₂-MIL-125 composites own lower recombination of photogenerated electrons and holes, resulting in superior photocatalytic ability.

Co-doping of silicon in zinc gallate spinel persistent luminescent phosphor was adopted to enhance the afterglow properties. Firstly, a series of silicon-chromium co-doping zinc gallate spinel samples were prepared by high temperature solid state reaction method. Phosphor with chemical formula of Zn_1+xGa_2-2xSi_xO₄:Cr ³⁺ (x = 0, 0.1, 0.15, 0.2, 0.5, 1) was obtained with the raw materials of ZnO, Ga₂O₃, SiO₂, and Cr₂O₃. The experimental results show that the introduction of suitable concentration of silicon improves the afterglow performance effectively. The strongest afterglow intensity was obtained for sample with x = 0.2, which is 3 times higher than ZnGa₂O₄:Cr ³⁺, and the afterglow duration is up to 24 h. Through further trap distribution analysis, it is shown that the introduction of silicon in the ZnGa₂O₄ host can regulate the distribution of trap depths. Particularly, besides the antisite defects, the co-doping of silicon can induce the formation of aliovalent substitution defects and interstitial defects, as well as tune the band gap value, thereby achieving the purpose of improving the afterglow performance.

Cu₂S shows excellent thermoelectric properties as a material with phonon liquid-electron crystal characteristics. However, traditional preparation methods are cumbersome and difficult to afford bulk Cu₂S with uniform composition, high density and excellent thermoelectric properties. In this study, a novel method named Pulsed Electric Current Sintering was introduced to synthesize and sinter Cu₂S materials in one step consuming only 30 s. The synthesis of Cu₂S under intense pulsed electric field includes three steps. A small amount of CuS and Cu₂S forms in the first step; most of Cu₂S and part of Cu_1.96S are produced in the second step; finally, the remained Cu_1.96S and Cu react to form completely pure Cu₂S. The Cu₂S bulk obtained by this method is a dense bulk with homogeneous composition, and contained abundant multi-scale microstructures. The thermoelectric performance is optimized by regulation of Cu-deficient Cu_2-xS. The maximum ZT of Cu_1.97S bulk at 873 K is 0.72, which is 49% higher than that of the pristine sample.

Persistent organic pollutants can be effectively removed by photocatalytic oxidation, which reveals potential application prospects in the field of wastewater purification. Binary reduced graphene oxide and graphitic carbon nitride (RGO/g-C₃N₄) visible-light photocatalyst was successfully fabricated by the freeze drying assisted thermal polymerization method with urea and dicyandiamide as raw materials, respectively. The morphologies, structures and optical properties were characterized by various techniques. It was found that g-C₃N₄ and RGO nanostructures formed an intimate contact across the heterojunction interface. The photodegradation performances of catalysts were evaluated by removing bisphenol A (BPA) with the activation of persulfate (PS). The results indicated that the photocatalytic activities of photocatalysts were enhanced with the addition of PS as an oxidant and electron acceptor under visible light irradiation (λ>420 nm). Moreover, BPA was almost completely removed by RGO/g-C₃N₄ prepared with urea as raw material in 40 min. After five recovery tests, the removal efficiency of BPA for the catalyst was up to 80% within 40 min under visible light irradiation, which exhibited superior stability.

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.

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.

ZrB₂-SiC ceramics present better oxidation resistance and mechanical properties than monolithic ZrB₂ ceramics. However, the small damage tolerance and poor crack growth resistance, which result in the low fracture toughness, limit the engineering application of ZrB₂-SiC ceramics. Focusing on this issue, microstructure design and introduction of toughening phase are two effective approaches to improve the fracture toughness of ZrB₂-SiC ceramics. In this work, ZrB₂-SiC and C_f/ZrB₂-SiC composites were toughened respectively by interlocking microstructure and chopped carbon fibers via reactive hot pressing. For the ZrB₂-SiC composites, the interlocking microstructure formed by in-situ ZrB₂ platelets presented excellent self-enhancing effect. The ZrB₂-SiC composites had high bending strength and fracture toughness. However, the composite exhibited typical brittle fracture characteristics. Compared with ZrB₂-SiC composite, the flexural strength of C_f/ZrB₂-SiC composite decreased, but the fracture toughness was comparable with the ZrB₂-SiC composite. Furthermore, the critical crack size and the work of fracture of C_f/ZrB₂-SiC composites significantly improved, and the composite presented the non-catastrophic failure mode.

The inorganic filler is the main component of the dental restoration composite resin, which is very important for the properties and functions of composite resin. In this paper, zinc oxide (ZnO) mesocrystal microspheres were prepared from Zn(NO₃)?6H₂O solution in presence of triethanolamine as the soft template by hydrothermal method, these microspheres were self-assembled by 37.5 nm ZnO crystallite and with good order. ZnO mesocrystal microspheres were modified with γ-methacryloxypropyl trimethoxysilane (γ-MPS) and subsequently mixed with modified SiO₂ microspheres as fillers, and then added to the Bis-GMA/TEGDMA system to prepare the composite resin. Through morphology observation and performance test, it is found the filler is uniformly dispersed in composite resin. The one filled with 20wt% ZnO mesocrystals has excellent mechanical properties and wear resistance, among which the flexural strength and modulus reach 133 MPa and 9.8 GPa, respectively with the volume loss at 1.02 mm ³ after 3000 times of wearing, which was 88.7% and 90.8% lower than that of the composite resin filled with commercial ZnO microspheres and bare SiO₂, respectively. Moreover, the antibacterial rate of zinc oxide composite resin against streptococcus mutans in the oral cavity reached 99.9%.

Recently, a new type of 2D transition metal carbides or nitrides (MXene) has attracted wide attention due to its large specific surface area, good hydrophilicity, metallic conductivity and other physical and chemical properties. 2D Ti₃C₂T_x MXene was obtained by etching Al layer of Ti₃AlC₂ with LiF and HCl and then mechanically delaminated. And the monolayer Ti₃C₂T_x nanosheets with lateral dimension of 625 and 2562 nm can be prepared by changing the intensity and way of mechanically delamination, as well as the centrifugation rate and time. Then their morphology, structure, composition, and electrochemical performance of Ti₃C₂T_x were studied. The results showed that the specific capacitance of Ti₃C₂T_x with smaller lateral size (<1 μm) can reach 561.9 F/g, higher than that of reported graphene, carbon tube and MnO₂ in the repotted literatures. And the Ti₃C₂T_x electrode still remained 96% of the initial specific capacitance after 10 ⁴ testing cycles.

Extrusion stress due to phase change of the NiS, internal stress due to CTE mismatch between the NiS and glass, and local concentrated stress around the NiS due to synergistic effects above were quantitatively calculated based on equal strength theory and the deformation coordination relation between NiS and glass in this work. The effects of NiS particle diameter, local strength of glass and ambient temperature on spontaneous breakage of tempered glass were analyzed. The critical diameter of NiS particles was determined as well. The results show that the fundamental reason for spontaneous breakage of tempered glass is the circumferential concentrated stress (tensile stress) near the NiS particle. There exists non-linear relations between circumferential stress and NiS particle diameter of which the circumferential stress decreases rapidly with the decrease of NiS particle diameter when it is less than 0.2 mm, but circumferential stress increases moderately when it is greater than 0.5 mm. The critical diameter of NiS particle which causes the spontaneous breakage of tempered glass decreases with the increase of surface stress in the tempered glass. It is difficult to induce spontaneous breakage of tempered glass when the diameter of NiS particle is less than 0.1 mm. The circumferential stress increases linearly with the increase of ambient temperature, and the stress increases slightly faster for the NiS with larger diameter.