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.

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.

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, 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.

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.

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.

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.

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.

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%.

Cathode material LiCoPO₄ was synthesized by solvothermal method with a variety of water/alcohol solvent mixtures, including ethanol (ET), ethylene glycol (EG), and diethylene glycol (DEG). Focus of this work was set on the effect of the different alcohol solvent on morphology and particle size of material. Composition, crystal structure, morphology and particle size of the as-prepared samples were characterized by X-ray-diffraction, scanning electron microscopy and specific surface area test. The results show that relationship of the average particle size of the LiCoPO₄ samples synthesized with different alcohols solvents is in agreement with solubility of solvent for the precursor, but is inconsistent with the viscosity of solvent. Furthermore, LiCoPO₄ sample synthesized with EG/H₂O possesses the smallest particle size, great crystallinity and excellent cycle performance. Its initial discharge specific capacities reaches to 130 mAh/g at 0.05C, and it shows a capacity retention of the initial value of 88% in 20th cycle. A variety of shapes are obtained from various co-solvents: hexagonal platelets for LiCoPO₄ obtained from EG, whereas, square platelets for LiCoPO₄ from ET/H₂O and DEG/H₂O.

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.

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.

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.

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.

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.

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.

Sliding friction-wear properties of pressurelessly solid-state-sintered silicon carbide ceramics (SSiC) and liquid-phase-sintered SiC ceramics (LPSiC) pairing with tungsten carbide (WC) were researched under the frictions with or without lubrication. Under dry friction, as compared to LPSiC/WC pairs, SSiC/WC pairs have higher friction coefficient (μ) and less mass loss (Δm) due to SSiC ceramics have larger particle size and higher hardness. The surface topography of worn area was detected by SEM companying with elements mapping and micro-area XRD technology. The micro plough cut and micro fracture led to the wear of SiC ceramics. Its fatigue damage led to the wear of WC materials. The grinding-out WC grains were oxidized to amorphous WO₃ phase due to the friction heat generated in the friction. Under the wet friction with water as lubrication, as compared to SSiC/WC pairs, LPSiC/WC pairs have higher friction coefficient and less mass losses. Whether under dry friction or wet friction, the pairs with SiC ceramics as the fixed materials have lower μ and Δm than those with SiC ceramics as the rotated materials.

Flexible Bi_0.5Sb_1.5Te₃/epoxy composite thermoelectric films were prepared on polyimide substrates by screen printing. Its electrical transport properties are enhanced by optimizing the content of Bi_0.5Sb_1.5Te₃ powder. The highest power factor of the optimized Bi_0.5Sb_1.5Te₃/epoxy films reached 1.12 mW·m ^-1·K ^-2at 300 K, increased by 33% as compared with previous value. The anti-bending test results show that resistance of the thick films remains unchanged when the bending radius is over 20 mm and slightly increases within 3000 bending cycles when the bending radius is 20 mm, implying that the as-prepared films have potential application in flexible TE devices. The flexible thermoelectric leg could establish a temperature difference from 4.2 ℃ to 7.8 ℃ under working current from 0.01 A to 0.05 A, showing potential application in planar cooling field.

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.

The urban island effect and energy crisis can be relieved usefully by environmentally benign and high near-infrared reflective pigments, which is of great significance to develop of green energy-saving industry. Ions doping is an effective way to achieve the color diversity of high near infrared reflective pigments. In this work, a series of high near-infrared reflection Ba_1-xCu_xZr_1-yTb_yO₃ (x=0.15, 0.25, 0.35; y=0, 0.15) inorganic pigment co-doped with Cu ²⁺and rare earth Tb ³⁺was prepared by a Sol-Gel process. Its phase structure, ultraviolet/visible/near-infrared reflectance, and color parameters of the synthesized pigment samples were investigated and characterized by X-ray diffraction (XRD), UV/Vis/NIR spectroscopy, and color CIE-L ^*a ^*b ^* 1976 color scales. The results demonstrate that all synthesized pigments have cubic perovskite structure after calcined at 1100 ℃. The co-doping of Cu ²⁺ and Tb ³⁺ is successfully introduced into the BaZrO₃ lattice, and the color increasingly changes from white to gray, and to yellow with the increase of Cu ²⁺and Tb ³⁺concentration. Meanwhile, the obtained pigments possess high near-infrared solar reflectance in the range of 780-2500 nm, the average reflectance is up to 80%. Therefore, these Ba_1-xCu_xZr_1-yTb_yO₃ cool powdered pigment have great application prospect in the building coatings.

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.

A new nano silver particels loaded graphene oxide (AgNPs@GO) was obtained through ultrasonic assisted liquid phase method. In AgNPs@GO, nano silver particels (AgNPs) are mainly anchored at oxygen containing groups and defects of graphene oxide (GO) sheets, part of GO sheets are reduced and some Ag(0) atoms have been oxidized to Ag ⁺ ions. AgNPs@GO exhibits significantly stronger ability for inhibiting Pseudomonas aeruginosa than that of AgNPs and GO. Therefore, AgNPs@GO was further introduced to polyethylene (PE) matrix as an additive to prepare a new composite material 0.48wt%-AgNPs@GO/PE. Compare with bare PE and AgNPs doped PE composites, 0.48wt%-AgNPs@GO/PE not only has a better antibacterial ability and stronger water vapor barrier property, but also dissolves out less nonvolatile substance than PE in water and ethanol solution.

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.

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.

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.

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 ℃.

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.

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.

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.

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

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.

In this work, Mo, Y, Al, and C were used as raw materials to synthesize a novel (Mo_2/3Y_1/3)₂AlC MAX phase by spark plasma sintering (SPS) at 1550 ℃, and the corresponding accordion-like MXene was successfully obtained with a milder chemical etching method. The chemical composition and microstructure of the materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive spectrometer (DES). The final product was Mo_1.33CT₂ MXene with functional groups on the surface. At the same time, the electronic structure and electronic properties of the novel (Mo_2/3Y_1/3)₂AlC MAX phase and the corresponding Mo_1.33CT₂ MXene were studied by the first-principles density functional theory. The calculated results show that all of them exhibit metallic properties, which are expected to be applied for energy storage, biosensors and electrocatalysis.

By using hydrothermal and spin-coating method, Ti mesh supported composite structure, TiO₂ nanowire arrays/Yb-Er-F doped TiO₂ upconversion luminescence nanoparticles (TNWAs/YEF-TiO₂-UCNPs), was synthesized and assembled into flexible dye-sensitized solar cell (DSSC). The effect of YEF-TiO₂-UCNPs optical property on the power conversion efficiency (PCE) of this device was studied. In addition, the influence of NbCl₅ solution coating on morphology and performance of flexible DSSC was also investigated in detail. It is shown that the YEF-TiO₂- UCNPs could expand the range of incident light utilization, in the meantime, however, increase the electron recombination in photoanode. Nb₂O₅ coating layer served as an energy barrier at the semiconductor/electrolyte interface, increased the composite resistance R_rec to inhibit electron recombination, improved the electron collection efficiency η_ec and photogenerated electron lifetime τ_e, then elevated the short circuit current and the open circuit voltage, finally enhanced the performance of DSSC. The Nb₂O₅@TNWAs/YEF-TiO₂-UCNPs composite structured DSSC achieved the best PCE of 6.89% with 20 mmol/L NbCl₅ ethanol solution coating, increased 24.3% compared with the uncoated blank device.

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.