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Aqueous metal-H2O2cells are emerging as power batteries because of their large theoretical energy densities and multiple application scenarios, especially in underwater environments. However, the peak power densities are less than 300 mW cm−2for most reported metal-H2O2cells based on Mg/Al or their alloys due to the self-corrosion. Herein, we reported a Zn-H2O2cell with ultrafine bean-pod-like ZnCo/N-doped electrocatalysts that were synthesized viamultifunctional single-cell-chain biomass. The electrocatalyst provides abundant active sites on the crinkly interface and offers a shortened pathway for electron/ion transfer due to the desired root-like carbon nanotube (CNT) arrays. Therefore, the optimized electrocatalyst exhibited outstanding oxygen reduction reaction (ORR) activity, with high E1/2(0.90 V) and Eonset(1.01 V) values. More importantly, Zn-H2O2batteries achieve a record-breaking peak-power density of 510 mW cm−2and a high specific energy density of 953 Wh kg−1.

Multimode emission of Mn2+for multimode fluorescence anticounterfeiting is achieved by cation site and interstitial occupancy in Ca2–xMgxGe7O16. The rings in Ca2–xMgxGe7O16have a significant distortion for Mn2+ions to enter the ring interstitials with a luminescence center at 665 nm, which is supported by XRD refinement results and first-principles calculations. The interstitial Mn2+ion has good thermal stability with an activation energy of 0.36 eV. Surprisingly, these two luminescence centers, the cation site Mn and the interstitial Mn, have an obvious afterglow, and the disappearing afterglow will reappear by heating or irradiating with the 980 nm laser. The afterglow is significantly enhanced, as MnO2is used as the manganese source, which is explained in detail by the thermal luminescence spectrum. Finally, Ca2–xMgxGe7O16:Mn2+fully demonstrates its excellent prospects in fluorescent anticounterfeiting, information encryption, and optical information storage.

A starch-polyacrylamide (S-PAM) double-network hydrogel characterized by high ionic conductivity, excellent water retention capacity, mechanical flexibility, and strong adhesion was prepared using a simple graft copolymerization technique. Remarkably, the flexible zinc-air battery, assembled with the high-performance S-PAM electrolyte and CoFe-NC bifunctional catalyst, exhibited a high discharge voltage of 1.3 V and sustained operation for over 40 h. Furthermore, the battery maintained a stable voltage output under various bending and impact conditions, demonstrating a great potential for wearable applications.

The practical applications of lithium-sulfur (Li-S) batteries are limited by the low conductivity of sulfur and the shuttle effect of soluble polysulfides during the charge-discharge process. At the same time, biomass-based carbon materials have been acknowledged as the cost-effective and direct settlement to mitigate or overcome these problems due to their renewability, facile processing, and pollution-free characteristics. Therefore, in this work, we report the natural nori-based CoO nanoparticles decorated hierarchical porous carbon (HPC) for high-capacity Li-S battery cathodes. The HPC with an extremely high surface area of 2089 m2g−1provides a good substrate for the accommodation of CoO nanoparticles, which can effectively seize the lithium polysulfides and facilitate their redox conversion. As a result, the CoO-HPC/S cathode exhibits a high discharge capacity of 1557.1 mA h g−1, as well as excellent rate performance and cycling stability. Due to the naturally abundant nori-based cathode materials, the resultant Li-S battery is supposed to be an attractive and sustainable energy storage device.

Calcium bismuth niobate (CBN) ceramic, as a core element of high-temperature piezoelectric sensors, has attracted widespread attention due to its high Curie temperature within the class of Aurivillius compounds. However, CBN usually faces two shortcomings: poor piezoelectric constant and low resistivity. In this work, CBN-based ceramics with donor–acceptor ions (W/Co) co-substituted at B-site were prepared by solid-state reaction method, and structure–property relationship of ceramics was studied in detail. Co-substitution of W/Co ions effectively improved the electrical property and hardness of CBN ceramics. CaBi2Nb1.91(W2/3Co1/3)0.09O9exhibits enhanced electrical and mechanical properties including high resistivity of ∼107Ω⋅cm at 500°C, piezoelectric constant of ∼15.3pC/N and hardness value of ∼3.57GPa. These values are two orders of magnitude, over two times, and 1.36 times higher than those of pure CBN ceramic, respectively. This work provides a reference for exploring other bismuth-layered structural ceramics.

Vinylene-linked covalent organic frameworks(COFs) are a class of promising porous organic materials that feature fully π-conjugated structures, high crystallinity, permanent porosity, ultrahigh chemical stability, and extraordinary optoelectronic properties. Over the past 5 years, this kind of material has been witnessed rapid development either in chemical synthesis or in potential applications. In this review, we summarize the chemistry to synthesize vinylene-linked COFs, especially the synthetic strategies involving activation of aryl methyl groups for condensation reaction. We then scrutinize the state-of-the-art development in properties and functions of this kind of COFs. Our own opinions on the further development of the vinylene-linked COFs are also presented for discussion.

Reticular chemistry based on thermodynamically controlled linking modes and numerous organic building blocks has constituted versatile crystalline frameworks in molecular-level precision. However, vinylene-linked covalent organic frameworks (COFs) are still quite far from flexible tailoring in either their structures or topologies, due to the lack of monomers with sufficient activities. Herein, we establish a strategy to synthesize vinylene-linked COFs via Knoevenagel condensation between a tetratopic monomer 2,2′,6,6′-tetramethyl-4,4′-bipyridine (TMBP) and linear aromatic dialdehydes in a mixed solvent of benzoic anhydride and benzoic acid. Mechanistic investigation suggests that the condensation was promoted by a pyridine self-catalyzed benzoylation upon the cleavage of benzoic anhydride solvent molecules. The layered structures of the resultant COFs are highly crystallized into orthorhombic lattices with vertically aligned AA stacking modes, delivering high surface areas up to 1560 m2g–1. The π-extended conjugated skeletons comprising para-bipyridyl units and vinylene linkages endow these COFs with substantial semiconducting properties, releasing visible-light-stimulated catalytic activity in water-splitting hydrogen evolution with a rate as high as 3230 μmol g–1h–1.

Conductive carbon structure has been considered as a promising sulfur-hosting material as the cathode of lithium-sulfur batteries. However, the issue of polysulfide shuttling requires an additional component to help restrict and convert sulfur substances. Herein, in this work, hollow and porous carbon nanospheres (HCS) are synthesized by a template method and a high-temperature carbonization treatment. A thin layer of ZnS coating is then deposited on the HCS-based sulfur (ZnS@HCS/S) cathode with controlled thickness, and the overall electrochemical properties are systematically evaluated. Results show that with 30 nm-thick ZnS coating, the cathode reveals an improved capacity of 1411 mA h g−1, and higher capacities from 0.2 to 3 C rate compared with bare HCS/S cathode. Moreover, the ZnS coating also enhances the cycling stability of ZnS@HCS/S cathode over 280 cycles at 0.5 C, with only 0.2% capacity decay per cycle. This work demonstrates potential applications for high-performance lithium-sulfur batteries.

Niobium has a wide range of application in various industries such as materials, alloy, and electronic industry. To improve the use of ilmenorutile in China's Bayan Obo deposit, a novel process of extracting niobium, titanium, and iron from ilmenorutile by NaOH roasting-H2SO4leaching process (NRHLP) was proposed. The influences of roasting and leaching temperature, roasting and leaching time, molar ratio of NaOH-to-ilmenorutile, leaching mass ratio of liquid-to-solid, and the H2SO4concentration on the extraction of niobium were systematically investigated. The results demonstrate that this process is efficient. The optimized reaction parameters were as follows: roasting temperature, 550 °C; molar ratio of NaOH-to-ilmenorutile, 2.6; roasting time, 120 min; leaching mass ratio of liquid-to-solid, 4.0; leaching temperature, 90 °C; the H2SO4concentration, 60 wt.%; leaching time, 2 h. Under these optimum circumstances, the maximum niobium and titanium recovery can reach 96.68%. In addition, a new phase containing niobium and titanium is confirmed and proved.

Various interlayers developed recently for inserting between the cathode and the anode of Li-S batteries to improve the energy storage performance have been discussed and analyzed.

In a new vanadium extracting process, the effective separation of Na3VO4from the aqueous NaOH solution containing impurities of Na2CO3, NaAlO2, or Na2SiO3plays a significant role. The solubility data of NaOH-Na3VO4-H2O system and NaOH-Na2CO3-Na3VO4-H2O system at 298.15, 313.15, and 353.15 K were measured. The Na3VO4solubility in NaOH solutions containing 30.4 g·L–1NaAlO2or Na2SiO3at 313.15 and 353.15 K were also studied for comparison. Na2CO3has a strong salting-out effect on Na3VO4with NaOH molality <7 mol·kg–1. Moreover, NaAlO2and Na2SiO3have a little inhibitory effect on the Na3VO4solubility, and the effect of NaAlO2is more significant. The equilibrium solid phases of sodium orthovanadate in the above systems were identified, which mainly presented Na3VO4·12H2O at NaOH molality <10 mol·kg–1and Na3VO4at NaOH molality >10 mol·kg–1. The determined solubility data and equilibrium solid phases are essential in optimizing the operating parameters for Na3VO4crystallization from actual NaOH solutions. To balance the crystal purity and vanadium recovery, a strategy has been proposed for the effective separation of Na3VO4by evaporation/cooling crystallization after decreasing the Na2CO3concentration.

ZIF-derived carbon structures are considered as desired electrode materials for supercapacitors due to their high surface area, high conductivity, and porous structure. However, the most reported ratio of 2-methylimidazole and Zn(II) is 4:1 to 20:1, which limits commercial applications due to the increasing cost. In this paper, a multirole Zn(II)-assisted method is presented from Zn(II) solution, ZnO, ZnO/ZIF-8 core-shell nanostructure, to 3D hierarchical micro-meso-macroporous carbon structures with a 1:1 ratio of 2-methylimidazole and Zn(II). The hierarchically porous carbon has a high surface area of 1800 m2g−1due to the synergistic effect of multirole Zn(II). The unique carbon-based half-cell delivers the specific capacitances of 377 and 221 F g−1at the current densities of 1.0 and 50 A g−1, respectively. As a 2.5 V symmetrical supercapacitor, the device reveals a high double-layer capacitance of 24.4 F g−1, a power density of 62.5 kW kg−1, and more than 85.8% capacitance can be retained over 10000 cycles at 10 A g−1. More importantly, the low-cost hierarchically porous carbon could be easily produced on a large scale and almost all chemicals can be reused in the sustainable method.

In order to investigate the influence of Cl−/SO42−molar ratios and hydrolysis temperature on the hydrolysis process and TiO2pigment, H2TiO3was prepared with a low concentration of titanyl sulfuric–chloric acid solution by hydrothermal hydrolysis. Under the optimal hydrolysis conditions, 1.5–2.2 μm of H2TiO3samples were achieved. After doping and calcination, anatase TiO2pigments demonstrated excellent performance: the achromic ability of tinctorial strength (TCS) and blue phase index (SCX) were 1,429 and 4.07, respectively. As hydrolysis was a significant step in the process, the structure was simplified to a periodic structure of Ti[OH](H2O)3Cl(SO4) to simulate the cluster structures. Based on experimental results and density functional theory (DFT) calculation, the hydrolysis mechanism was presumed to be a process of anionic (OH−, Cl−and SO42−) competition reaction to explain the formation of anatase‐type H2TiO3, and the crystal growth direction of H2TiO3was also confirmed to be a(OA) and b(OB). Synthesis of qualified anatase TiO2with pigment standard from low concentration of titanyl sulfuric – chloric acid solution. Preparation of H2TiO3intermediate with suitable grain size and agglomerate size by controlling hydrolysis temperature, and concentration of Cl−/SO42−anion. The formation mechanism of anatase‐type H2TiO3and its corresponding intermediate structures are investigated by DFT calculation.

An organic ligand-free solution method is developed for preparing homogeneous core–shell quantum-dot (QD)-modified pure Cs4PbBr6microcrystals on a large scale (∼12 g) at room temperature. The ligand-free Cs4PbBr6microcrystals show a high green photoluminescence quantum yield of 76% with 360 nm of excitation light, which is attributed to their unique microarchitecture, with several features including quantum confinement of the outer QDs, stability of the inner Cs4PbBr6microcrystals, improved light trapping, and interfacial recombination. UV–vis–near-IR and photoluminescence analyses provide valued evidence to support the ligand-free Cs4PbBr6with synergy between the QDs and microcrystals.

Lithium–sulfur (LiS) battery has been considered as one of the most promising rechargeable batteries among various energy storage devices owing to the attractive ultrahigh theoretical capacity and low cost. However, the performance of LiS batteries is still far from theoretical prediction because of the inherent insulation of sulfur, shuttling of soluble polysulfides, swelling of cathode volume and the formation of lithium dendrites. Significant efforts have been made to trap polysulfides via physical strategies using carbon based materials, but the interactions between polysulfides and carbon are so weak that the device performance is limited. Chemical strategies provide the relatively complemented routes for improving the batteries' electrochemical properties by introducing strong interactions between functional groups and lithium polysulfides. Therefore, this review mainly discusses the recent advances in chemical absorption for improving the performance of LiS batteries by introducing functional groups (oxygen, nitrogen, and boron, etc.) and chemical additives (metal, polymers, etc.) to the carbon structures, and how these foreign guests immobilize the dissolved polysulfides.

A D3h-symmetric hexatopic monomer was first prepared by attaching the three-fold ditopic moiety 2,6-dimethylpyridine to the meta-positions of a phenyl ring. It was further condensed at its six pyridylmethyl carbons with linear ditopic aromatic dialdehydes, resulting in two vinylene-linked COFs with heteroporous topologies, as revealed by powder X-ray diffraction (PXRD), nitrogen sorption, and pore-size distribution analyses, as well as transmission electron microscopy (TEM) image. The linear- and cross-conjugations, respectively, arising from the 2,6-linked pyridines and meta-linked phenylenes in the hexatopic nodes rendered the resultant COFs with well-patterned π-delocalization, allowing for efficiently catalyzing the bromination of aromatic derivatives with the pore-size-dependent conversion yields and regioselectivity under the irradiation of green light.

It is difficult to achieve selective separation and enrichment of different rare earths from high abundance yttrium ores efficiently only dependent on their discrepancy in thermodynamic properties. The present work suggests a new strategy based on non-equilibrium kinetic separation of Er and Tm on the surface of freely rising oil droplets to control the separation order of Y. It is revealed that the mutual separation of Er/Tm is significantly promoted with the separation coefficient of 2.89 during the non-equilibrium extraction with the addition of diethylenetriaminepentaacetic acid (DTPA). The extraction sequence of Tm, Er and Y can be controlled as Tm > Y > Er, thus Y can be selectively enriched during the process of separation of Er and Tm. Such a sequence is subject to the controllable dissociation rates of RE(III)–DTPA complexes and extraction abilities of P507 with the three RE(III) ions. The dissociation rate is dependent on the stabilities of RE(III)–DTPA complexes and follows the sequence of Y(III)–DTPA < Tm(III)–DTPA < Er(III)–DTPA. However, the extraction abilities of the three RE(III) ions follow the sequence of Y(III)–P507 Er > Y to Tm > Y > Er.

Hierarchical urchin-like γ-Al2O3hollow microspheres were prepared by a hydrothermal method followed by a calcination process using Al(NO3)3·9H2O as aluminum source, NH3·H2O as precipitating agent, and P123 as structure-directing agent (SDA). The obtained samples were investigated using X-ray diffraction (XRD), filed emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and N2adsorption/desorption. The influences of P123 concentration, acidic condition, and hydrothermal time on the morphology of product were discussed. P123 has a great influence on ruling the oriented attachment of nanowires and stabilizing the superstructure in the self-assembly process. The 3D urchin-like hollow microspheres have a surface area of 210.2 m2/g and the average pore size is 11.42 nm, which have widely potential application such as catalyst, adsorption, and separation.

The traditional activation methods for carbon fibers (CFs) such as strong acid etching are corrosive, time consuming and heavily polluting. In this paper, we report a fast and environment-friendly method to activate CF by a one-step joule-heating process. With only 10 min treatment, the oxygen content in the fiber surface reaches to 24.6%, and the activated CF with hierarchically porous structure and exfoliated surface layers is obtained. As a fiber electrode, it reveals a specific capacitance of 162 F g−1, which is 125 times of the non-activated CF. Furthermore, the joule-heating activation also facilitates the growth of foreign component on fiber surface and strengthens their interfacial interaction. This work provides a novel approach for the rapid fabrication and functionalization of CF-based devices and composites.

In this paper, a flexible skin inspired by the sudoriferous gland structure of human skin is developed for ultra-thermal protection of hypersonic morphing vehicles. The effect of different coolants and cooling flow rates on the cooling performance of the leading edge is studied using finite element analysis. A wind tunnel experiment is conducted at high temperatures with the heat flux Q= 700 kW/m2, and the results indicate the following: (1) the flexible skin can effectively reduce the surface temperature of hypersonic vehicles; (2) when using liquid water instead of argon as the cooling medium, the cooling efficiency of flexible skin performs better; (3) when liquid water is used as the cooling medium, the cooling effect peaks at a flow rate of 0.01 m/s, and further increasing the flow rate will not benefit cooling efficiency significantly; (4) the flexible skin can withstand extreme thermal environments, demonstrating its feasibility in applications of over-limit thermal protection for hypersonic morphing vehicles. This study aims at optimizing the cooling performance of the flexible skin for ultra-thermal protection. The proposed skin can overcome the heat-resistance limit of flexible materials with morphing properties, laying a theoretical and experimental foundation for its future applications in hypersonic morphing vehicles.

Leaf-like hierarchical -AlOOH was prepared by a facile template-free solvothermal method at 150°C for 6 h, using aluminum nitrate (Al (NO3)39H2O) as aluminum source and a mixed water/ethanol solution as solvent. The obtained sample was characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and N2 adsorption/ desorption technique. Experiment results indicated that the obtained leaf-like hierarchical -AlOOH exhibited a BET surface area of 190.3 m2/g and an average pore widths of 18.82 nm. The hierarchical -AlOOH showed excellent removal efficiency for Cr (VI), Methyl orange and Congo red with maximum adsorption capacity of 7.4 mg/g, 59.9 mg/g and 99.0 mg/g, respectively.

Monodispersed, uniform, and hierarchical calcium tungstate (CaWO4) microsphere structures were synthesized through a template-free hydrothermal synthesis using calcium chloride (CaCl2) and sodium tungstate dihydrate (Na2WO4•2H2O) as precursors, sodium phosphate dodecahydrate (Na3PO4•12H2O) was used as structure-directing agent. The obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A possible formation mechanism of the spherical CaWO4 was proposed based on the experimental results. In addition, the fluorescence properties of the CaWO4 were studied. Experiment results indicated that the obtained CaWO4 microspheres were assembled by nanoparticles of 30-100 nm in diameter, PO4 3- played a crucial role in the self-assembly process of the hierarchical structure. Moreover, CaWO4 microspheres showed good fluorescence performance.

For medical diagnosis, fuzzy Dempster-Shafer theory is extended to model domain knowledge under probabilistic and fuzzy uncertainty. However, there are some information loss using discrete fuzzy sets and traditional matching degree method. This study aims to provide a new evidential structure to reduce information loss. This paper proposes a new intuitionistic fuzzy evidential reasoning (IFER) approach which combines intuitionistic trapezoidal fuzzy numbers and inclusion measure to improve the accuracy of representation and reasoning. The proposed approach has been validated by a stroke diagnosis. It is shown that the IFER approach leads to more accurate results.

AbstractFor medical diagnosis, fuzzy Dempster-Shafer theory is extended to model domain knowledge under probabilistic and fuzzy uncertainty. However, there are some information loss using discrete fuzzy sets and traditional matching degree method. This study aims to provide a new evidential structure to reduce information loss. This paper proposes a new intuitionistic fuzzy evidential reasoning (IFER) approach which combines intuitionistic trapezoidal fuzzy numbers and inclusion measure to improve the accuracy of representation and reasoning. The proposed approach has been validated by a stroke diagnosis. It is shown that the IFER approach leads to more accurate results.

Filling with high dielectric constant inorganic nanoparticles is an effective approach to enhance the energy storage performance of an organic dielectric. However, the dielectric mismatch between ceramic and polymer causes early breakdown, which limits the storage density of ceramic/polymer nanocomposites in the application of dielectric capacitors. Herein, we employed MgO as a buffer barrier to mitigate the mismatched dielectric characteristics among BaTiO3(BT) nanoparticles and poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) substrate considering its high insulation and medium dielectric constant. The alien oxide was coated on the spherical BT by a simple chemical precipitation process, forming a BaTiO3@MgO (BT@MgO) core-shell nanostructure, which has been carefully examined by TEM and EDS. The BT-MgO heterogeneous interfacial region provides channels for carriers and promotes charge movement, and therefore the dielectric constant and potential shift have been significantly enhanced. The BT@MgO/P(VDF-HFP) nanocomposite with 1 vol% filling ratio delivered a maximum energy density Ud, and the value reaches up to 5.6 J/cm3that is 40.0 % and 55.6 % greater than that of the host matrix and BT-filled counterpart with the same filler amount. The BT@MgO core-shell nanostructure demonstrates an alternative way to effectively heighten the energy storage performance of ceramic/polymer composite dielectrics.

Carbon nanotube (CNT) arrays show great promise in developing anisotropic thermal conductive composites for efficiently dissipating heat from high-power devices along thickness direction. However, CNT arrays are always grown on some substrates and liable to be deformed and broken into pieces during transfer and solution treatment. In the present study, we intentionally synthesized well-crystallized and large-diameter (∼80 nm) multiwalled CNT (MWCNT) arrays by floating catalyst chemical vapor deposition (FCCVD) method. Such arrays provided high packing density and robust structure from collapse and crack formation during post solution treatment and therefore favored to maintain original thermal and electrical conductive paths. Under optimized condition, the CNT arrays can be transferred into flexible composite films. Furthermore, the composite film also exhibited excellent thermal conductivity at 8.2 W/(m·K) along thickness direction. Such robust, flexible, and highly thermal conductive composite film may enable some prospective applications in advanced thermal management.

A composite film with switchable transparency is fabricated by sandwiching a carbon nanotube (CNT) sheet within polyurethane (PU) films. The introduction of CNTs not only makes the composite film electrically conductive but also induces a rapid crystal melting of soft segments in the PU. As a result, the film can be switched from opaque to transparent in just several seconds after turning on voltage, and reversed back to opaque after turning off voltage. The film also possesses several other attractive properties, including excellent flexibility, low energy consumption, switching speed insensitivity to ambient temperature, and easy coloration, which make the film promising for a wide variety of practical applications.

Two-dimensional Ti3C2TxMXene nanosheets with excellent electrical conductivities have been synthesized in this work. The nanosheet is further assembled with air-laid paper and polydimethylsiloxane substrate, for sensing both tensile and torsional deformations. Results show that the sensor is able to detect a linear stretchability of up to 90% with the corresponding gauge factor of 1–2.58. After repeated stretching and releasing cycles at a strain of 10% for 2000 cycles, the remaining change of relative resistance is only 0.1. Particularly, the sensor also displays responsive electrical signal change when torqued from 0 to 2π radian, suggesting a potential application for torsion deformation detecting. For demonstration, the sensor is applied in real-time monitoring the physiological movements, revealing outstanding capability of recognizing motions of finger bending, squat/rise, speaking and twisting.

To make use of scrap perovskite titanium slag to produce metatitanic acid, a new method based on the high efficiency decomposition ability of sulfuric–chloric mixture acid (SCMA) has been proposed. Because Al is one of the most common elements existing in its raw state, Al3+has become the main impurity in titanium solutions after decomposition, which affects the performance of related products. Consequently, the role of Al on the thermal hydrolysis of Ti in the SCMA solution was investigated in this study. With the addition of Al3+, a lower hydrolysis ratio was obtained at a low reaction temperature (130 °C). Moreover, the particles of metatitanic acid displayed a ball-shaped morphology and narrow particle distribution with a D50of 1.4–2.0 μm. According to the crystal structures of Al3+, it is presumed that the priority order of ligand is SO42−>H2O>Cl−. The addition of Al3+increases the growth rate of the a- and b-axes but reduces the growth rate of the c-axis. The results presented here confirm the influence of Al3+in the control of nucleation and growth process during the hydrolysis to achieve qualified metatitanic acid products.