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The development of stable, high-energy electrode materials for lithium ion-batteries requires an elaborate effort to optimize the active materials as well as the chemical bonds and electron/ion transport in the electrode. However, hindered by the intrinsic structure and electrochemical degradation which is attributed to the volume expansion of materials, an increase in battery safety and reliability is concerned. Here, taking silicon as an example, we propose a strategy to stabilize this anode by successive chemical bonds reconstructing the surface. In this study, silicon nanoparticles are assembled in a carbon-copper framework via a facile and scalable pyrolysis process to provide a short-range electron transfer and pulverization suppression. Dissimilar to the current carbon coating methods, with the aid of Cu-O-C, Si-O-C, and Si-C chemical bonds, silicon hybridized reduced graphene oxide (rGO) and double-faced adhesive tape derived carbon composite (Si+rGO@DFAT-C) exhibits high structural integrity and immune to delamination. Hence, it demonstrates superior capacity (1536 mAh g at 0.1 A g ), high rate capability (1126 mAh g at 2 A g ), and stable electron stability (968.1 mAh g after 200 cycles at 0.5 A g ). This study emphasizes the crucial importance of well-tailor surface chemical bond reconstruction for the anode stabilization for high-performance LIBs. −1 −1 −1 −1 −1 −1

A pressureless solid-liquid reaction method was used to prepare β-Yb2Si2O7 powders in this article. Effects of different metallic oxides (Li2O, MgO and Al2O3) on synthesis process and high-temperature dielectric properties of β-Yb2Si2O7 were systematically studied. Chemical kinetics of synthesis process was calculated, and the apparent activation energy of Yb2O3/SiO2/Li2O, Yb2O3/SiO2/MgO, Yb2O3/SiO2/Al2O3 systems was calculated to be 42.98, 63.48, and 74.33 kJ/mol, respectively, which decreased by 77.3%, 66.5%, and 60.7% compared with that in additives free system. However, the microscopic network structure of intercrystalline glass phase formed by Li2O or MgO was looser than Al2O3 additive, leading to an intense structural relaxation polarization and a sharp increase in dielectric loss. β-Yb2Si2O7 prepared by adding Al2O3 had the best high-temperature dielectric performance. Its dielectric constant was less than 6, and the dielectric loss tangent was less than 2.5 × 10−2 from room temperature to 1200 °C in the range of 7–18 GHz. Such excellent dielectric property gave it the potential to be used as a wave-transmitting component at high temperature.

Rare earth double tungstates Na(Gd,RE)(WO4)2 (RE = Eu/Yb-Er) were successfully obtained from layered rare earth hydroxide precursors via sacrificial reaction at 200°C with molar ratio WO42-/RE3+ = 2.5 for 24 h reaction without calcination and the employment of any organic reagents. The temperature sensing performances of Na(Gd,RE)(WO4)2 (RE = Eu/Yb-Er) were comparatively investigated by analyzing the temperature-dependent down-conversion (DC) and up-conversion (UC) luminescence spectra. The DC phosphors Na(Gd,Eu)(WO4)2 were found to be well capable of sensing temperature via fluorescence lifetime (FL) mode. The UC phosphors Na(Gd,Yb,Er)(WO4)2 were capable of sensing temperature via both FL mode and fluorescence intensity ratio (FIR) mode through thermally coupled 2H11/2,4S3/2 levels (I520/I552), and non thermally coupled 2H11/2,4F9/2 energy levels (I520/I670). The UC phosphors Na(Gd,Yb,Er)(WO4)2 have maximum absolute sensitivity (SA) and maximum relative sensitivity (SR) of 174 × 10−4 K−1 (548 K) and 80 × 10−4 K−1 (298 K) for the thermally coupled 2H11/2,4S3/2 levels and maximum SA and SR of ~260 × 10−4 K−1 (300–550 K) and 96 × 10−4 K−1 (298 K) for the non-thermally coupled 2H11/2,4F9/2 energy levels.

Although metal silicates are considered as the promising electrode materials for lithium-ion batteries, metal silicate-based materials suffer from inadequate cycling performance and dimensional unreliability evoked by the large volume changes during cycling, which hinders their practical applications. In principle, the poor electrochemical kinetics during the redox reactions of metal silicates is originated from the instinct structure. Hence, the precise and delicate ability to construct hetero-layers to tailor intercalation reaction remains elusive. Herein, a facile strategy of designing and constructing heterostructure in a cobalt-copper silicates nano-architecture (CNT@CoCuSiOx) with synergistic interaction between cobalt silicate (Co2SiO4) with copper silicate (CuSiO3) on the surface of carbon nanotubes (CNTs). Moreover, Co2SiO4/CuSiO3 heterojunction with unbalanced charge distributions that rooted from in-situ generation on CNTs by a facile one-step hydrothermal process, can efficiently tailor the electrochemical activities of Cu3+/Cu2+ and Co3+/Co2+ redox reactions by elevating transfer of electrons and delivering the heterointerface effect. The tough and conductive nanostructure of CNTs basement facilitate the ion diffusion and improve the rate capability. The heterostructure-incorporated CNT@CoCuSiOx-(2/1) exhibits not only outstanding electrochemical capacity (545 mAh g−1 at 0.1 A g−1), superior ion/electron transmission efficiency but also robust cycling performance (516 mAh g−1 after 900 cycles at 0.5 A g−1 and an excellent capacity retention rate of 95%). Beyond energy storage, our delicate methodology in manipulating the electrochemical behavior of metal silicates opens up a critical insight into rational fabrication of next-generation anodes for lithium-ion battery.

Dense γ-Y2Si2O7 ceramics were prepared by moulding and sintering of pure γ-Y2Si2O7 powders synthesized by adding various additives. Effects of sintering additives on hot corrosion behavior of γ-Y2Si2O7 ceramics in Na2SO4 + V2O5 molten salts were systematically investigated. Chemical kinetics of corrosion process was also calculated to illuminate the influence of different additives on chemical stability. Results showed that corrosion reaction started at grain boundary due to the loose microscopic network. When the intercrystalline glass phase was completely etched, the molten salts began to contact Y2Si2O7, forming NaY9Si6O26 and YVO4. Compared with Li2O and MgO, intercrystalline glass phase formed by Al2O3 additive had the most compact microscopic network structure, leading to the best chemical stability. Apparent activation energy for hot corrosion reaction of γ-Y2Si2O7 ceramics in pure Na2SO4, Na2SO4 + 5 wt% V2O5, Na2SO4 + 10 wt% V2O5, Na2SO4 + 15 wt% V2O5 molten salts was calculated to be 408.16, 373.60, 310.62, and 249.63 kJ/mol, respectively.

Tetragonal structured LaVO4 (t-LaVO4) is superior to its thermodynamically stable monoclinic polymorph for luminescence, but is difficult to synthesize without using chelating molecules/ions. With Ln2(OH)4SO4·2H2O layered hydroxide as an original template for phase conversion, well-crystallized t-(La0.95Eu0.05)VO4 nanocrystals (∼40–80 nm) of favorable dispersion and size uniformity were directly produced via hydrothermal reaction at 200 °C for 24 h without using any organic additive. Luminescence analysis showed that the as-made nanocrystals have an absolute quantum yield of ∼38.2%, fluorescence lifetime of ∼1.52 ms and color coordinates of around (0.33, 0.65) under 304 nm UV excitation at room temperature (RT), and the 620 nm main emission can retain as high as ∼66% of its RT intensity at 150 °C. The activation energies for thermal quenching were analyzed to be ∼0.321, 0.286 and 0.291 eV for the 537 nm (5D1 → 7F1 transition), 593 nm (5D0 → 7F1) and 620 nm (5D0 → 7F2) emissions of Eu3+, respectively. Application of the nanocrystals in LED lighting found electric-field enhanced 5D0 → 7F4 emission of Eu3+ (∼697 nm) and increasing brightness but relatively stable color correlated temperature (∼3270–3400 K) at a higher driving current (30–100 mA) for the lamp. The nanocrystals were also demonstrated to be well capable of temperature sensing with the I537/I593 fluorescence intensity ratio, whose maximum absolute sensitivity, maximum relative sensitivity and minimum temperature resolution are ∼0.27% K−1, 2.01% K−1, and 0.015 K at 298 K, respectively.

In order to prevent water from entering the porous Si3N4 ceramics, α-Si3N4 whiskers toughened γ-Y2Si2O7 coatings were prepared by a liquid infiltration and filling method. Effects of α-Si3N4 whiskers content on the microstructure, waterproof performance, mechanical properties and thermal shock behavior of the ceramic coatings were systematically studied in this paper. Results indicated that the addition of whiskers could effectively improve the performance of the coatings under thermal shock due to the toughening mechanism of whiskers including crack deflection, whisker bridging, whisker pulling out and other energy dissipation processes. The coating with a α-Si3N4 whisker/γ-Y2Si2O7 mass ratio of 1/9 possessed a flat, dense and defect-free surface microstructure. After five thermal cycles under a thermal shock temperature difference of 1200 °C, water absorption of the coating increased slightly from ~3.2% to ~6.0%. The whisker reinforced coating is promising to be used for high temperature wave-transmitting materials in long-time service.

Creatively constructing Z-scheme composites is a promising and common strategy for designing effective photocatalyst systems. Herein, we synthesized Z-scheme Fe2O3@Ag-ZnO@C heterostructures from the Fe-MOFs and applied it to photodegradation of tetracycline and methylene blue pollutants in wastewater. The optimized sample exhibits a remarkable performance as well as stability under visible light irradiation. The calculating and experimental results demonstrate that the Fe2O3@ZnO nanointerface and carbon sheath together boost the transfer efficiency of photogenerated carriers and absorption ability, thereby improving the photocatalytic activity. Furthermore, detailed mechanism investigation reveals the pivotal role of reactive oxygen species (•OH and •O2-) generated, resulting in remarkable performance. In addition, cell biology experiments reveal that the wastewater after photocatalytic treatment has good biological compatibility, which is important for applications. This work provides valuable information for constructing high-performance Z-scheme photocatalysts from MOFs for environmental treatment.

The stereospecific design of the interface effects can optimize the electron/Li-ion migration kinetics for energy-storage materials. In this study, an electric field was introduced to silicon-based materials (C-SiOx@Si/rGO) through the rational construction of multi-heterostructures. This was achieved by manipulating the physicochemical properties at the atomic level of advanced Li-ion batteries (LIBs). The experimental and density functional theory calculations showed that the unbalanced charge distribution generated a large potential difference, which in turn induced a large-scale electric-field response with a boosted interfacial charge transfer in the composite. The as-prepared C-SiOx@Si/rGO anode showed advanced rate capability (i.e., 1579.0 and 906.5 mAh g-1 at 1000 and 8000 mA g-1, respectively) when the migration paths of the Li-ion/electrons hierarchically optimized the large electric field. Furthermore, the C-SiOx@Si/rGO composite with a high SiOx@Si mass ratio (73.5 wt %) demonstrated a significantly enhanced structural stability with a 40% volume expansion. Additionally, when coupled with the LiNi0.8Co0.1Mn0.1O2 (NCM) cathode, the NCM//C-SiOx@Si/rGO full cell delivers superior Li-ion storage properties with high reversible capacities of 157.6 and 101.4 mAh g-1 at 500 and 4000 mA g-1, respectively. Therefore, the electric-field introduction using optimized electrochemical reaction kinetics can assist in the construction of other high-performance LIB materials.

ZnS nanobelts have been synthesized by a reaction of Zn and S powders using the simple arc discharge method. The products were characterized using X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, as well as energy-dispersive X-ray spectrometer. The results reveal that the ZnS nanobelts exhibit bicrystalline nanostructure. The roles of ion bombardment and plasma species in the growth of bicrystalline ZnS nanobelts are discussed. The ZnS nanobelts exhibit strong emission peaked at 516 nm under a 373 nm UV light excitation and excellent photocatalytic ability for degradation of methylene blue. This work represents a new strategy to synthesize bicrystalline nanostructures for design of optoelectronic nanodevices and photocatalysts.

Two-dimensional (2D) intrinsic ferromagnetic semiconductors with high magnetic anisotropy (MA) and Curie temperature (TC) are desirable for low-dimensional spintronic applications. We present here the structural stability, MA and TC of the semiconducting NiI2 monolayer under strain from -4% to 4% using first-principles calculations. The unstrained NiI2 monolayer exhibits an in-plane magnetic anisotropy energy of -0.11 meV per unit cell and a TC of 79 K. Most noteworthily, the in-plane MA and TC of the NiI2 monolayer are simultaneously enhanced under compressive strain; meanwhile, the NiI2 monolayer is still stable. In particular, when the compressive strain reaches -4%, the in-plane MA is more than three times higher than that in the unstrained system. Based on the second-order perturbation theory of spin-orbit coupling, the density of states and the orbital magnetic anisotropy contributions are analyzed, indicating that the compressive strain effect originates from the increase of the negative contribution from the spin-orbit coupling interaction between the opposite spin py and px orbitals of the I atom. This study provides a promising route for exploring new 2D ferromagnetic semiconductors with higher MA and TC.

This study aimed at investigating the molecular level organization and photoluminescence in the interlayer space of magadiite (mag) synthesized by the process of solid-state intercalation. Host-guest composites were prepared by an easy grinding process without other operation. Detailed structural investigations were performed by powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), energy-dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Thermo-gravimetric analysis and differential thermal analysis (TGA/DTA), field emission scanning electron microscopy (FE-SEM), Ultraviolet-visible spectroscopy (UV–Vis), photoluminescence (PL) and inverted fluorescence microscope. Results confirmed that 8-hydroxyquinoline (8Hq) was intercalated in the interlayer space of mag in the presence of various metal ions (Ca2+, Zn2+ and Mn2+) inside. Basal spacings between silicate layers were controlled by exchanged metal ions and decorated 8Hq. Solid-state intercalation resulted in the lower proportion of intercalated 8Hq, but good luminescence was observed by PL. The complexes in the interlayer space showed special fluorescence properties. A speculative mechanism was proposed for reaction by solid-solid intercalation. This study provided a message for understanding the functional properties of composites 8Hq/Ca, Zn, Mn-mags, such as loading capacity and photoluminescence properties.

Currently used aqueous electrolytes for lithium-ion batteries suffer from narrow potential windows of

The quantitative optical analysis method, as the development trend of mixture quantitative analysis, has the advantages of fast, non-contact and real time online detection. The refractive index spectra contain information of mixture, which are regarded as the basis for establishing quantitative optical analysis model. Compared with the traditional transmittance or reflectance spectra, the refractive index spectra based on mixing rule can reduce the scale of sample set, and achieves the purpose of simplifying the model. The refractive index spectra contain not only useful information, but also other useless information such as noise. Thus, the effect of spectral pretreatment on the prediction ability was compared due the existence of the interference information. The mixed gradient and the data type determine the scale of the sample set, which are all the determinant factors of the complexity of the model. Therefore, they were also regarded as factors that influence the prediction ability of the M-D-iPLS model. It is found that the M-D-iPLS-0.05 model based on the spectral pretreatment has better prediction performance.

The high performance of a supercapacitor device relies largely on the nanoarchitectures scrupulous designed and electrode material used. In this work, by utilizing Stober method-prepared SiO2 sphere as a template, porous hollow spherical nanostructured metal silicates (MnSi, CoSi and NiSi) were synthesized by a hydrothermal method. When MnSi, CoSi and NiSi were used as effective positive materials for asymmetric supercapacitor, they exhibited a battery-type redox behavior and a relatively high charge storage property (517.0, 452.8, 66.7 F g−1 at 0.5 A g−1) in an aqueous alkaline electrolyte. The excellent electrochemical performance is mainly based on the large surface area of metal silicates, and the porous hollow spherical structure facilitates fast electrolyte ions and electrons transportation. More importantly from the practical applications, three high capacity performance, flexible asymmetric solid-state supercapacitor devices were assembled by employing metal silicates as an effective positive electrode and activated carbon as negative material in PVA-KOH gel electrolyte. The MnSi//AC, CoSi//AC and NiSi//AC device showed an areal capacitance of 1048.3, 375.5 and 120.9 F cm−2, corresponding to a high energy density of 4.6, 2.6 and 0.93 mWh cm−3, respectively. The detailed formation mechanism and electrochemical mechanism of metal silicate is performed experimentally and theoretically. The results reveal that MnSi, CoSi and NiSi have a potential application in energy storage.

Low cost and high-performance electrode materials are essential for supercapacitor development and applications. Herein, this paper reports a cost-effective and easy-operation method to prepare hierarchical structural heteroatoms-doped carbon/copper oxide/cuprous oxide (CuOx@C) nanocomposites using a calcination process and a hydrothermal treatment. When waste bamboo leaves are converted into carbon materials, the unique hierarchical structures and inherent heteroatoms could be maintained. The hierarchical porous structures allow a short diffusion and facile ion-transfer of electrolyte ions to the active materials during the electrochemical reaction. The copper oxide/cuprous oxide nanoparticles are introduced by hydrolysis of copper ions. By controlling the reaction condition, copper oxide/cuprous oxide nanoparticles are dispersed in the carbon. The hybridization of carbon and metal oxide results in a combination of electrical double-layer capacitance and battery-like capacitance. The obtained CuOx@C composite exhibits an excellent specific capacitance of capacity of 147 F g−1 and a long cyclic life of 93% after 10000 cycles of charge-discharge when it is applied as a material for supercapacitor. This work provides a new approach for fabrication of metal oxide/carbon nanocomposites for application in energy storage.

Optical glass which usually has specific optical constants is the basic material of optical system of optical instruments and optical machinery. In order to accurately calculate the optical constants of optical glass, two models (PTT method and PTR method) were established for the quartz glass taking quartz glass as the research object. The application range and precision of the two methods were compared, and the influence of transmittance deviation on the accuracy of the two methods was analyzed. Both of the two methods have wide application scope and high accuracy. Under the influence of transmittance deviation, the PTR method has higher precision in calculating refractive index and the PTT method has higher precision in calculating absorption index. Therefore, the two methods are complementary to each other in resisting transmittance deviation.

A novel nanocomposite containing polymer and iron-oxide nanoparticles in the interlayer space of layered silicate magadiite (mag) was synthesized by ion-exchange and co-precipitated method. Mag was first modified with poly(oxypropylene)amine salts (POP at 2000 and 4000 g/mol Mw). The interlayer space could be effectively expanded from 1.5 to 6.4 and 11.4 nm, respectively, by controlling the amount of POP intercalated. The expanded basal space is suitable for iron oxide nanoparticles embedded. During the ion-exchanging and co-precipitating of iron species, there's an unwanted “crowding-out effect” that release POP molecules, which lead to the mag couldn't encapsulate iron oxide nanoparticles in a certain amount. The existence of high molecular weight POP4000 and low temperature (

Hydrogen and other renewable resources derived by sunlight have attracted great attention to sustainable development. But the photochemical performance of diverse systems is restricted because of the poor efficiency of photon absorption, easy recombination of photogenerated electron–hole pairs, and slow transfer of charge carriers. Single-atom catalysts (SACs), in which isolated atoms are supported on the supports without forming nanoparticles, have received increasing interests in photocatalysis due to the high catalytic activity, selectivity, stability, and 100% atom utilization. In this review, we highlight and introduce recent advances in the preparation method of SACs and concrete examples of single-atom photocatalysts used for the hydrogen evolution from water, overall water splitting, CO2 and N2 reduction reaction. At last, we discuss the underlying mechanisms for photocatalytic performance of single-atom catalysts and the prospects for the development of SACs.

Cerium doped aluminum nitride (AlN:Ce) hierarchical nanostructures were fabricated by a direct reaction of Al and CeO2 mixed ingot with ammonia using modified arc discharge method. X-ray diffractometry, Raman spectrum and x-ray photoelectron spectroscopy analysis obviously indicated that Ce3+ ions incorporated inside the AlN nanostructures. The prepared AlN:Ce exhibited a strong red-orange emission at 600 nm and showed room temperature ferromagnetism. These results suggest that AlN:Ce hierarchical nanostructures have potential as a light-emission nanodevice and diluted magnetic semiconductor.

Manganese silicate/graphene oxide (MnSiO3/GO) composite was successfully synthesized using GO, manganese chloride and sodium silicate through a facile precipitation method. The results show MnSiO3 nanoparticles are closely dispersed on GO sheets, suggesting the formation of a united composite. This composite exhibits a large specific surface area of 161 m2 g−1 and a pore volume of 0.8728 cm3 g-1. MnSiO3/GO composite displays high electrical conductivity and fast ion and electron transport, which can improve the electrochemical performance of MnSiO3. To be specific, MnSiO3/GO composite delivers the specific capacitance as high as 262.5 F g−1 at 0.5 A g−1 in 1 M Na2SO4 electrolyte, which is higher than that of MnSiO3 (168.8 F g−1) and GO (4.6 F g−1). This finding proves that MnSiO3/GO composite can be considered as a promising candidate material applied to high-performance energy storage device.

We demonstrate the growth of ZnSe microspheres in large quantities by using a mixture of Zn and Se as precursors via direct current arc discharge method without the addition of any catalyst or template. The as-obtained samples were characterized by X-ray diffraction, Raman, energy-dispersive X-ray spectrometry, scanning and transmission electron microscopy, and ultraviolet-visible reflectance spectroscopy. The majority of the ZnSe microspheres which were composed of ZnSe nanoparticles exhibited perfectly spherical morphology and a distinct hollow structure with a relatively rough surface. The growth mechanism of ZnSe hollow microspheres has been discussed. Room-temperature excitation and emission spectra as well as the fluorescence lifetime of ZnSe hollow microspheres were measured and the results showed ZnSe hollow microspheres exhibit an intensive wide broad emission bands from 550 to 750 nm upon 470 nm excitation with fast decay time 1.09 ms and CIE chromaticity coordinates (0.65, 0.34), which was ascribed to characteristic structure defects (vacancies and interstitials) in ZnSe. Additionally, the temperature dependent emission behavior was measured and discussed.

Traditional electro-Fenton systems must continuously supply oxygen to the cathode, which leads to extensive volatilisation of benzene in solutions. In this study, we adopted a floating cathode electro-Fenton system without bubbling oxygen into the solution to treat benzene-containing wastewater. The effects of the floating cathode position and main reaction parameters on benzene degradation were analysed, and the degradation cost was estimated. The results indicated that the electro-Fenton system with floating cathode could effectively degrade benzene in solutions. For the cathode, the complete utilisation of air and oxygen released from the anode was crucial. The benzene degradation rate increased with an increase in benzene concentrations. Additionally, pH mainly affected the existing ionic state of iron and production ratio of active substances. The current intensity significantly influenced the reaction activity. Using the floating cathode electro-Fenton method, the benzene removal ratio in the solution could reach 74.80% after 60 min under the optimum reaction conditions. For the floating cathode electro-Fenton system, the cost of treating benzene-containing sewage per cubic metre was $1.2187, which is significantly lower than that for traditional electro-Fenton technology ($1.4000). Hence, the floating cathode electro-Fenton system is an economical and efficient method for benzene degradation in solutions. HIGHLIGHTS •A floating cathode electro-Fenton system was used for the treatment of benzene-containing wastewater.; •The problem of benzene volatilisation was solved during the electro-Fenton degradation process.; •The floating cathode electro-Fenton is an economical method for the wastewater treatment.

The parallel ultrafine SiO2 nanowires coated with amorphous SiO2 have been synthesized by a thermal evaporation method. The samples have been systematically studied by X-ray powder diffraction, Raman spectroscopy, scanning electron microscope, high-resolution transmission electron microscopy, selective area electron diffraction, and photoluminescence. The results show that the synthesized nanowire consists of a composite structure of the amorphous shell and the nanometer-sized crystalline core which has a monoclinic structure. The diameter of the internal one-dimensional crystal structure is about 10 nm. Furthermore, the luminous performance of SiO2 nanowires coated with amorphous SiO2 reveals a stable and strong yellow-red emission band. The products might be suitable for optoelectronic semiconductor application.

International audience; Ligand-induced chirality in colloidal semiconductor nanocrystals attracts attention because of their tunable chiroptical properties. Here, the induced chirality and circularly polarized luminescence (CPL) are investigated as a function of the CdS shell growth in a range of 2D CdSe/CdS nanoplatelets (NPLs) capped with chiral ligands. Five samples of CdSe/CdS NPLs are synthesized by a one-pot approach to vary the island-like shell on a four-monolayer (4 ML) CdSe NPLs core, which effectively reduces the interfacial strain energy. The successful preparation of L-/D-Cysteine-capped CdSe/CdS NPLs with both tunable circular dichroism (CD) and CPL behaviors and a maximum anisotropic luminance factor (glum) of 5.29 × 10−4 is described. The induced chiroptical response shows a direct relationship with the formation of island-like shell in the first and second stages and shows a clear signal evolution. In the third stage with a full coating shell, the CD and CPL signals are inversely proportional to the CdS shell thickness. The island-like shell gives birth to the CPL signal, while the formation of full coating shell decreases the induced chirality. Such chiral and emissive NPLs provide an ideal platform for the rational design of semiconductor nanocrystals with chiroptical properties in areas of biomedicine, polarizers, and new generation of display devices.

Shear thickening fluids (STFs) treated Kevlar fabrics have been widely used to fabricate the flexible body armors and the STFs can be subjected to a variable temperature in many service environments. Therefore, the rheological properties of the STFs prepared by dispersing monodisperse polystyrene (PS) microspheres in polyethylene glycol 200 (PEG200) were investigated at the temperature from −15 °C to 35 °C and the inter-yarns frictional properties of neat and STFs-treated Kevlar fabrics were investigated for six different pull-out speeds at −15 °C and 25 °C to evaluate the contribution of the STFs treatments. The STFs effectively improved the inter-yarns friction and the trigger of shear thickening in STFs-treated fabrics was achieved in some specific speed which was about 50 mm/min for PS/PEG200-based STFs-treated Kevlar fabrics at −15 °C. The improvement of friction caused by the microspheres among the yarns and filaments was demonstrated to be the main reason for the enhancement of the STFs-treated fabrics.

Herein, a facile strategy was developed for the preparation of a nanostructured nickel silicate–nickel hydroxide composite (NiSi–Ni(OH)2) with two types of morphologies, including coated hollow nanospheres (NiSi@Ni(OH)2) and platelet-assembled hollow spheres (Ni(OH)2-Si) as a positive electrode material in hybrid supercapacitors. This strategy involved the use of nano-sized SiO2 derived from the Stober method as the silicon source and a single-step hydrothermal method. The as-synthesized NiSi–Ni(OH)2 composite exhibited a battery-like redox behavior and relatively high charge storage property (476.4 F g−1 at 2 A g−1) when measured in a three-electrode system. It also delivered high stability during long-term cycling (103.3% after 10 000 cycles), which is mainly due to the synergistic effect after the combination of the two materials, where the hollow spherical structures facilitate the fast diffusion of electrolyte ions and enable the fast transmission of electrons. Considering its practical applications, a hybrid asymmetric supercapacitor (HSC) device was assembled using NiSi–Ni(OH)2 as the positive electrode and porous activated carbon as the negative electrode in PVA–KOH electrolyte gel. The HSC exhibited a capacitance of 674.7 mF cm−2 at 2 mA cm−2, corresponding to a maximum energy and power density of 21.6 W h kg−1 (5.2 W h cm−3) and 431.7 mW kg−1 (104.3 mW cm−3), respectively. These properties demonstrate the potential of the hollow-structured NiSi–Ni(OH)2 composite for achieving high-energy and stable energy storage systems.

Supercapacitor performance is reported for manganese silicate hybridized carbon materials (MnSi-C) that is derived from natural bamboo leaves. The in-situ generated manganese silicate is in good distribution by a simple hydrothermal treatment without the addition of another controlling agent. We also study the performance of MnSi-C as a single electrode and a cathode for fabrication of asymmetric supercapacitor device with a Ni(OH)2 anode. Remarkably, the single electrode MnSi-C-3 delivered a capacity of 162.2 F g−1 at a current density of 0.5 A g−1. The cyclic performance of single electrode MnSi-C-3 maintains high capacitance retention of 85% after 10,000 cycles of charge-discharge. By assembled MnSi-C-3 with Ni(OH)2, the asymmetric supercapacitor device shows a capacity of 438.5 mF cm−2 at a scan rate of 4 mA cm−2. The device exhibits an optimal electrochemical performance with an energy density of 3 mWh cm−3 (24.6 Wh kg−1) and power density of 130.4 mW cm−3 (604.8 W kg−1). A reasonable mechanism of in-situ generated manganese silicate on the surface of carbon is proposed based on the experimental data and existed theories. This MnSi-C nanocomposite proves to be a promising electrode material for high energy supercapacitor.

Rice husks (RHs) rich in carbon and silicon elements are one of the worldwide abundant agricultural residues, and they can be a useful source of active materials for energy storage. However, most of the previous research studies concentrated on the use of one of the elements such as carbon or silicon. In order to fully recycle RHs, here, we report a novel hydrothermal process to develop Mn3O4/manganese silicate/C nanostructured composites using RHs as the raw materials. The as-prepared materials possess well- developed porosity with a high specific surface area because of the biomass-derived carbon. The unique structure endows the nanocomposite with desired electrolyte wettability and fast absorbance/desorbance for electrolyte ions. The active materials exhibit excellent performance, with a good capacitance of 108 F g−1 at 1 A g−1 as well as excellent cycling behavior with a retention of 82% after 8400 cycles as a supercapacitor electrode. In addition, the flexible solid-state hybrid supercapacitor (c-MnSi-2//Ni(OH)2) thus derived realizes a maximum energy density of 13.3 W h kg−1 at the corresponding power density of 103.9 W kg−1 and a capacity retention of 81% after 5000 cycles.

The thermal radiative properties of nanofluids have considerable contribution to the effectiveness of harvesting solar energy. In this work, the thermal radiative properties of Al2O3-paraffin nanofluid were experimentally investigated in terms of the influence of volume concentration, nanoparticle size, temperature and optical path. The transmittance spectrums of Al2O3-paraffin nanofluid were measured by a TU-19 FTIR spectrometer which was used for the calculation for the absorption coefficient and reflectivity of nanofluid. The experimental results show that Al2O3-paraffin nanofluid performs excellent ability to absorb solar energy compared to pure paraffin, with higher absorption coefficients increased up to 15.5 times at volume concentration 0.01%. The reflectivity of nanofluid is sensitive to nanoparticle size. When the nanoparticle size decreases from 30 to 10 nm the reflectivity of Al2O3-paraffin nanofluid reduces about 37.04%. With increasing temperature, the absorption coefficient of Al2O3-paraffin nanofluid increases and the reflectivity accordingly decreases.

The yttrium doped AlN (AlN:Y) microtubes, prism-arrayed microstructures and microflowers were fabricated through the direct reaction of Al:Y alloy and N2 without extra catalyst. AlN microstructures can be controlled by varying deposition temperature or changing deposition area. The structure and morphology of AlN:Y microstructures were characterized by X-ray diffraction, scanning and transmission electron microscopy and Raman spectroscopy. The results indicate that Y3+ ions incorporate inside the AlN nanostructures. The photoluminescence spectra of the AlN:Y microstructures show strong defect-induced emissions in the visible range of 400–750 nm. Room-temperature ferromagnetism is observed in AlN:Y microstructures which is caused by high concentration of Al vacancies. The AlN:Y microstructures with interesting geometries possess excellent optical and magnetic properties, suggesting potential applications in optoelectronic and spintronic microdevices.

The partial least square method (PLS) was introduced to quantitatively analyze component content of multivariate mixture by using ultraviolet-visible spectroscopy. Two models were built to establish component content of multivariate mixture based on the transmittance spectra of multivariate mixture, which is the full band PLS model and the feature band iPLS model, respectively. The comparative study of the models was carried out with ethanol solution as the research object and the samples were divided into two groups, including the calibration sets and the prediction sets. This study indicates that there is a certain relationship between the spectra information of the multivariate mixture and its component content, and the above two models are feasible for solving the component content. Compared with the full band PLS model, the feature band iPLS model has higher accuracy and the model is simpler. Therefore, the feature band iPLS model, which is an efficient method, can be used to analyze the component content in multivariate mixture solution based on the ultraviolet-visible spectrum.

Zinc silicates are an appealing feature for electrode materials in Li-ion battery owing to their layered structure providing a well-defined and facile Li ion transportation route. However, the poor conductivity of zinc silicates limits their wide application as electrode materials, and furthermore zinc silicates have not been explored to apply to supercapacitor. Herein, three-dimensional N, S-doped C-Zn4Si2O7(OH)2·H2O (3D C-ZnSi) have been developed by a hydrothermal process from a highly available and recyclable plant biomass – bamboo leaves, composed of organic compound and silica, for the application to supercapacitor. This is about zinc silicate first applied to supercapacitor. The as-prepared electrode materials have extensive pores inherited from biological structures of bamboo leaves, including micropores, mesopores and macropores. Owing to the existence of hierarchical pores, the single electrode presents excellent capacitance of 450 mF cm−2 at 5 mV s−1, and excellent cyclic performance with the retention of 83% after 10,000 cycles. Furthermore, the as-assembled 3D C-ZnSi//activated carbon (3D C-ZnSi//AC) flexible solid-state asymmetric supercapacitor can achieve a maximum energy density of 0.69 Wh m−2. Additionally, the device exhibits high cycle stability for 6900 cycles with the retention of 80%. This study shows the possibility for 3D N,S doped C-Zn4Si2O7(OH)2·H2O as one of the most promising candidates for high performance energy storage devices.

In this paper, nanocrystalline antimony sulfide (Sb2S3) thin films were prepared on a tin-doped indium oxide (ITO) substrate via a facile polyvinylpyrrolidone (PVP)-assisted hydrothermal method. The crystal structure, morphology and optical properties of the Sb2S3 films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV–vis spectroscopy. Well-crystallized Sb2S3 films possessed a honeycomb-like morphology with a whole thickness of approximately 360 nm on the ITO substrate and had a band gap of 2.0 eV. The reaction parameters that influenced the formation of Sb2S3 films, such as reaction time, temperature and quantity of PVP were investigated. PVP was found to play an important role in the formation of the honeycomb-like Sb2S3 films. In the absence of PVP, only large aggregates formed on the ITO substrate. A possible growth mechanism of the Sb2S3 films has been proposed. Furthermore, the as-synthesized Sb2S3 film exhibited a photocurrent density of −0.025 mA cm−2 at 0 V (vs. RHE) in a neutral solution, close to that of the heated Sb2S3 film. A stability test demonstrated that the as-synthesized Sb2S3 film was stable in both neutral and acidic solutions. This investigation might provide a feasible method for preparing high-quality Sb2S3 films to be used in solar energy conversion.

The particle swarm optimization (PSO) was introduced to calculate optical constants of liquid based on transmittance and reflectance spectrum. Two methods, namely as particle swarm double-thickness transmittance method (PTT) and particle swarm transmittance and reflectance method (PTR), were developed by combining the PSO with the spectrometry. The comparative study of two methods was carried out with distilled water as the research object, and the experimental deviation of the two methods was evaluated. The results show that the two methods are reliable for solving optical constants of liquid with high resolution accuracy, even existing experimental deviation. Meanwhile, a deviation correction method proposed in present work reduces the effect of uneven experimental deviation on the accuracy of the two methods.

The incorporation of manganese into the framework of Silicalite-1 (denoted as Mn-Silicalite-1) was achieved by the hydrothermal conversion manganese ion exchanged magadiite (Mn-magadiite) under the neutral condition. The influences of the synthetic conditions (the reaction time, the reaction temperatures and the precursors) on the synthesis of Mn-Silicalite-1 were studied in detail to reveal the successful synthesis of Mn-Silicalite-1. The introduction of the manganese into the framework of Silicalite-1 was demonstrated by the means of X-ray powder diffraction (XRD), energy-dispersive X-ray spectrometer (EDS), elemental mapping, X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis), field emission scanning electron microscopy (FE-SEM), N2 adsorption/desorption isotherms and temperature-programmed reduction (TPR). The BET surface area (SBET) and pore volume (Vp) of Mn-Silicalite-1 measured 323 m2/g and 0.052 cm3/g, respectively. All results confirmed that Mn atoms were successfully doped into the framework of Silicalite-1 and homogeneous solid-solutions of Mn-Silicalite-1 were synthesized. Furthermore, the catalytic properties of the as-synthesized Mn-Silicalite-1 were evaluated by the styrene oxidation reaction. Mn-Silicalite-1 significantly increased the active sites of the catalyst and improved the catalytic efficiency. Low temperature was beneficial to the formation of styrene oxide and high temperature was beneficial to the formation of benzaldehyde.

Intercalation and in situ formation of three fluorescent complexes, Al(III)-, Ca(II)- and Zn(II)-8-hydroxyquinoline-5-sulfonic acid (M-8HqS, M = Al, Ca and Zn) in the interlayer spaces of magadiite (mag) were synthesized by solid-solid reactions between metal ions exchanged mags (M-mag, M = Al, Ca and Zn) and 8HqS at room temperature. The intercalation and in situ formation of 8HqS molecules into the interlayer spaces of M-mags were evaluated by XRD, ICP-AES, EDS, elemental mappings, TG/DTA, elemental analysis, FE-SEM, FTIR, UV-Vis, PL and XPS. Results show that the basal spacings of the intercalated composites increase after the intercalation of 8HqS into M-mags. A new peak at 1461 cm−1 is observed, supporting the formation of the coordination complexes between 8HqS and metal cations. The slight shift of the absorption and luminescence bands of the complexes suggests the different microstructures including molecular packing of the complexes in the interlayer spaces of mags, which indicating that the process is a host-guest interaction. The amount of 8HqS in the intercalated compounds is different due to the diversification of coordination ability of metal ions, and the order of the coordination ability of these three metal ions is Ca2+ > Zn2+ > Al3+. The amount of the metal cations (Al3+, Ca2+ and Zn2+) in the interlayer of mag is enough for the in situ complex formation of M-8HqS complexes. Thus, the intercalation and in situ formation of M-8HqS complexes (M = Al, Ca and Zn) in the interlayer space of mag are successfully achieved in the present work.

Three-dimensional (3D) porous N, O-doped carbon with hierarchical structures composed of micropores, mesopores and macropores were synthesized by the direct carbonization of kelp with a “self-activation” process. The as-obtained 3D N, O-doped carbon remained abundant N and O functional groups and the BET specific surface area measured 656 m2 g−1. 3D hierarchical porous structures with the pore size ranged from several nanometers to hundred nanometers and lots of pores were attributed to mesopores with the average pore size of about 5.4 nm. Electrochemical properties of the 3D hierarchical porous N, O-doped carbon as a supercapactior (SC) electrode were investigated and it delivered excellent capacitance of 669 mF cm−2 at 1 mA cm−2 due to its 3D hierarchical porous structures with high specific surface area which is beneficial for improving ionic storage and transportation in electrodes. This kelp-derived carbon exhibited excellent cyclic performance with the retention of 104% after 10,000 cycles. A flexible solid-state symmetric SC (SSC) device was fabricated using the 3D hierarchical porous N, O-doped carbon and delivered an excellent capacitance of 412 mF cm−2 at 2 mA cm−2 and satisfying cyclic stability with the retention of 85% after 10,000 cycles. The areal energy density of the SSC device reach up to 0.146 mWh cm−2 at the power density of 0.8 mW cm−2. This facile route for low-cost carbonaceous materials with novel architecture and functionality can be as a promising alternative to synthesize biomass carbon for practical SC application.

Amorphous manganese silicate/multi-walled carbon nanotubes (AMSi/MWCNTs) composites were successfully synthesized using MWCNTs, manganese dichloride and sodium silicate as the starting materials by a facile precipitation method. The composition and morphology were characterized by X-ray powder diffraction, energy-dispersive X-ray spectrometer, elemental mapping, Raman, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. Electrochemical properties of AMSi/MWCNTs as supercapacitor electrode were studied. It was found that the electrochemical performance of AMSi could be adjusted by the amount of MWCNTs. Specific capacitance of AMSi/MWCNTs reached the highest value (236 F g−1 at 0.5 A g−1) in the presence of 40 wt.% of MWCNTs. Asymmetric supercapacitor device assembled from AMSi/MWCNTs and activated carbon (AMSi/MWCNTs//AC) showed its specific capacitances reached 146, 139, 119, 108 and 99 F g−1 at current densities of 0.5, 1, 2, 5 and 10 A g−1, respectively. A capacitance retention of 81% for AMSi/MWCNTs//AC device after 1000 cycles indicated that AMSi/MWCNTs had good cycling performance applied to SC device. Present findings demonstrated that MWCNTs could improve the electrochemical properties of AMSi and suggested that AMSi/MWCNTs composites could be considered as potential materials for high-performance energy storage device.

Hybrids consisting of mesoporous carbon and uniform sized, regular morphology and even distributed metal silicate have been a challenge, although they are a potential promising material for electrochemical supercapacitor. In this work, we have synthesized a hybridized supercapacitor electrode of layered nickel silicate Ni3Si2O5(OH)4 nanoparticles on the porous carbon derived from calcined natural bamboo leaves (C-SiO2). The good combination of C-SiO2 and in situ generated layered nickel silicate, which turned out to be an outstanding electrode, demonstrates high specific surface area, multiporous structure, good electrical conductivity, and prominent electrochemical performance. For instance, the obtained C-NiSi-3 showed 132.4 F g–1 at a current density of 0.5 A g–1 and significantly maintained 100% after 10000 cycles. Furthermore, a flexible all-solid-state asymmetric supercapacitor device was assembled by C-NiSi-3 and Ni(OH)2. The device was suited to various bending angles and achieved a high capacitan...

V2O3@C core-shell nanorods with porous structures and large specific surface area were synthesized using V2O5 nanowires as the source of core and glucose as the source of shell by a facile hydrothermal route combination of heat treatment. As-prepared V2O3@C nanorods comprised of core-shell structures with crystalline V2O3 cores and amorphous carbon shells. Nitrogen adsorption-desorption isotherms revealed that V2O3@C core-shell nanorods displayed BET specific surface area as high as 219 m2·g−1 and had hierarchical porous structures. Electrochemical properties of V2O3@C core-shell nanorods as supercapacitor electrode were studied and showed their measured capacitance was based on the pseudocapacitance. Specific capacitances of V2O3@C core-shell nanorods measured 228, 221, 207, 158 and 127 F·g−1 at current densities of 0.5, 1, 2, 5 and 10 A·g−1, respectively. Results showed V2O3@C core-shell nanorods displayed higher specific capacitance than values of carbon spheres (4 F·g−1 at 1 A·g−1) and V2O3 nanomaterials (49 F·g−1 at 1 A·g−1). Asymmetric supercapacitor device assembled from V2O3@C core-shell nanorods and activated carbon (V2O3@C//C) showed specific capacitances of 0.297, 0.274, 0.230, 0.194 and 0.169 F·cm−2 at current densities of 0.5, 1, 2, 5 and 10 mA·cm−2, respectively. It showed higher specific capacitance than that of V2O3//C device (0.219 F·cm−2 at 1 mA·cm−2). A capacitance retention of 86% for V2O3@C//C device after 1000 cycles indicated that V2O3@C had good cycling performance for supercapacitor application. Present findings suggested that V2O3@C core-shell nanorods could be considered as potential materials for high-performance energy storage materials.

The present work is to experimentally investigate the optical properties of liquid paraffin contained with Al2O3 nanoparticles for application in glazed envelope. Paraffin-based Al2O3 nanofluids were prepared through two-step method and its transmittance spectrum was measured by a TU-19 FTIR spectrometer. Based on the optical properties of liquid paraffin contained with Al2O3 nanoparticles obtained by model calculation, the changes of optical properties of liquid paraffin filled with and without Al2O3 nanoparticles are compared. The results show that compared with pure paraffin, the presence of Al2O3 nanoparticles decreases the transmittance of liquid paraffin by 15.7% in 5 mm optical path when the concentration is 0.001 vol%, and the nanofluids absorption coefficient is about 20.07 m−1 in the visible spectrum, which is almost 4 times that of pure paraffin. Meanwhile, the addition of Al2O3 nanoparticles makes the reflectivity of paraffin increase by 0.022. This conclusion is useful in analyzing glazed envelope contained Al2O3/paraffin nanofluids and provides a method of solar energy harvesting.

Semiconductor heterostructures are regarded as an efficient way to improve the photocatalytic activity. Herein, novel Z-scheme CaIn2S4 (CIS)/TiO2 heterostructures photocatalysts were synthesized by a simple two-step hydrothermal approach. Compared with single phase nanostructures of TiO2 and CIS, the CIS/TiO2-0.05 g nanocomposites exhibited efficient and stable photocatalytic activity, with 97% of methyl orange (MO) decomposed within 30 min under UV–visible light irradiation. In addition to increased broad light absorption, the outstanding photocatalytic performance is mainly attributed to intimate contact and matched energy band positions between CIS and TiO2, which efficiently produce more active electrons and holes, reduce the photogenerated electron-hole recombination, and boost photoinduced charge carrier transfer. The possible Z-scheme mechanism for the photocatalytic reaction in the system was reasonably proposed. This work would arouse an increasing interest in designing more Z-scheme heterojunction photocatalysts with high efficiency for the application of photodegradation.

A series of room temperature ferromagnetic (RTFM) Al1-xScxN nanowires with Sc-dopant concentration x ranging from 0 to 4.7% were prepared by the direct reaction of different weight ratios of Al:Sc alloy with N2 gas using plasma assisted direct current (DC) arc discharge method. Powder X-ray diffraction (XRD) and Raman scattering spectra revealed that Sc incorporates into the AlN crystal lattice. With the increase of the Sc content, the wurtzite-structure AlN maintained with increasing volume of unit cell even when the Sc content reached 4.7 at.%, meanwhile, the Sc dopant concentration reached saturation, indicating the successful incorporation of Sc ions into AlN lattice. Scanning and transmission electron microscopy measurements show that the nanowires have uniform diameters of about 50–100 nm and are several tens of microns in length. Magnetic measurements revealed that the room temperature ferromagnetism increased with the increase of Sc dopant concentration and the ferromagnetism remained unchanged when the Sc content reached saturation.

Tb doped AlN (AlN:Tb) nanobelts were prepared by in situ doping of Tb using a plasma-assisted arc discharge method. The structure, composition and morphology of the doped nanobelts were studied by means of X-ray diffraction, scanning and transmission electron microscopy and X-ray photoelectron spectroscopy, revealing that Tb ions have been introduced into the lattice of wurtzite-structured AlN nanobelts. The AlN:Tb nanobelts exhibit distinct emission peaks corresponding to intra-4f electron transitions of Tb3+ ions, and room temperature ferromagnetism, which make AlN:Tb nanobelts an excellent candidate for applications in future solid light-emitting diodes and spintronic nanodevices.

SiO 2 nano-network structures have been synthesized by a simple thermal evaporation process in a large scale using S and SiO 2 as the source materials without the use of any metal catalysts at a relatively low temperature. The detailed structural characterization indicated that the obtained SiO 2 nano-networks are composed of small nanoparticles with the size of about 10 nm with a monoclinic structure and a small amount of Si nanocrystals synthesized in the fabrication process of SiO 2 nano-network structures. Room-temperature photoluminescence (PL) and UV–Vis absorption spectrum of the grown products indicate unique optical properties. Different from the traditional normal SiO 2 nanomaterials, due to the quantum confinement effects of embedded Si nanocrystals, the SiO 2 nano-networks show a wider light emitting area extending above 700 nm.

Natural fiber-reinforced polymer matrix composites have been increasingly used in automotive and other fields because of their good mechanical properties, low density, excellent damping properties ...

(NH4)2V3O8/carbon composites were successfully achieved using NH4VO3 and glucose as the starting materials via a one-step hydrothermal route for the first time. The composites consisted a layer structured (NH4)2V3O8 and amorphous carbon with aromatic structures containing lots of active function groups. Then porous V2O5 nanoparticles were fabricated by the thermal treatment of (NH4)2V3O8/carbon composites in air atmospheres. The BET specific surface area of (NH4)2V3O8/carbon composites measured 1.68 m2 g−1, whereas BET surface area of porous V2O5 nanoparticles reached 10.6 m2 g−1 and the average pore size totaled 28.9 nm. The synthetic process of (NH4)2V3O8/carbon composites and porous V2O5 nanoparticles was briefly discussed. Electrochemical properties of porous V2O5 nanoparticles as supercapacitor electrodes were investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) both in the aqueous and organic electrolytes. The influence of calcined temperature and time and the mole ratio of NH4VO3/glucose on specific capacitance, phase and morphology of samples were discussed in detail. Porous V2O5 nanoparticles respectively exhibited the specific capacitance of 433 and 545 F g−1 in the aqueous and organic electrolytes at the current density of 1 A g−1. After 100 cycles, the capacitance retention was 89.6% in organic electrolyte, whereas it was only 22.9% in aqueous electrolyte. It turned out that electrochemical properties of porous V2O5 nanoparticles were greatly improved by using organic electrolyte.

Hierarchical porous vanadyl hydroxide (VOOH) hollow spheres were successfully prepared using ammonium metavanadate as starting vanadium source materials through a facile hydrothermal method. Their morphology, structure and composition were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, energy-dispersive X-ray spectrometry, elemental mapping, elemental analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and nitrogen adsorption-desorption isotherms. Brunauer-Emmett-Teller specific surface area of hierarchical VOOH hollow spheres measured 32 m 2 g −1 , and their most probable distribution pore size reached 3.6 nm. Results demonstrated that hierarchical VOOH hollow spheres possessed macropores in their hollow interior and mesopores in shell. Electrochemical properties of hierarchical VOOH hollow spheres as supercapacitor (SC) electrodes were explored and investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. Results showed that hierarchical VOOH hollow spheres featured capacitive behavior based on pseudocapacitance, and exhibited specific capacitance of 93 F g −1 at current density of 0.2 A g −1 . Cycling stability was discussed in detail and indicated good rate capability of studied materials. VOOH hollow spheres are ideal material for SC electrodes in the present study.

Transmittance spe ctrum of ZnSe in the infrared and visible wavelength range at normal incidence was investigated by an IRTracer-100 spectrometer and a TU-19 Double-Beam Visible spectrophotometer, and the optical constants of ZnSe were obtained based on modelling transmittances of two ZnSe slabs. The results show that the transmittance values of the ZnSe slabs are higher than 0.7 in the wavelength range of 2.5–15 μm; however they decrease dramatically when the wavelength is larger than 15 μm. The refractive index of ZnSe varies within 2.6–2.8 in the wavelength range of 0.55–0.85 μm and 2.2–2.4 in the wavelength range of 2.5–20 μm. The extinction coeffi cient of ZnSe varies within 10–8–10–6 in the wavelength range of 0.55–0.85 μm and 10–5–10–4 in the wavelength range of 2.5–20 μm.