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Metal phosphorus trichalcogenides (MPX3) have attracted extensive attention as promising two-dimensional (2D) layered materials in future electronic and optoelectronic devices. Here, for the first time, few-layer In4/3P2Se6 nanoflakes have been successfully exfoliated from home-made high-quality single crystals. The In4/3P2Se6 crystal belongs to the R3 space group, and possesses a weak van der Waals force between the adjacent layers and a direct bandgap of 1.99 eV. Furthermore, the In4/3P2Se6-based photodetectors show high performances in the visible light region, such as a high responsivity (R) of 4.93 A·W-1, a high external quantum efficiency (EQE) of 1509% and a fast response time, as low as 2.1 ms. In particular, the high detectivity (D) of the devices can reach up to 4.3 × 1013 Jones (light ON/OFF ratio ≈104) under illumination from a 405 nm light at a bias voltage of 1 V, which is favoured by the ultralow dark current (∼100 fA). These excellent performances pave the way for the implementation of In4/3P2Se6 nanoflakes as promising candidates for future optoelectronic detection applications.

Metal phosphorus trichalcogenides (MPX

Dragonflies are excellent flyers among insects and their flight ability is closely related to the architecture and material properties of their wings. The veins are main structure components of a dragonfly wing, which are found to be connected by resilin with high elasticity at some joints. A three-dimensional (3D) finite element model of dragonfly wing considering the soft vein joints is developed, with some simplifications. Passive deformation under aerodynamic loads and active flapping motion of the wing are both studied. The functions of soft vein joints in dragonfly flight are concluded. In passive deformation, the chordwise flexibility is improved by soft vein joints and the wing is cambered under loads, increasing the action area with air. In active flapping, the wing rigidity in spanwise direction is maintained to achieve the required amplitude. As a result, both the passive deformation and the active control of flapping work well in dragonfly flight. The present study may also inspire the design of biomimetic Flapping Micro Air Vehicles (FMAVs).

Lignin is a superb renewable feedstock for deriving petroleum-analogous biochemicals and value-added bioproducts. However, proper elucidation of its original biosynthetic structure and subsequent deconstruction is necessary to facilitate proper exploitation. Herein, its chemical substructure and linkages within an important global feedstock, rice straw, were interrogated by spectroscopy. Pyrolysis was chosen to cleave it and obtain guaiacyl (G), syringyl (S), and hydroxyphenyl (H) monophenols distributions at various temperatures. A unique relationship between product substructures and lignin depolymerization was revealed. The overall scope of the depolymerization mechanism into monophenols by cleavage of β-O-4 and β-5 in phenylcoumaran subunits were explored experimentally and through bond dissociation energy (BDE) theory.

Undesirable side reactions at interface usually ruin the electrode stability and lead to serious self-discharge or decrease the coulombic efficiency. An ionic permeable and electronic insulating amorphous TiO2 passivation could be deposited on the carbon encapsulated LiTi2(PO4)3 electrode through sol-gel method, which drastically enhance the aqueous electrode stability and oxygen tolerance in wide potential window by kinetically suppressing the side reactions at new formed interface. Raman depth profile and SEM have confirmed this surface coating, while nanoelectronic conductivity analysis reveal the TiO2 layer is electronically insulate. The capacity retention of the TiO2 passivated carbon encapsulated LiTi2(PO4)3/LiNO3/LiMn2O4 coin cell for 2000 cycles is 66% assembled in ambient air, which is higher than 55% for the one without TiO2 coating. Electrochemical investigation suggests the TiO2 layer is Li+ ionic conductive, which suppressed the surface water reduction or oxygen reduction reaction. As an interestingly result, the cell stability improvement also benefited from the less degradation of the LiMn2O4 counter electrode. This comprehensive understanding of the electrode passivation using an ionic conductive layer can be potentially applied in other electrochemical devices.

Exploring novel hybrid materials with efficient microstructure using facile approaches is highly urgent in designing supercapacitor electrodes. Here, the Ni-B membrane was used for coating the porous Co 3 O 4 nanoneedle arrays which supported on the nickel foam (NF) frameworks through a rapid chemical reduction process (denoted as NF/Co 3 O 4 @NiB). The Ni-B membrane both provided sufficient active sites for redox reactions and inhibited the aggregation of formed hybrid architectures. Benefiting from the unique structural design and strongly coupled effects between porous Co 3 O 4 arrays and Ni-B membrane, the resulted NF/Co 3 O 4 @NiB electrode exhibited high areal capacitance of 3.47 F cm −2 (0.48 mAh cm −2 ) at a current density of 2.5 mA cm −2 , an excellent rate capability while maintaining 95.5% capacity retention after 2000 cycles. The asymmetric supercapacitor constructed with the NF/Co 3 O 4 @NiB as positive electrode and hierarchical porous carbon (HPC) as negative electrode also showed ideal capacitive behavior, and simultaneously delivered high energy and power densities. The easily decoration of Ni-B membrane on various active nanoarrays may arouse more novel design about hybrid architectures for large-scale applications.

Nano sized copper oxide was firstly employed for producing Jun-red glazes. A series of Jun-red glazes were prepared by adjusting the copper oxide nanoparticle content and the valance state of elemental copper in the glaze matrix. The coloring and microstructure of each glaze was investigated by spectrophotometer, XRD, SEM, XPS and TEM. Under reducing conditions, the red glaze color gradually darkens with increasing CuO content from 0.5 to 1.0 wt %. Interestingly, the coloring of the samples fired under reducing atmosphere turned to be green-blue, when the content of nanosized CuO was increased to 1.5 wt %. We also found that increased CuO content increases the size of phase separation in the glazes. As comparison, the coloring of samples fired without nanosized CuO are slightly blue under reducing atmosphere, which is attributed to the structural color generated owing to the Rayleigh scattering. Red color of the Jun glazes may arise from elemental copper nanoparticles. The current research utilizing modern nanotechnology provides a new insight into both the “furnace transmutation” and “color regulating” of the ancient Jun-red glazes. This article is protected by copyright. All rights reserved.

Fe3O4@SiO2-SO3H nanocomposites were successfully synthesised as the efficient magnetically separable solid acid catalysts for an esterification reaction. The resultant catalysts were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, vibrating sample magnetometer (VSM), and nitrogen physical adsorption analyses [Brunauer–Emmett–Teller (BET) theory]. The catalytic activities of as-prepared Fe3O4@SiO2-SO3H nanocomposites were also investigated for the esterification of n-butyl acetate and isoamyl acetate. The acid esterification rate was confirmed by gas chromatography. The results showed that the Fe3O4@SiO2-SO3H nanocomposites can be as candidate cataysts for the concentrated H2SO4 for the esterification reaction of n-butyl alcohol or isoamyl alcohol. More importantly, the magnetic catalysts can be easily separated from the reaction system by a magnetic bar and reused at least three recycles without significant degradation of their activities.

Two-dimensional In2Se3 crystal is a promising candidate for optoelectronics, phase-change memories and ferroelectrics. However, due to its polymorphic crystal structures, the controlled growth of pure monophasic In2Se3 poses a huge challenge for the fundamental physical exploration and practical applications. Here, we demonstrate a substrate-directed method to prepare β- and γ-phase In2Se3 thin films on Al-doped ZnO (AZO) and F-doped SnO2 (FTO) substrates, respectively. Aliovalent ion dopant with Zn element is responsible for stabilizing the metastable β-In2Se3. Owing to its narrow bandgap, the β-In2Se3 photodetector exhibits a wide spectral photoresponse. In addition, the as-grown layered β-In2Se3 thin films can be exfoliated to few atomic layers and exhibit n-type behavior. This work demonstrates that directed phase-engineering on different substrates may be an important breakthrough towards large-scale preparation of the desired phase In2Se3 atomic crystals.

An innovative molten-salt method is presented for the in-situ reactive preparation of surface-modified diamond particles. Surface-modified diamond particle reinforced metal-based (copper or magnesium) composites were prepared by spark plasma sintering. Field-emission scanning electron microscopy was used to analyze the surface morphologies of the surface-modified diamond samples and the interfacial bonding of the diamond-metal composite materials. The elemental distributions of the surface-modified diamond particles were analyzed by energy-dispersive X-ray spectroscopy, and X-ray diffraction was used to analyze the phase compositions of the samples. By means of X-ray photoelectron spectroscopy and laser Raman spectroscopy, the surface bonding and graphitization of the surface-modified diamond particles were further analyzed. The results showed that the thickness of the modification layer on the surface of diamond increased gradually with increasing holding time. The surface-modified diamond particle reinforced metal-based composite materials had high thermal conductivities. When the volume percentage of diamond was 35%, the thermal conductivities of the diamond–copper composites were as high as 602 W·m−1·K−1, and the thermal conductivity of the diamond–magnesium composites reached 286 W·m−1·K−1.

Flexible photodetectors based on two-dimensional (2D) materials hold the promise to open up an unprecedented era for wearable optoelectronic systems. However, there is a major challenge of the inability to directly deposit 2D materials on polymeric substrates due to their high growth temperature. Here, we demonstrate a novel low-cost method to directly fabricate SnS nanoflakes on the poly-ethylene terephthalate substrates. Moreover, the flexible photodetectors based on SnS nanoflakes feature broadband spectral responses from 355 nm to 1550 nm. The responsivity and detectivity can approach up to 1.28 × 103 A W−1 and 3.02 × 1011 Jones, respectively, under the ultraviolet laser of 355 nm. The devices also exhibit excellent NIR photodetection with a specific responsivity of 69 A W−1 towards the 1550 nm regime. Our research represents an important step toward scalable fabrication of the SnS nanoflakes and this method may pave a path for the future commercialization of flexible broadband optoelectronic devices.

To acquire a well bonded interface between the copper and the diamond particles in diamond-copper matrix composites, an available process to apply a vapor deposited aluminum (Al) coating onto diamond particles was used to solve this interfacial problem. The diamond-copper matrix composites were prepared by spark plasma sintering (SPS) process and the effect of Al-coated diamond particles was demonstrated. The experimental results showed that the densification, interfacial bonding and thermal conductivity of Al-coated composites were evidently improved compared to those of the uncoated composites. A maximum thermal conductivity (TC) of 565 W/(m·K) was obtained in the coated composite containing 50vol% diamond particles sintered at 1 163 K. Additionally, the experimental data of thermal conductivity and coefficient of thermal expansion (CTE) were compared with the predictions from several theoretical models.

Cu6Sn5 intermetallic nanoparticles have been successfully prepared by a simple reduction method. The crystallinity and morphology of the synthesized products were characterized by means of X-ray diffraction and scanning electron microscopy, respectively. When used as anode material, Cu6Sn5 intermetallic nanoparticles demonstrated an initial discharge capacity of 3368.2 mAh · g−1 and stable capacities of 840 mAh · g−1 after 70 cycles between 0.05 and 2.5 V at a current density of 100 mA · g−1. The charge–discharge process of Cu6Sn5 intermetallic nanoparticles was also evaluated using cyclic voltammetry. The results indicated Cu6Sn5 intermetallic nanoparticles may be an ideal anode material for Li ion batteries.

Walnut-like CoS2 hierarchical structures were synthesised by a simple hydrothermal method. The crystalline phase and morphology of the products were characterised with X-ray diffraction and scanning electron microscope, respectively. The results showed that CoS2 prepared by hydrothermal method were hierarchical walnut-like materials consist of nanoparticles. As an anode material of Li ion batteries (LIBs), reversible capacity of these CoS2 materials reached 132.8 mAh/g after 100 cycles. Due to outstanding electrochemical performance, CoS2 materials can be exploited as a practical anode material for LIBs.

An innovative method of in-situ reactive preparation of diamond/silicon(Ti) matrix composites by spark plasma sintering (SPS) process was applied to produce specimens and the effect of Ti-addition to Si matrix was demonstrated. The relative density of diamond/Si(Ti) matrix composite was >98.1% in a volume fraction of diamond ranging from 40% to 60%. Actually, Si(Ti)/diamond composites containing 60% in volume diamond particles yielded a thermal conductivity (TC) of 525 W m−1 K−1 at room temperature along with a thermal expansion coefficient (TEC) of 1.643×10−6 K−1 at 573 K. TC and TEC of the experimental data were compared with the predictions from several theoretical models. Microstructures of these materials were studied by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Ti addition lowered the melting point and resulted in the formation of TiSi2 phase in Si matrix. The results show that Ti addition is an effective approach for promoting the relative packing density and improving thermal conductivity of sintered samples.

ZnO micro/nano structures with different morphologies have been prepared by the changing solvents used during their synthesis by solvothermal reaction. Three typical shapes of ZnO structures including hexagonal, bell bottom like and multi-pod formed and were characterized by scanning electron microscopy and X-ray diffraction. Multi pod like ZnO structures exhibited the highest photocatalytic activity toward degradation of methyl orange. Using electron spin resonance spectroscopy coupled with spin trapping techniques, we demonstrate an effective way to identify precisely the generation of hydroxyl radicals, superoxide and singlet oxygen from the irradiated ZnO multi pod structures. The type of reactive oxygen species formed was predictable from the band gap structure of ZnO. These results indicate that the shape of micro-nano structures significantly affects the photocatalytic activity of ZnO, and demonstrate the value of electron spin resonance spectroscopy for characterizing the type of reactive oxygen species formed during photoexcitation of semiconductors.

Constructing van der Waals (vdW) heterostructures with various-layered two-dimensional (2D) materials is attractive to design various materials and devices. For controllable fabrication of vdW heterostructures, it is very important to make the growth process clear. In this work, SnS2/MoS2 vertical heterostructures were synthesized by the one-step chemical vapor deposition (CVD) method. The bottom MoS2 triangle layers can be partially or completely covered by SnS2 layers. The interlayer charge separation was also observed in the heterostructures by photoluminescence (PL) spectroscopy. The growth mechanism of SnS2/MoS2 vertical heterostructures was also discussed for the first time. MoS2 triangle layers form on the substrates at first and then grow a top layer of SnS2. This study will provide an important and practical method, as a guidance to prepare high-quality vertical heterostructures.

We present a facile, non-injection synthesis of high quality CZTS nanocrystals by using simple inorganic salts, sulfur powders and (CH3)3COK (KTB) as precursors. The uniqueness and creativity is the utilization of KTB as sulfur activating agent and stabilizing surfactant agent.

In this paper, Pt-Co3O4 nanocomposite was synthesized by a sol-gel process combined with electrodeposition method. Its electrocatalytic activity towards methanol oxidation was investigated at room temperature using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and current density-time curve. It is found that the resultant Pt-Co3O4 catalysts with minute amount of Pt exhibite attractive electrocatalytic activity for methanol oxidation reaction (MOR) but with a high resistance CO poisoning due to the synergistic effects from Pt and Co3O4. Together with the low manufacturing cost of Co3O4, the reported nanostructured Pt-Co3O4 catalyst is expected to be a promising electrode material for direct methanol fuel cells (DMFC).

In this paper, we described how WO3 microspheres have been synthesized by a simple hydrothermal treatment from the precursor of Na2WO4 and CO (NH2)2 at 160 °C for 3 h. The sample was characterized by X-ray diffraction (XRD), energy dispersive spectrum (EDS), scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), high resolution transmission electronic microscopy (HRTEM), selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS). Obtained results indicated that the average diameter of the as-prepared WO3 microspheres is ∼1 μm with orthorhombic phase. The WO3 microspheres are constructed of polycrystalline WO3 nanoparticles. The thickness of the WO3 coating of the gas sensor is ∼2 μm. The WO3-based gas sensor exhibited a good sensitivity and high selectivity to acetone vapor at 200 °C. A possible mechanism for the acetone vapor gas sensing was proposed.

Graphical abstract: - Highlights: • Cu{sub 2}S thin films with hierarchical nanostructures have been synthesized by solvothermal method using DMSO as reactant. • The band gap is estimated to be 1.0 eV of the Cu{sub 2}S hierarchical nanostructures. • The form process of Cu{sub 2}S and the possible mechanism of hierarchical nanostructures were proposed. - Abstract: In this paper, Cu{sub 2}S thin film with hierarchical petal-like nanostructures has been successfully in situ synthesized via a solvothermal method using DMSO as reactant under appropriate reaction conditions. The crystalline phase, morphology and optical properties of the resulting products were characterized by X-ray diffraction, energy-dispersive X-ray spectrometry, scanning electron microscopy and UV–vis absorption spectroscopy, respectively. The band gap is estimated to be about 1.0 eV by the results of UV–vis absorption spectroscopy of the Cu{sub 2}S thin film with hierarchical nanostructures that consisted of nanoslices with the thickness of 15 nm. The formation process of Cu{sub 2}S and the possible mechanism of hierarchical nanostructures were also proposed. These findings are valuable since Cu{sub 2}S thin film with hierarchical petal-like nanostructures are promising candidate as lithium ion battery and solar cell materials.

Copper selenide films with different phase and morphology were synthesized on copper substrate through controlling reaction solvent by microwave-assisted nonaqueous approach. The films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The result showed that the pure films could be obtained using cyclohexyl alcohol or benzyl alcohol as solvent. The cubic Cu 2− x Se dendrites were synthesized in cyclohexyl alcohol reaction system and hexagonal CuSe flaky crystals were obtained with benzyl alcohol as solvent.

In this work, MFe2O4 (M = Zn, Cu) nanoparticles were successfully prepared by a hydrothermal method. The structure, morphology, microstructure, specific surface area and electrochemical properties ...

A new series of ternary semiconductor compounds, Cu7.2(SexS1−x)4 (0.2 ≤ x ≤ 0.8) nanocrystallites, that exhibited good photocatalytic activity under visible-light irradiation, were facilely synthesized under mild conditions. The Cu7.2(SexS1−x)4 nanocrystallites were characterized by powder X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy and UV-Vis absorption spectra. From X-ray data it is found that the cell constant a of different samples varies linearly with the composition x as: a (A) = 5.5959 + 0.1586x. UV-Vis absorption spectra indicate that the apparent band gap energies can be tuned by adjusting the composition x so as to better match to the whole solar spectrum. Unlike the most studied TiO2 that only responds to the UV-light irradiation, the present Cu7.2(SexS1−x)4 nanocrystallites exhibited much better photocatalytic activity under visible light on degradation of RhB. It is believed that the photocatalytic superiority of the Cu7.2(SexS1−x)4 nanocrystallites is mainly due to the compositional gradient arisen from uneven distribution of Se/S compositions in the compounds, which may induce a more efficient charge separation/transport in the Cu7.2(SexS1−x)4 photocatalysts.

SnSe2/Se heterojunction films were successfully grown on fluorine-doped tin oxide (FTO) glass for the first time via a one-step solvothermal route using magnetron sputtered Sn metallic precursors, Se powders as selenium source, cyclohexanol as solvent and cyclohexanol as auxiliary solvent, respectively. The SnSe2/Se heterojunction films consisted of Se nanoparticles or nanorods cluster and SnSe2 network surface layers. The crystalline phase and morphology of SnSe2/Se films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), respectively. The photocatalysis measurements of the products for rhodamine Blue (RhB) demonstrated that SnSe2/Se heterojunction films revealed better dye degradation properties than SnSe2 nanosheet films due to the higher separation rates of photogenerated electron–hole pairs of SnSe2/Se heterojunction films, which can be confirmed by surface transient photovoltage (TPV) analyzer.

In this paper, we report on a nonaqueous synthesis of single crystalline anatase TiO2 nanorods by reaction between TiCl4 and benzyl alcohol at a low temperature of 80 °C. The resulting samples were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, nitrogen adsorption, X-ray photoelectron spectrometry and UV–vis diffuse reflectance spectroscopy. We proposed that the TiO2 nanorods were formed through an oriented attachment mechanism. More importantly, these single crystalline anatase TiO2 nanorods exhibited significantly higher photocatalytic activities than commercial photocatalyst P25. This study provides an environmentally friendly and economic approach to produce highly active TiO2 photocatalyst.

Thin films of metal iodides (e.g., CuI, AgI and PbI2) were rapidly synthesized by a sonochemical method. For example, perfect CuI crystals with uniform polyhedral structures could be formed directly on copper foils with the irradiation time as short as 10 s via interfacial reaction between copper foils and elemental iodine in ethanol at ambient temperature. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectra (PL). A probable mechanism was proposed to explain the rapid growth of CuI crystals. This facile approach could also be used to grow other metal iodides such as AgI and PbI2 nanocrystals. It was found experimentally that the resultant metal iodide films could better resist spinning under the drastic ultrasound irradiations in a liquid media. Particularly, the resulting CuI films showed strong, room temperature PL emissions at the energy around their band gaps. This method is believed to be the fastest way for in-situ fabrication of semiconductor films on various metal substrates for subsequent applications related to the metal iodide semiconductor films.

A facile solution-phase chemical route is developed to directly construct silver iodide (AgI) films/crystals on various substrates including silver foil, silicon wafer and glass, etc. The resulting AgI films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The AgI films with different morphologies can be obtained by controlling the reaction parameters. This method is a simple and fast way for in situ deposition of AgI crystals/films on different substrates. These films may be applied in chemical sensing systems and solid-state batteries as solid electrolytes.

Nano-sized nickel ferrite (NiFe2O4) was prepared by hydrothermal method at low temperature. The crystalline phase, morphology and specific surface area (BET) of the resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and nitrogen physical adsorption, respectively. The particle sizes of the resulting NiFe2O4 samples were in the range of 5–15 nm. The electrochemical performance of NiFe2O4 nanoparticles as the anodic material in lithium ion batteries was tested. It was found that the first discharge capacity of the anode made from NiFe2O4 nanoparticles could reach a very high value of 1314 mAh g−1, while the discharge capacity decreased to 790.8 mAh g−1 and 709.0 mAh g−1 at a current density of 0.2 mA cm−2 after 2 and 3 cycles, respectively. The BET surface area is up to 111.4 m2 g−1. The reaction mechanism between lithium and nickel ferrite was also discussed based on the results of cycle voltammetry (CV) experiments. Keywords: NiFe2O4, Anode materials, Lithium ion battery, Electrochemical properties, Hydrothermal

In this paper, lead iodide and lead oxide iodide crystalline films/crystals with various micro/nano-morphologies were synthesized by taking advantage of simple hydrothermal/solvothermal reactions between lead foil and element iodine under different conditions. The resulting products were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). It was found that the morphologies of the resulting thin films/crystals could be well controlled by the adjustment of several parameters including iodine concentration, reaction time, temperature and reaction solvents. Possible growth mechanisms of the lead iodide crystalline compounds were also discussed. The present research work may provide new insights into the morphology-controlled synthesis of metal iodide as well as other inorganic materials.

In this study, a novel method was used to prepare well-separated and spherical tricobalt tetraoxide (Co3O4) nanosized particles. The overall process involves three steps: preparation of insoluble carboxyl-containing grafted starch copolymer (ISC), formation of precursor (ISC-Co), decomposition of ISC-Co, and phase transition of Co3O4 nanoparticles. The Infrared spectra used for ISC and ISC-Co are discussed. The decomposition of the precursor was studied by thermogravimetric-differential thermal analysis, the crystalline phase was characterized by x-ray diffraction, and the size distribution and shape of particles were observed by transmission electron microscopy.

A new mechanism to generate the torque of flapping dragonfly wings is disclosed in this paper. The concept is inspired by blood circulation in insect wings. The blood flowing in veins induces Coriolis forces in the flapping wings. The Coriolis forces acting on veins are of opposite directions when blood flows in and out. The opposite Coriolis forces generate torsional moment to the wing, especially in the leading-edge part. To estimate the time-varying torque induced by the blood circulation, a simplified U-tube model is designed. A three-dimensional finite element model of the wing is developed to analyze the dynamic behaviors under this torque. The dragonfly wing is in favor of torsional deformation because the corrugated structure is of high flexural rigidity in the spanwise direction but is of low torsional rigidity in the chordwise direction. In both the downstroke and upstroke, the twist of the leading-edge part causes the sections to camber spontaneously. Such a kind of deformation is found to be of great importance to improve aerodynamic efficiency. In addition, it also compensates for the disadvantageous bending deformation caused by air pressure in flapping flight. These results are important for better understanding of the multifunctional structures of dragonfly wings and may give some inspiration to the bionics of flapping-wing micro air vehicles (FMAVs).

The surfaces of the veins of dragonflies (Pantala flavesens Fabricius and Crocothemis servilia Drury) wings are observed through SEM, and interesting micro and nano structures and morphologies are discovered. On the surfaces of the veins, not only ripple wave morphologies are distributed, but also spikes are grown. Besides, on the surfaces of the spikes, straight stripe wave morphologies are grown along the generatrix. These marvelous micro and nano structures and morphologies may enable us to better understand the remarkable flying abilities of dragonflies.

Copper selenide films with different structure and morphology are deposited on Cu foils using Se powder in Cy-OH or Ph-CH2-OH (microwaves, 160 °C, 10 min).

CuS nanofilms were prepared by a facile two-step process including chemical bath deposition of Cu nanofilms first and the subsequent thermal sulfuration step. The composition and structure of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. The optical properties of CuS nanofilms were determined by Ultraviolet-visible (UV-Vis) technique. The results show that the nanofilms composed by Cu spherical nanoparticles were completely transformed to the nanofilms composed by CuS nanosheets when the sulfuration temperature was 350[Formula: see text]C. The light absorption edges of CuS nanofilms exhibit red shift when sulfuration occurred at lower temperature. A plausible growth mechanism related with gas phase reaction for formation of CuS nanofilms was also proposed.

The assembly modes of dragonfly wings are observed through FEG-ESEM. Different from airplane wings, dragonfly wings are found to be assembled through smooth transition mode and global package mode. First, at the vein/membrane conjunctive site, the membrane is divided into upper and lower portions from the center layer and transited smoothly to the vein. Then the two portions pack the vein around and form the outer surface of the vein. Second, at the vein/spike conjunctive site, the vein and spike are connected smoothly into a triplet. Last, at the vein/membrane/spike conjunctive site, the membrane (i.e., the outer layer of the vein) transits smoothly to the spike, packs it around, and forms its outer layer. In short, the membrane looks like a closed coat packing the wing as a whole. The smooth transition mode and the global package mode are universal assembly modes in dragonfly wings. They provide us the references for better understanding of the functions of dragonfly wings and the bionic manufactures of the wings of flights with mini sizes. Microsc. Res. Tech., 2011. © 2011 Wiley Periodicals, Inc.

CuS concaved polyhedral superstructures have been successfully prepared by a simple solvothermal reaction without using any additional surfactants and template. CuS superstructures composed of sing...

Highly (111) oriented γ-CuI crystals were successfully synthesized by a microwave-assisted method using Cu(NO3)2·3H2O and I2 as raw materials in an ethanol solution, in which ethanol plays an impor...

A new synthetic approach was developed to fabricate cross-linked polymer films covalently attached on a silicon substrate via a self-assembled monolayer (SAM) using a low energy proton beam as the initiator. The widely used silane coupling reagent 3-(mercaptopropyl) trimethoxysilane [HS(CH2)3Si(OCH3)3] was employed as an intermediate SAM to chemically bond the cross-linked polymer film to the silicon substrate. Dotriacontane was selected as a precursor that was spin-coated on the SAM-terminated silicon wafers. The film thickness can be easily controlled by spin-coating precursor solutions of different concentrations. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurements confirmed the formation of SAM on the silicon substrate and the subsequent cross-linkage between the SAM and the upper polymer film formed. The resulting cross-linked polymer films are relatively stable, with all layers covalently attached together so that the whole film could not be removed by rinsing in both organic solvent and even more reactive HF solutions. In particular, the resistance of the cross-linked polymer film towards HF etching can be useful for lithography and device fabrication for polymer based electronics. The capability of using different SAMs to attach various polymer films was also demonstrated.

Copper sulfide (CuS) concave polyhedral superstructures (CPSs) have been successfully prepared in an ethanolic solution by a simple solvothermal reaction without the use of surfactants or templates. Two typical well defined, high symmetry CuS concave polyhedrons, forming a concave truncated cuboctahedron and icosahedron were prepared. The effect of the reaction time, temperature and different Cu ion and sulfur sources on the formation of CuS CPSs were investigated and a possible formation mechanism was proposed and discussed based on gas chromatography-mass spectrometry. More importantly, we found, for the first time, that the CuS CPSs exhibit intrinsic peroxidase-like activity, as they can quickly catalyze the oxidation of typical horseradish peroxidase (HRP) substrates, 3,3',5,5'-tetramethylbenzidine (TMB) and o-phenylenediamine (OPD), in the presence of hydrogen peroxide. In addition to the recent discoveries regarding peroxidase mimetics on Fe(3)O(4) NPs and carbon nanostructures, our findings suggest a new kind of candidate for peroxidase mimics. This may open up a new application field of CuS micro-nano structures in biodetection, biocatalysis and environmental monitoring.

In this work, we demonstrate the influence of an Au buffer layer on the structure and photoluminescence (PL) properties of ZnO sol–gel thin films on Si substrates. An Au layer was deposited on the silicon substrate by the evaporation deposition method from highly pure Au (99.99%) wires. Then, a ZnO film was prepared by the sol–gel method with spin-coating technology, followed by calcinations in air at 600 °C for 1 h. The structures and morphologies of the prepared films were characterized by x-ray diffraction, energy dispersive spectrum analysis, atomic force microscopy and PL. The results show that the prepared ZnO thin film with an Au buffer layer exhibits good crystallinity and surface morphology compared with that without an Au buffer layer. Interestingly, different from other previous reports on buffer layers with PL-enhanced properties, the ZnO thin film with Au buffer layer showed an obvious violet PL-quenched property.