Highly conductive and optical transparent Al-doped ZnO (AZO) thin film composed of ZnO with a Zn–Al–O interface was fabricated by thermal atomic layer deposition (ALD) method. The as-prepared AZO thin film exhibits excellent electrical and optical properties with high stability and compatibility with temperature-sensitive flexible photoelectronic devices; film resistivity is as low as 5.7 × 10–4 Ω·cm, the carrier concentration is high up to 2.2 × 1021 cm–3. optical transparency is greater than 80% in a visible range, and the growth temperature is below 150 °C on the PEN substrate. Compared with the conventional AZO film containing by a ZnO–Al2O3 interface, we propose that the underlying mechanism of the enhanced electrical conductivity for the current AZO thin film is attributed to the oxygen vacancies deficiency derived from the free competitive growth mode of Zn–O and Al–O bonds in the Zn–Al–O interface. The flexible transparent transistor based on this AZO electrode exhibits a favorable threshold voltage and Ion/Ioff ratio, showing promising for use in high-resolution, fully transparent, and flexible display applications.Keywords: atomic layer deposition; AZO; flexible; oxygen vacancy; TFT;

Lithium sulfide (Li2S) has drawn special attention as a promising cathode material for emerging energy storage systems due to its high theoretical specific capacity and great compatibility with lithium metal-free anodes. However, Li2S cathodes urgently require a solution to increase their poor electrical conductivity and to suppress the dissolution of long-chain polysulfide (Li2Sn, 4 ≤ n ≤ 8) species into electrolyte. To this end, we report a free-standing Al2O3–Li2S–graphene oxide sponge (GS) composite cathode, in which ultrathin Al2O3 films are preferentially coated on Li2S by an atomic layer deposition (ALD) technique. As a result, a combination of high electron conductivity (from GS) and strong binding with Li2Sn (from ultrathin Al2O3 films) was designed for cathodes. The newly developed Al2O3–Li2S–GS cathodes are able to deliver a highly reversible capacity of 736 mA h gLi2S−1 (427 mA h gcathode−1) at 0.2C, which is much higher than that of corresponding cathodes without Al2O3 (59%). Also, the long-term cycling stability of Al2O3–Li2S–GS cathodes was demonstrated up to 300 cycles at 0.5C with an excellent capacity retention of 88%. In addition, combined with density functional theory calculations, the promotional mechanism of ultrathin Al2O3 films was elucidated using extensive characterization. The ultra-thin Al2O3 film with optimal thickness not only acts as a physical barrier to Li2S nanoparticles, but provides a strong binding interaction to suppress Li2Sn species dissolution.

Although zinc oxide (ZnO), a low-cost and naturally abundant material, has a high theoretical specific capacity of 987 mA h g−1 for hosting lithium ions, its application as an anode material has been hindered by its rapid capacity fading, mainly due to a large volume change (around 228%) upon repeated charge–discharge cycles. Herein, using carbon black (CB) powder as a support, ZnO–carbon black (denoted as ZnO–CB) nanocomposites were successfully fabricated using the atomic layer deposition (ALD) method. This method was able to produce strong interfacial molecular bindings between ZnO nanoclusters and the carbon surface that provide stable and robust electrical contact during lithiation and delithiation processes, as well as ZnO nanoclusters rich in oxygen vacancies (OVs) for faster Li-ion transport. Overall, the nanocomposites were able to deliver a high discharge specific capacity of 2096 mA h g−1ZnO at 100 mA g−1 and stable cyclic stability with a specific capacity of 1026 mA h g−1ZnO maintained after 500 cycles. The composites also have excellent rate capability, and a reversible capacity at a high 1080 mA h g−1ZnO at 2000 mA g−1. The facile but unique synthesis method demonstrated in this work for producing nanostructures rich in OVs and nanocomposites with strong coupling via interfacial molecular bindings could be extended to the synthesis of other oxide based anode materials and therefore could have general significance for developing high energy density lithium ion batteries.

Metal modified C60 is considered to be a potential hydrogen storage medium due to its high theoretical capacity. Research interest is growing in various hybrid inorganic compounds-C60. While the design and synthesis of a novel hybrid inorganic compound-C60 is difficult to attain, it has been theorized that the atomic hydrogen could transfer from the inorganic compound to the adjacent C60 surfaces via spillover and surface diffusion. Here, as a proof of concept experiment, we graft Co9S8 onto C60via a facile high energy ball milling process. The Raman, XPS, XRD, TEM, HTEM and EELS measurements have been conducted to evaluate the composition and structure of the pizza-like hybrid material. In addition, the electrochemical measurements and calculated results demonstrate that the chemical “bridges” (C–S bonds) between these two materials enhance the binding strength and, hence, facilitate the hydriding reaction of C60 during the hydrogen storage process. As a result, an increased hydrogen storage capacity of 4.03 wt% is achieved, along with a favorable cycling stability of ∼80% after 50 cycles. Excluding the direct hydrogen storage contribution from Co9S8 in the hybrid paper, the hydrogen storage ability of C60 was enhanced by 5.9× through the hydriding reaction caused by the Co9S8 modifier. Based on these experimental measurements and theoretical calculations, the unique chemical structure reported here could potentially inspire other C60-based advanced hybrids.

To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanostructured sulfur cathodes are not so promising, because of the low volumetric energy density and high cost. In this work, we obtained the low-cost, scalable, eco-friendly mass production of edge-functionalized acetylene black-sulfur (FAB-S) composites by high-energy ball-milling technique for lithium sulfur batteries. The as-prepared FAB-S composite can deliver a high initial discharge capacity of 1304 mAh/g and still remain a reversible capacity of 814 mAh/g after 200 cycles at a charge-discharge rate of 0.2 C in the voltage range of 1.7–2.7 V. The observed excellent electrochemical properties demonstrate that the cathodes obtained by the facile high-energy ball-milling method as the cathode for rechargeable Li−S batteries are of great potential because it used the sole conductive additive acetylene black (AB). Such improved properties could be attributed to the partially exfoliation of AB, which not only keeps the AB's inherent advantage, but also increases the specific surface area and forms chemical bonds between carbon and sulfur, resulting in the accumulation of the polysulfides intermediate through both the physical and chemical routes.The FAB-S composite can immobilize polysulfides through both physical and chemical routes, thus could maintain a capacity of 814 mAh/g after 200 cycles at 0.2 C.Download high-res image (88KB)Download full-size image

Atomic oxygen (AO) in low Earth orbit (LEO) causes severe damages to the polymer materials used for the construction of spacecraft. To improve the AO resistance of cyanate ester (CE) which is ubiquitous in the space-structures, novel composites prepared by incorporating POSS, graphene and TiO2 (POSS-Graphene-TiO2, PGT) into CE matrix through a solution mixing method. The mass loss ratio of the resulting PGT/CE composites was significantly decreased in comparison to the pristine CE, which is due to the less surface damages. Chemical composition analysis shows that a surface passivation layer is formed on the PGT/CE composites upon exposure to the AO. Carbon fiber-reinforced PGT/CE composites (i.e., T700/PGT/CE) were fabricated. Compared with the T700/CE composite, the interlayer shear strength of the T700/PGT/CE composite was increased by 43% after the AO exposure. Our findings indicate that the PGT fillers contribute the improved AO resistance of the prepared carbon fiber/PGT/CE composites.

Flexible lithium ion batteries with high energy density have recently received tremendous interest due to their potential applications in flexible electronic devices. Herein, we report a simple high energy ball-milling technique together with vacuum filtration to fabricate a highly flexible, conductive, robust and free-standing RGO/Co9S8 nanocomposite paper with high conductivity (121 S cm−1), tensile strength (50.4 MPa) and Young's modulus (3.5 GPa) which can be directly used as a free-standing anode for flexible LIBs without binders, conducting agents and metallic current collectors. The free-standing RGO/Co9S8 anode with a high mass active material loading of 66.7 wt% Co9S8 can deliver a high specific capacity of 1415 mA h gCo9S8−1 (944 mA h gelectrode−1) and maintain 573 mA h gCo9S8−1 (382.2 mA h gelectrode−1) after 500 cycles at a current density of 1C (1C = 545 mA g−1). More importantly, the rate capability was improved by introducing RGO. The RGO/Co9S8 anode exhibited impressive capacities of 1096.70 mA h gCo9S8−1 with a capacity recuperability of 69.4% as the current returned to 0.1C. These results demonstrate that the well designed nanocomposite is of great potential as an anode for flexible LIBs. As far as we know, such improved electrochemical performance can be attributed to the nanosized Co9S8 particles with a diameter of ∼25 nm homogeneously dispersed on the surface of high conductive graphene sheets that can be obtained owing to the milling impact stress, which enhances surface electrochemical reactivity and shortens the transport length of lithium ions and electrons. What's more, the large specific surface area of the graphene sheet enables the uniform distribution of Co9S8 and offers better ability to accommodate volume expansion/shrinkage of Co9S8 during repeated charge/discharge cycles.

This work reports on the systematic comparison of the crystalline structural, morphological and hydrophobic properties of ZnO and Al-doped ZnO (AZO) thin films fabricated by atomic layer deposition and the hydrothermal method. It was revealed that the surface wettability can be largely modified by Al doping in the zinc oxide film growth process. With Al doping, the morphology of the AZO films became more complex and rough. The water contact angle of a flower-like hierarchical ZnO film (123 ± 4°) was improved by about 40° via Al doping to 160 ± 4°. We attributed the variation in surface hydrophobicity with Al doping to changes in the bond angle and distance between ZnO–H2O molecule. The computational simulations have been employed to verify the interfacial distinction between two main crystal orientations of AZO. This result suggests that Al doping can be considered a critical factor in changing the surface morphology of AZO as well as the hydrophobic properties. It is believed that the present route holds promise in the design and application of practical superhydrophobic materials.

•Low αs/ε ratio thermal control coatings on Mg alloy were prepared by the PEO way.•The presence of Zr4 + ions greatly influenced the αs and ε of the PEO coating.•The coatings were mainly composed of MgO, t-ZrO2 and an Mg–O–Zr compound.The thermal control coatings with low absorbance–emissivity ratio were successfully fabricated on AZ31 Mg alloy by plasma electrolytic oxidation (PEO) technique. The influence of Zr(NO3)4 on the thermal control properties of the PEO coatings was studied in detail. The micro-structure, element distribution, phase and chemical composition of the prepared coatings were characterized by analytical techniques. The solar absorbance and emissivity of the coatings were respectively measured by a solar absorption/reflectometer and an ultraviolet–visible-near infrared spectrophotometer. The results revealed that the coatings were composed of MgO, t-ZrO2 and an Mg–O–Zr compound (Mg0.13Zr0.87O1.87), as well as some non-crystalline phosphorus. The EDS results showed the existence of Mg, O, Zr, P, Na and K elements on the porous coating with different shapes and sizes. The thickness, roughness and thermal control properties of the coatings were greatly affected by the content of Zr4 + ions in the electrolyte. When the concentration was 10 g/L, the coating possessed the lowest absorbance–emissivity ratio (about 0.46) and the maximum thickness. Herein, the solar absorbance was 0.405 and the emissivity reached 0.873. The thermal control coating obtained by this method will broaden the spatial application of Mg alloy.

•Pure compounds Co9S8 and CoS2 have been prepared by a ball-milling process.•Pure Co9S8 has been prepared under 600 rpm with a molar ratio of 1:1 (Co:S).•Pure CoS2 has been prepared under 1000 rpm with a molar ratio of 1:2 (Co:S).•Both Co9S8 and CoS2 show enhanced electrochemical hydrogen storage capacities.Two different Co–S compounds with enhanced hydrogen storage properties, Co9S8 and CoS2, were prepared by ball-milling mixtures of Co metal and S powder. X-ray diffractometry, scanning electron microscopy and transmission electron microscopy were used to show that specific molar ratios of Co:S and ball-milling speeds and times result in pure Co9S8 and CoS2, thus overcoming a long-standing inability to obtain pure Co–S compounds via ball-milling. A galvanostatic charge–discharge process and cyclic voltammetry measurements showed that the as-obtained Co9S8 and CoS2 nanoparticles have enhanced electrochemical hydrogen storage capacities of 1.79 and 1.57 wt% hydrogen, respectively, which are higher than those previously reported. In addition, based on the corresponding X-ray photoelectron spectroscopy and cyclic voltammetry measurements, a new electrochemical hydrogen storage mechanism for the two Co–S compounds was proposed and discussed.

Binder-free S-FCNF composite films with sulfur coated uniformly on the surface of FCNFs were used as cathodes for lithium–sulfur batteries. Such cathodes have both high sulfur content (78 wt%) and large areal mass loading (8 mg cm−2), and they can deliver a high areal specific capacity of 1.87 mA h cm−2 (234 mA h gelectrode−1) after 100 cycles at 0.1 C.

TiO2 nano-particles were incorporated into cyanate ester (CE) resin to form TiO2/CE nano-composites. The effects of electron radiation on CE resin and on TiO2/CE nano-composites were investigated in a ground-based simulator that simulates space radiation conditions. Compared with CE resin, the addition of TiO2 nano-particles to the CE resin increased the bend strength and it improved the toughness before and after the electron radiation. The electron radiation damage mainly occurred in the CE resin matrix. The electric discharging resulted in the ablation of the CE resin surface when the charges were cumulated to a certain extent. The results of the mass loss and infrared (IR) experiments indicated that the electron irradiation in high vacuum broke the surface chemical bonds and that a cross-linking process occurred in the surface layer. The results of the electron paramagnetic resonance (EPR) showed that nano-TiO2 particles contribute a better resistance performance under 160-keV electron radiation.

The synergistic effects of electron and proton co-irradiation with an energy of 160 keV in ultrahigh vacuum environment on T700/cyanate composites was studied through examining the alteration of their interlayer shear strength (ILSS) and mass loss. The surface molecular structure and chemical composition of T700/cyanate composites before and after co-irradiation were studied by IR and XPS, respectively. The results indicate that under low co-irradiation fluence of less than 1.0 × 1016 e(p)/cm2, the cross-linking density of cyanate in the surface layer increased with fluence, resulting in increased ILSS of the composite. However a further increase in fluence caused the ILSS to decrease. Besides surface cross-linking, co-irradiation in high vacuum broke the surface chemical bonds. As a result, the mass loss and formation of a carbon-rich layer at thesurface of T700/cyanate composites took place.

•POSS–TiO2 organic–inorganic hybrid was synthesized and characterized.•The hybrid was incorporated into epoxy (EP) resin to form POSS–TiO2/EP nanocomposite.•The resistance to ultraviolet radiation of POSS–TiO2/EP was investigated.•The POSS–TiO2/EP exhibited excellent properties of anti-space ultraviolet radiation.Ultraviolet (UV) radiation is a severe space environmental factor, which is harmful to the durability of the polymeric materials of the spacecraft. For this reason, a novel POSS–TiO2/EP nanocomposite was synthesized by incorporating the POSS–TiO2 organic–inorganic hybrid into the epoxy (EP) resin. The effects of UV radiation on EP resin and on POSS–TiO2/EP nanocomposites were investigated in a ground-based simulator that simulates space radiation conditions. Compared with EP resin, the value of bend strength for 5.0 wt% POSS–TiO2/EP varied in a small range before and after UV radiation. Meanwhile, a typical tough feature was observed from the SEM photo for POSS–TiO2/EP nanocomposite after UV exposure. This result indicated that the POSS–TiO2/EP exhibited the excellent properties of anti-space ultraviolet radiation. The thermo gravimetric (TG) results showed that the addition of POSS–TiO2 improved the thermal-stability of EP resin matrix. The synthesized nanocomposites in this work could be used in the satellites to enhance their adaptability to the space environment and extend their service life.

Flexible lithium ion batteries with high energy density have recently received tremendous interest due to their potential applications in flexible electronic devices. Herein, we report a simple high energy ball-milling technique together with vacuum filtration to fabricate a highly flexible, conductive, robust and free-standing RGO/Co9S8 nanocomposite paper with high conductivity (121 S cm−1), tensile strength (50.4 MPa) and Young's modulus (3.5 GPa) which can be directly used as a free-standing anode for flexible LIBs without binders, conducting agents and metallic current collectors. The free-standing RGO/Co9S8 anode with a high mass active material loading of 66.7 wt% Co9S8 can deliver a high specific capacity of 1415 mA h gCo9S8−1 (944 mA h gelectrode−1) and maintain 573 mA h gCo9S8−1 (382.2 mA h gelectrode−1) after 500 cycles at a current density of 1C (1C = 545 mA g−1). More importantly, the rate capability was improved by introducing RGO. The RGO/Co9S8 anode exhibited impressive capacities of 1096.70 mA h gCo9S8−1 with a capacity recuperability of 69.4% as the current returned to 0.1C. These results demonstrate that the well designed nanocomposite is of great potential as an anode for flexible LIBs. As far as we know, such improved electrochemical performance can be attributed to the nanosized Co9S8 particles with a diameter of ∼25 nm homogeneously dispersed on the surface of high conductive graphene sheets that can be obtained owing to the milling impact stress, which enhances surface electrochemical reactivity and shortens the transport length of lithium ions and electrons. What's more, the large specific surface area of the graphene sheet enables the uniform distribution of Co9S8 and offers better ability to accommodate volume expansion/shrinkage of Co9S8 during repeated charge/discharge cycles.

Lithium sulfide (Li2S) has drawn special attention as a promising cathode material for emerging energy storage systems due to its high theoretical specific capacity and great compatibility with lithium metal-free anodes. However, Li2S cathodes urgently require a solution to increase their poor electrical conductivity and to suppress the dissolution of long-chain polysulfide (Li2Sn, 4 ≤ n ≤ 8) species into electrolyte. To this end, we report a free-standing Al2O3–Li2S–graphene oxide sponge (GS) composite cathode, in which ultrathin Al2O3 films are preferentially coated on Li2S by an atomic layer deposition (ALD) technique. As a result, a combination of high electron conductivity (from GS) and strong binding with Li2Sn (from ultrathin Al2O3 films) was designed for cathodes. The newly developed Al2O3–Li2S–GS cathodes are able to deliver a highly reversible capacity of 736 mA h gLi2S−1 (427 mA h gcathode−1) at 0.2C, which is much higher than that of corresponding cathodes without Al2O3 (59%). Also, the long-term cycling stability of Al2O3–Li2S–GS cathodes was demonstrated up to 300 cycles at 0.5C with an excellent capacity retention of 88%. In addition, combined with density functional theory calculations, the promotional mechanism of ultrathin Al2O3 films was elucidated using extensive characterization. The ultra-thin Al2O3 film with optimal thickness not only acts as a physical barrier to Li2S nanoparticles, but provides a strong binding interaction to suppress Li2Sn species dissolution.