Catalytic behavior of V2O5 in rechargeable Li–O2 batteries

The possibility of using vanadium pentoxide (V₂O₅) as a catalyst in rechargeable lithium–oxygen (Li–O₂) batteries was studied. A V₂O₅-carbon composite was cast onto Ni foam to form a cathode. Electrochemical cells designed based on the flat cell manufactured by Hohsen Corporation were fabricated. The initial discharge capacity was 715 mA?h?g^?1, and the maximum discharge capacity reached 2,260 mA?h?g^?1 during the twelfth cycle. The cell had high capacity retention during cycling (1.24?% during cycles 2–8). V₂O₅ acted as a catalyst as well as an active material, improving the specific capacity and capacity retention of the non-aqueous Li–O₂ cell more effectively than do other materials.     

Preparation and corrosion assessment of electrodeposited Ni–SiC composite thin films

Ni–SiC composite thin films were successfully prepared via direct-current (DC) and ultrasonic pulse-current (UPC) deposition. The morphologies, mechanical properties, and corrosion properties of the films were investigated via atomic force microscopy, X-ray diffraction (XRD), Vickers hardness test, scanning electron microscope (SEM), cyclic polarization, and gravimetric analysis. The results show that the Ni–SiC composite thin films synthesized via UPC deposition possess a compact and exiguous surface morphology. The XRD results indicate that the average grain diameters of Ni and SiC in the UPC-deposited thin film are 63.6 and 38.5 nm, respectively. The maximum microhardness values for the DC- and UPC-deposited Ni–SiC composite thin films prepared are 871.7 and 924.3 HV, respectively. In the corrosion tests, the UPC-deposited films have a higher corrosion resistance than those prepared by DC deposition with the same SiC content.     

Optical properties of Nb-doped TiO2 thin films prepared by sol–gel method

In this work, we studied optical properties of pure and Nb-doped TiO₂ synthesized using a sol–gel method and deposited as thin films by spin-coating followed by annealing in air at 500 °C for 1 h. The surface elemental composition was derived from X-ray photoelectron spectra, while structure and surface morphology were investigated using X-ray diffraction and atomic force/scanning electron microscopy. Finally, the optical properties were investigated by means of UV–vis spectrophotometry and spectroscopic ellipsometry.The Nb content was determined from XPS measurements to vary between 1.8 and 4.3 at%. The XRD patterns of the deposited thin films, with a maximum thickness of about 56 nm, showed no diffraction peaks. As proven both by microscopy and spectroscopic ellipsometry studies doping TiO₂ with Nb modified the surface morphology of the samples; the grain size is increasing while the surface roughness decreases with the increase in Nb content. This is accompanied by a decrease in the refractive index and an increase of the extinction coefficient.     

Preparation of dendritic–linear polyether-modified silica sol and its application in coatings

Dendritic–linear polyether-modified silica sol (DLPS) was synthesized using diethylenetriamine, methyl acrylate, epoxy-terminated polyether, triethoxysilane, and silica sol in five steps. The prepared sol was stable and transparent. DLPS was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and particle size distribution analysis. Subsequently, DLPS was examined as a stain-resistant additive in (paint) coatings. The surface of the sample coatings with and without DLPS additive was examined by scanning electron microscopy, energy-dispersive spectrometry analysis, and contact angle analysis. The results showed that the stain-resistant additive appeared on the surface of the coating, which made the surface more compact and hydrophilic. The performance of the stain-resistant additive was examined in commercial outdoor emulsion coatings (WB200). The result showed that the presence of the stain-resistant additive could enhance the stain resistance performance of paint. Furthermore, the stain resistance performance improved with increasing amounts of additive. Specifically, the stain resistance performance of paint improved by 40.63% in the presence of 6 wt% DLPS. Therefore, the current findings demonstrate the importance of DLPS in advancing progress and application in the paint coating industry.     

Preparation of multi-coating PZT thick films by sol–gel method onto stainless steel substrates

PbZr_0.45Ti_0.55O₃ ferroelectric films have been prepared by sol–gel method, using alkoxide precursor compounds and multi-layer technique. The gel films were deposited by spin-coating onto stainless steel substrates. In order to obtain crystallization in the perovskite phase, the samples were annealed at 600–700°C for 1 min. The dependence of the electric properties on the heat-treatment temperature is studied, and the coercive electric field as a function of the material thickness is determined. By SEM photography, the microstructure of the films could be shown to be homogeneous.     

Corrosion protection by zirconia-based thin films deposited by a sol–gel spin coating method

This paper focuses on the structure and corrosion behavior of 316L stainless steel coated by inorganic ZrO₂, hybrid ZrO₂–PMMA, and combined inorganic–hybrid films. The coatings were deposited by a particulate sol–gel spin-coating route, using carboxymethyl cellulose as a nanoparticle dispersant. The electrochemical evaluations were conducted in a simulated body fluid, via potentiodynamic polarization and impedance spectroscopic experiments. According to the results, the hybrid coating presented a better corrosion protection compared to the inorganic coating, due to a lesser density of structural defects. However, the best corrosion resistance was found for a combined coating which consists of an inorganic bottom layer and a hybrid top layer, due to a desirable compromise of good adhesion and low defect density.     

Preparation of waterborne polyurethane/β-cyclodextrin composite nanosponge by ion condensation method and its application in removing of dyes from wastewater

Currently, polymer nanosponges have received extensive attention. However, developing new synthetic techniques for novel nanosponges remains a challenge. Furthermore, to date, composite nanosponge adsorbents based on waterborne polyurethane(WPU) and β-cyclodextrin(β-CD) have not been reported.Herein, a novel green method, ion condensation method, was developed in this study for the preparation of polymer nanosponge adsorbents for efficient removal of dyes from wastewater. Based on the principle ...     

Micromechanical properties of BN and B–C–N coatings obtained by r.f. plasma-assisted CVD

We have obtained highly transparent and hard BN films in a capacitively coupled r.f. plasma-assisted CVD reactor from three different gas mixtures: B₂H₆–H₂–NH₃, B₂H₆–N₂ and B₂H₆–N₂–Ar. It was found that the films were smooth, dense, and had a textured hexagonal structure with the basal planes perpendicular to the film surface. The microhardness, friction coefficient and adhesion of these coatings were measured by nanoindentation and microscratching. BC_xN_y films were also prepared in the same plasma-assisted CVD reactor from B₂H₆–N₂–CH₄ gas mixtures. The carbon content in the films was varied by using different CH₄ flow rates. These films had a less ordered structure. The mechanical properties of these films had been compared to those of hexagonal BN films. Microhardness measurements showed that there is a correlation between film composition and hardness of the BCN films.     

Preparation of nano-AlN powder by sol–gel foaming and its sintering properties

Uniformly dispersed nano-sized aluminum nitride powders were prepared by the sol–gel foaming method using aluminum nitrate as the aluminum source, sucrose as the carbon source, and ammonium chloride as the foaming agent. The effects of ammonium chloride content on the particle size and the sintering properties of aluminum nitride were investigated. The results showed that when the molar ratio of ammonium chloride to aluminum nitrate was .5, the colloidal foams were uniform, large, and fluffy, and amorphous alumina precursors with uniform particles could be prepared. Aluminum nitride powder with a particle size of 22–27 nm can be obtained by calcining these precursors in nitrogen atmosphere at 1400°C for 2 h. At the same time, aluminum nitride bulk material with a relative density of 95% can be obtained by sintering the compact samples in nitrogen atmosphere at 1700°C for 2 h.     

Preparation and antibacterial activity of Ag/SiO2 thin film on glazed ceramic tiles by sol–gel method

In the present study, silver-doped silica thin films on glazed surface of ceramic tiles were well prepared by sol–gel method to achieve antibacterial activity. Thermal treatment was done in the air at 1100 °C for two hours. The Ag/SiO₂ thin films were investigated through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and wavelength dispersive spectrometry (WDS). Atomic absorption spectroscopy (AAS) was used for the quantitative determination of the silver ion concentration being released from Ag/SiO₂ films over a 24 day period. The antibacterial effects of Ag/SiO₂ thin films against Escherichia coli and Staphylococcus aureus were also examined. From the analysis results, it was found that high temperature treated coating consists of two phases of SiO₂ and Ag based on the trapping of the Ag phase in the silica matrix. The presence of Ag elements on the surface of the coated tiles, were also observed. Thermal treatment at high temperatures caused sharp XRD peaks and high crystallinity in this system. Ag⁺ ions were released constantly and the mean release rate (±SD) was 0.104 ±0.01 μg/ml during 24 days. Coating films exhibited an excellent antibacterial performance against both bacterium.     

Preparation of polyacrylamide–montmorillonite nanocomposite and its application in Cr(III) adsorption

The polyacrylamide–montmorillonite “water in water” (PAM-MMT W/W) emulsion was prepared by dispersion polymerization method in the presence of organo-montmorillonite (OMMT). Based on the analysis of the polymerization process, the structure of material was investigated using thermogravimetry, Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy experiments. Here, the dispersion was determined to be a blend of PAM W/W emulsion and PAM network interspersed by MMT particles, this unique structure of the material was considered to provide better adsorption ability compared to PAM without MMT. Therefore, a PAM-MMT adsorbent was made from the PAM-MMT W/W emulsion, and its adsorption capacity toward Cr(III), one of the heavy metal pollutants from the tannery waste was investigated. The PAM-MMT nanocomposite was demonstrated to have good Cr(III) removal performance, the maximum adsorption capacity of the nanocomposite was found to be 59.74 mg/g at a pH of 5.5 and temperature of 70°C. Results show that pseudo-second-order kinetic model and Langmuir isotherm were applicable for Cr(III) adsorption.     

Etching process of hydrogenated amorphous carbon (a-C:H) thin films in a dual ECR–r.f. nitrogen plasma

Hydrogenated amorphous carbon (a-C:H) films deposited from CH₄ in a dual electron cyclotron resonance (ECR)–r.f. plasma were treated in N₂ plasma at different r.f. substrate bias voltages after deposition. The etching process of a-C:H films in N₂ plasma was observed by in situ kinetic ellipsometry, mass spectroscopy (MS), and optical emission spectroscopy (OES). Ex situ atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the etched film surface. XPS analysis proves that the nitrogen treatment on the a-C:H film, induced by r.f. substrate bias, causes a direct nitrogen incorporation in the film surface up to 15–17 at.% to a depth of about 20–40 Å depending on the r.f. bias. Various bonding states between carbon and nitrogen, such as tetrahedral sp³ C–N, and trigonal sp² C–N were confirmed by the deconvolution analysis of C 1s and N 1s core level spectra. The evolution of etching rate and the surface roughness in the film measured by AFM exhibit a clear dependence on the applied r.f. bias. MS and OES show the various neutral species in the N₂ plasma such as HCN, CN, and C₂N₂, which may be considered as the chemical etching products during the N₂ plasma treatment of a-C:H film.     

Structural and chemical analysis of amorphous B–N–C thin films deposited by RF sputtering

Ternary Boron–Nitrogen–Carbon (B–N–C) thin films were deposited, onto silicon substrates, by reactive radio frequency (RF) sputtering from a boron carbide (B₄C) target in a gas mixture of nitrogen and argon. The influence of the RF power (P_RF) on the structure and the chemical composition of these films are studied by Fourier transform Infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements. The two techniques reveal the presence of B, C and N atoms in the deposited films. The presence of nitrogen in the atmosphere of the deposition chamber produces ternary B–N–C films composed mainly with a mixture of B–N and CN bonds as revealed by these techniques. The boron content increases while carbon and nitrogen contents decrease with P_RF. The higher proportion of boron atoms produced a strong contribution of the boron nitride in the final compound B–N–C films.     

Electrocaloric and pyroelectric properties of PZT and PMN–PNN–PZT thin films

The electrocaloric effects (EC) of PZT and PMN–PNN–PZT films were evaluated. PZT and PMN–PNN–PZT thin films with a thickness of 500 nm were fabricated by state-of-the-art chemical solution deposition from a precursor solution with PZT and (PMN?PNN)/PZT=30/70. The polarization hysteresis loop was found to be slim and nonlinear, with smaller hysteretic behavior compared with PZT. The pyroelectric properties evaluated from polarization change and current measurement show that the properties of PMN–PNN–PZT films are superior to those of non-doped PZT films. The electrocaloric temperature changes ΔT due to applied ΔE were calculated. PZT and PMN–PNN–PZT films exhibited ΔT of 2.1 K and 3.6 K at 237.5 °C under a field of 500 kV/cm, respectively. Thermal-electrical energy converters based on pyroelectric effects were investigated for energy harvesting and possible use in ultralow-power sensor modules. The possibilities of pyroelectric energy harvesting using these PZT films were also investigated.     

A new method of bimodal support preparation and its application in Fischer–Tropsch synthesis

A simple preparation method of bimodal silica was developed by introducing SiO₂ sol into large pores of SiO₂ gel pellet directly. Cobalt supported on this kind of bimodal silica support, exhibited remarkably high activity in liquid-phase Fischer–Tropsch synthesis, which was attributed to its bimodal structure having not only a higher surface area but also a larger pore size. The support with a large surface area allowed highly dispersed cobalt particle and its large pore size improved the diffusion of reactants and products.     

Preparation and characterization of photopolymerizable organic–inorganic hybrid materials by the sol-gel method

A series of UV-curable organic–inorganic hybrid materials were prepared by the sol-gel technique and coated onto Plexiglass^® substrate. The effects of the content of EGDMA and the content of the inorganic part on various properties of the coatings, such as tensile strength, hardness, gloss, and cross-cut adhesion, were investigated. It was found that the properties of the coating were improved by the addition of an inorganic part. The thermal properties of the hybrids were enhanced by incorporating silane sol into the organic part. Furthermore, it was found that the coating containing silica had a higher char content at 800 °C than the coating without silica. SEM studies indicated that nanosized (about 50 nm) silica particles were evenly dispersed throughout the organic matrix. A photo-DSC investigation showed that the organic coating polymerized more quickly than the hybrid coating.     

Preparation of Ag-Al₂O₃ nano structures by combustion method and investigation of photocatalytic activity

In this research, Ag-Al₂O₃ nanostructures have been prepared via combustion synthesis and ammonium acetate and urea have been applied as fuels. The prepared Ag-Al₂O₃ nanostructures were characterized by DTA, XRD, SEM, TEM, and BET spectroscopy. The effect of different ratios of silver to alumina and fuel percentage on morphology and particle size of prepared products were investigated. The results showed that using ammonium acetate fuel led to the production of Ag-γ-Al₂O₃ nanocompounds, while using urea produced Ag-α-Al₂O₃. Also, the photocatalytic activity of Ag-Al₂O₃ nanostructures for Congo red degradation was evaluated by UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of Ag-Al₂O₃ was examined under UV-Vis irradiation and showed significant photocatalytic efficiency.     

Synthesis and properties of multiferroic 0.7BiFeO3−0.3BaTiO3 thin films by Mn doping

Multiferroic BiFeO₃?BaTiO₃ thin films that simultaneously exhibit ferroelectricity and ferromagnetism at room temperature were prepared by chemical solution deposition. Perovskite single-phase 0.7BiFeO₃?0.3BaTiO₃ thin films were successfully fabricated in the temperature range 600–700 °C on Pt/TiO_x/SiO₂/Si substrates. As the crystallization temperature was increased, grain growth proceeded, resulting in higher crystallinity at 700 °C. Although the 0.7BiFeO₃?0.3BaTiO₃ thin films exhibited poor polarization (P)?electric field (E) hysteresis loops owing to their low insulating resistance. The leakage current at high applied fields was effectively reduced by Mn doping at the Fe site of the 0.7BiFeO₃?0.3BaTiO₃ thin films, leading to improved ferroelectric properties. The 5 mol% Mn-doped 0.7BiFeO₃?0.3BaTiO₃ thin films simultaneously exhibited ferroelectric polarization and ferromagnetic magnetization hysteresis loops at room temperature.     

Preparation of Al2O3–ZrO2 nanocomposite films by laser chemical vapour deposition

Alumina (Al₂O₃)–zirconia (ZrO₂) nanocomposite films were prepared by laser chemical vapour deposition. α-Al₂O₃–ZrO₂ and γ-Al₂O₃–t-ZrO₂ nanocomposite films were prepared at 1207 and 1000 K, respectively. In the nanocomposite films, 10-nm-wide t-ZrO₂ nanodendrites grew inside the α- or γ-Al₂O₃ columnar grains. The γ-Al₂O₃–t-ZrO₂ nanocomposite films exhibited high nanoindentation hardness (28.0 GPa) and heat insulation efficiency (4788 J s^−1/2 m⁻² K⁻¹).     

Preparation and characterisation of LaNixCo1−xO3 thin films on polycrystalline Al2O3-substrates

The perovskite LaNi_xCo_1−xO₃ exhibits metallic conductivity with a change from p- to n-type conduction around x=0·5, thus being a candidate for electrodes or buffer layers in thin film technology. Thin films of LaNi_xCo_1−xO₃ have been grown onto polycrystalline Al₂O₃ substrates by Chemical Solution Deposition (CSD) of nitrate solutions in ethanol/butylacetate. The solutions were applied by dip-coating. After pyrolysis the compounds are formed in air at temperatures between 600°C and 750°C. Formation of the perovskite phase was confirmed by grazing angle X-ray diffraction. Electron micrographs revealed that the obtained films were smooth and crack-free and consisted of nanocrystalline LaNi_xCo_1−xO₃ particles. The thickness of the films was between 200 nm and 400 nm, depending on the conditions of the dipcoating procedure. Specific conductivities of the film were measured using the van der Pauw-method and were found to be around 400 S/cm for LaNiO₃ and around 1 S/cm for LaCoO₃ at room temperature.