Surface nanostructures based on tantalum and aluminum oxides

Generalized results from investigations into the processes of formation of tantalum and aluminum oxide nanostructures and their multilayered systems produced by the method of molecular lamination on a (100) silicon surface and aluminum are reported. Conditions for the layer-by-layer growth of oxide structures and multilayered low-dimensional systems with alternating zones of the said oxides are determined. Dielectric characteristics of the synthesized nanostructures are evaluated.     

Adsorption of carbon dioxide on graphene oxide supported layered double oxides

Adsorption of CO₂ on layered double oxides supported on graphene oxide has been studied under dry and wet conditions. In the first exposure to the adsorptive gas, the isotherms obtained for supported and unsupported materials are shown to fit to the Freundlich model indicating the existence of heterogeneous adsorption sites. After multiple temperature-swing cycles, the adsorption capacity decreased and the data is better described by the Langmuir model. The presence of graphene oxide is shown to reduce the loss of adsorption capacity, and helps to maintain the heterogeneity of the basic sites on the adsorbents. The use of wet gas mixtures was found to have a positive effect on the CO₂ adsorption capacity of the graphene oxide hybrids. The presence of residual sodium on the materials resulted in a Freundlich isotherm with increased adsorption capacity.     

Enhanced lithium electrochromic performance of tungsten oxide films by rapid co-synthesis of iron and tantalum oxides using cold atmospheric pressure plasma polymerization

Journal of Solid State Electrochemistry - Lithium electrochromic performance of organo-tungsten oxynitride (WOz1Cz2Nz3) films enhanced by additions of organo-iron oxynitride (FeOz1Cz2Nz3) or...     

High-performance supercapacitor electrodes based on graphene hydrogels modified with 2-aminoanthraquinone moieties

2-Aminoanthraquinone (AAQ) molecules were covalently grafted onto chemically modified graphene (CMG), and the AAQ functionalized CMG sheets were self-assembled into macroporous hydrogels for supercapacitor electrodes. The electrode based on the AAQ modified self-assembled graphene hydrogel (AQSGH) showed a high specific capacitance of 258 F g(-1) at a discharge current density of 0.3 A g(-1), which is much larger than that of a pure graphene hydrogel (193 F g(-1)). Furthermore, the AQSGH electrode exhibited excellent rate capability and a long cycle life. This is mainly due to the covalently bonded AAQ moieties contributing additional redox capacitance. Furthermore, the highly conductive graphene hydrogel scaffold provided a large specific surface area for forming electric double layers and convenient routes for charge transfer and electrolyte diffusion.     

FT-IR and FT-FIR studies of vanadium,molybdenum and tungsten oxides supported on different carriers

In the far IR region at low molybdenum loadings, Mo-SiO₂ catalysts present a pseudomolybdate or a polymolybdate species, while bulk-like MoO₃ appears at loadings close to the geometrical monolayer coverage. W-SiO₂ and V-SiO₂ spectra show bands close to those observed on the corresponding bulk oxides.In the case of TiO₂, Al₂O₃, ZrO₂ supported catalysts, a band is observed near 1000 cm^–1 which is assigned to the Mo=O stretching vibration of coordinatively unsaturated Mo ⁿ⁺ ions showing a stronger interaction with the support than one observed on silica.     

Inorganic electrochromic materials based on tungsten oxide and nickel oxide nanostructures

Electrochromic devices, which dynamically change color under applied potentials, are widely studied for use in energy-efficient smart windows. The operation of electrochromic materials and devices involves the gain or loss of electrons and simultaneous insertion/extraction of ions with opposite charges to balance the internal electric fields. The performance is therefore limited by kinetics of charge transport in the electrochromic materials as well as ion migration in the electrolyte, materials and at their interfaces. Nanostructured electrochromic materials have an extremely short charge transport distance facilitating charge transport in electrochromic devices and large specific surface area for interaction with electrolytes, and thus may provide fast charge and ions transport, high electrochemical activities and remarkable enhancement of electrochromic properties. The recent progress in application of nanostructures, including nanoparticles, 1D and 2D nanostructures, in metal oxide electrochromic materials and devices is reviewed. A perspective on the development trends in electrochromic materials and devices is also proposed.     

pH electrodes based on iridium oxide films for marine monitoring

The pH is an important parameter that affects the growth and development of marine organisms, environmental changes, and industrial and agricultural production processes. Nowadays, important trends in pH detection and analysis are higher stability, adaptation to extreme environmental conditions, miniaturization, portability, and digital intelligence. Several studies have focused on the application of the iridium oxide film (IROF) pH electrodes in water quality monitoring and physiological analysis. The central aim of this work was to review the preparation techniques of the IROF pH electrodes and to expand their application in the field of marine monitoring. The studied methods include electrochemical deposition, electrochemical growth, sputtering deposition, heat treatment, and novel preparation methods. The IROF pH electrodes prepared via these methods are more sensitive, have a wider pH measurement ranges, and can be miniaturized further than traditional glass and pH photometer. Hence, in environmental analysis, combining IROF pH electrodes with wireless technology for the physiological and biochemical analysis of marine organisms, seawater, and sediment pore water is an important development tendency.     

High-performance supercapacitor material based on Ni(OH)2 nanowire-MnO2 nanoflakes core-shell nanostructures

Ni(OH)(2)/MnO(2) core-shell nanowires with a nanoflake surface have been designed and synthesized, and can be applied not only in neutral electrolytes (355 F g(-1), 70.4 wt% MnO(2)) but are also appropriate for alkaline electrolytes (487.4 F g(-1), 35.5 wt% MnO(2)), with high cycling stability due to the synergistic effect between the core and shell.     

Methane oligomerization on supported metallic oxides

Pt–Re/Al₂O₃ prepared under different impregnating conditions were characterized by TPR and tested in naphtha and n-heptane reforming. Catalysts showed different Pt and Re radial distributions and reduction profiles. When both metals interact, higher dehydrocyclization and conversion are retained after a deactivation step, meanwhile, when Re is segregated from Pt the catalytic performance is negatively affected.

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Pt–Re/Al₂O₃, , -. Pt Re . , , Re Pt .

     

Development of high-performance supercapacitor electrodes using novel ordered mesoporous tungsten oxide materials with high electrical conductivity

An ordered mesoporous WO(3-x) material was employed for use as a supercapacitor electrode. This material exhibited a high rate capability and an excellent capacitance (366 μF cm(-2), 639 F cm(-3)), which were probably attributed to the large ordered mesopores, high electrical conductivity, and high material density.     

High-performance supercapacitor based on ultralight and elastic three-dimensional carbon foam/reduced graphene/polyaniline nanocomposites

A novel supercapacitor based on ultralight and elastic three-dimensional porous melamine foam-derived macroporous carbon/reduced graphene oxide/polyaniline nanocomposites were fabricated, which showed great electrical performance and cycle performance.     

High-performance hybrid supercapacitor based on pure and doped Li4Ti5O12 and graphene

Journal of Solid State Electrochemistry - Graphene nanosheets (G) and pure, as well as doped Mg-, Mn-, V-Li4Ti5O12, spinel structure have been synthesized. As-prepared materials were characterized...     

Electrodes based on nanodispersed titanium and tungsten oxides for a sensor of dissolved oxygen

It is suggested to use films of nanodispersed Ti and W oxides as electrodes in a sensor for dissolved oxygen. It is shown that films of this kind have stable characteristics in electroreduction of O₂ in saline.     

磷钨酸盐修饰的氧化钨薄膜的制备与电致变色性质研究

为了提高WO₃纳米粒子薄膜的光学对比度,利用层接层自组装方法,将Keggin型结构的磷钨酸盐H₃[α-PW₁₂O₄₀]与WO₃纳米粒子复合,制备[PEI/PW₁₂/PEI/WO₃]₂₀复合膜.采用扫描电镜、紫外光谱和电化学工作站对复合膜的形貌及电致变色性能进行研究,结果表明:该复合膜与单纯的WO₃纳米粒子薄膜相比,光学对比度提高了117.28%,且这种复合膜提供了较大的H⁺扩散系数,可以获得更好的电致变色性能.     

Carbon/titanium oxide supported bimetallic platinum/iridium nanocomposites as bifunctional electrocatalysts for lithium-air batteries

Platinum (Pt) and iridium (Ir) catalysts are well known to strongly enhance the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics, respectively. Pt–Ir-based bimetallic compounds along with carbon-supported titanium oxides (C–TiO₂) have been synthesized for the application as electrocatalysts in lithium oxygen batteries. Transition metal oxide-based bimetallic nanocomposites (Pt–Ir/C–TiO₂) were prepared by an incipient wetness impregnation technique. The as-prepared electrocatalysts were composed of a well-dispersed homogenous alloy of nanoparticles as confirmed by X-ray diffraction patterns and Fourier transform scanning electron microscopy analyses. The electrochemical characterizations reveal that the Pt–Ir/C–TiO₂ electrocatalysts were bifunctional with high activity for both ORR and OER. When applied as an air cathode catalyst in lithium-air batteries, the electrocatalyst improved the battery performance in terms of capacity, reversibility, and cycle life compared to that of cathodes without any catalysts.     

Application of ammonia intermittent temperature-programmed desorption to evaluate surface acidity of tungsten oxide supported on activated carbon

Intermittent temperature-programmed desorption of ammonia was used to study the strength and population of surface acid sites of tungsten oxide supported on activated carbon pretreated at 350 and 700 degrees C. Catalysts pretreated at 350 degrees C showed two types of surface acid sites and desorption occurred with free readsorption until a temperature of around 300 degrees C was reached. Pretreatment at 700 degrees C produced three different states of ammonia adsorbed on the catalysts and desorption occurred with free readsorption.