Hybrid cathode materials for lithium-sulfur batteries

This review demonstrates the approaches to fabricate hybrid cathode materials for lithium-sulfur batteries. This short review does not claim to cover all recently published data; instead, an effort is aimed to show how the critical issues on carbon – sulfur hybrid are addressed based on selected articles in last couple of years. The influence of porous structure of carbon, the confinement effect of polysulfides in narrow micropores, and importance of hierarchical porosity are explained. Besides, the heteroatom doping on carbon in carbon–sulfur hybrids plays a vital role on improvement of bulk electronic conductivity of electrode. This review presents the twin polymerization strategy for direct preparation of nanoscale intermixed hybrid materials. Finally, the formation of sulfur containing copolymers by reacting sulfur melt with functional vinyl monomers are shown in this review with selected examples postulating the respective potential for future generation energy storage technology from the viewpoint of industrial applications.     

Organic-inorganic hybrid materials based on N=C=O functionalised silan modified with titanium and zirconium

This work investigates the influence of the precursor trimethylsilil isocyanate on the sol-gel synthesis of hybrid materials. The obtained Si−O−C−N network is additionally modified by titanium and zirconium alcoxypropoxides in the range of 10 to 30 wt. %. The structure of the obtained hybrid materials before and after pyrolysis up to 1100°C was investigated by methods of XRD, FTIR and ²⁹Si MAS NMR. We established that the hybrid structure was stable up to 600°C based on IR study. The structural transformation of the hybrid materials into oxycarbonitrogen system started at 800°C. The network of the hybrids modified by titanium remained stable and amorphous up to the final temperature of the pyrolysis (1100°C) compared to the gels modified by more than 10 wt.% Zr. It was confirmed by XRD analysis that the last mentioned are nanocomposite materials, built from carbooxynitrogen vitreous matrix and ZrO₂-nanocrystals (tetragonal). The NMR method verified the presence of heterometallic bonds (Si−O−Ti and Si−O−Zr) and Q₄, ZrQ₃ or TiQ₃, NSiO₃ and D structural units in the gels.     

Sol-gel synthesis of titanium dioxide and titanium dioxide-hydroxypropyl cellulose hybrid material and electrorheological characteristics of their dispersions in poly(dimethylsiloxane)

Particles of titanium dioxide and titanium dioxide-hydroxypropyl cellulose organic-inorganic composite are synthesized by the sol-gel method. The effects of an electric field on the shear stress, viscosity, tensile and compression stresses of dispersions of titanium dioxide, the hybrid material, and titanium dioxide-hydroxypropyl cellulose mechanical mixture are investigated. It is established that the value of the electrorheological effect observed for hybrid material dispersions is higher than that for dispersions of titanium dioxide and mechanical mixtures of the materials.     

Mechanical properties of hybrid inorganic-organic framework materials: establishing fundamental structure-property relationships

The mechanical properties of hybrid framework materials, including both nanoporous metal-organic frameworks (MOFs) and dense inorganic-organic frameworks, are discussed in this critical review. Although there are relatively few studies of this kind in the literature, major recent advances in this area are beginning to shed light on the fundamental structure-mechanical property relationships. Indeed research into the mechanical behavior of this important new class of solid-state materials is central to the design and optimal performance of a multitude of technological applications envisaged. In this review, we examine the elasticity of hybrid frameworks by considering their Young's modulus, Poisson's ratio, bulk modulus and shear modulus. This is followed by discussions of their hardness, plasticity, yield strength and fracture behavior. Our focus is on both experimental and computational approaches. Experimental work on single crystals and amorphized monoliths involved primarily the application of nanoindentation and atomic force microscopy to determine the elastic moduli and hardness properties. The compressibility and bulk moduli of single crystals and polycrystalline powders were studied by high-pressure X-ray crystallography in the diamond anvil cell, while in one instance spectroscopic ellipsometry has also been used to estimate the elastic moduli of MOF nanoparticles and deposited films. Theoretical studies, on the other hand, encompassed the application of first principles density-functional calculations and finite-temperature molecular dynamics simulations. Finally, by virtue of the diverse mechanical properties achievable in hybrid framework materials, we propose that a new domain be established in the materials selection map to define this emerging class of materials (137 references).     

Pyrolysis behaviour of titanium dioxide-poly(vinyl pyrrolidone) composite materials

Inorganic-organic hybrid materials are studied due to the unique properties they exhibit. As these materials become more widely applied, particularly as precursor materials for forming inorganic materials, it is essential that the pyrolysis behaviour is understood. Transparent yellow hybrid materials consisting of titanium dioxide and poly(vinyl pyrrolidone) were prepared using sol-gel processing techniques. The hybrids maintained their transparency up to the highest achieved inorganic loading of 57 wt.%. These materials were characterised using thermogravimetric analysis in which the organic component was pyrolysed. The resultant chars were then investigated using optical microscopy, x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The inorganic loading had an effect on char formation, with higher loadings leading to the formation of pyrolysis intermediates which were less apparent in samples of lower inorganic content. The pyrolysis intermediates were found to be carbon-rich.     

Reactions of titanium alkoxide with SiH containing polymers as a route to titanium/siloxane hybrid materials with enhanced refractive index

Reactions of titanium tetrabutoxide with polyhydromethylsiloxane (PHMS) and with some hydromethylsiloxane copolymers were used for synthesis of light transparent materials having enhanced refractive index. The FTIR, ¹H NMR and ²⁹Si NMR spectroscopies were used to study the reaction between PHMS and titanium tetrabutoxide in toluene. Reaction of SiH functional siloxane polymers with titanium tetrabutoxide results in a titanium-containing heterosiloxane prepolymers that are stable under anhydrous anaerobic conditions. Exposure of the resulting materials to humid air transforms them into light transparent titanium/siloxane nanocomposites with enhanced refractive index. The films of these composites formed during the spin-coating process were characterized by UV–Vis, ellipsometry, IR and ²⁹Si NMR spectroscopies and transmission electron microscopy (TEM). Titanium/siloxane hybrid films obtained on the basis of poly(phenylmethylsiloxane-co-hydromethylsiloxane) copolymer are free of cracks and have a refractive index of up to 1.60.     

Old materials with new tricks: multifunctional open-framework materials

The literature on open-framework materials has shown numerous examples of porous solids with additional structural, chemical, or physical properties. These materials show promise for applications ranging from sensing, catalysis and separation to multifunctional materials. This critical review provides an up-to-date survey to this new generation of multifunctional open-framework solids. For this, a detailed revision of the different examples so far reported will be presented, classified into five different sections: magnetic, chiral, conducting, optical, and labile open-frameworks for sensing applications. (413 references.)     

非金属元素掺杂纳米二氧化钛

二氧化钛在光电转化、光催化等众多领域具有重要的应用价值,但较宽的禁带宽度和较低的电子传递效率导致其光利用率较低.离子掺杂和纳米化是改变其能带结构、提高电子传输能力的有效策略,根据掺杂离子的性质,可分为金属离子掺杂和非金属元素掺杂.与传统二氧化钛相比,纳米二氧化钛具有特殊的表面效应和粒度效应,其化学活性、耐热性等都强于传...     

Synthesis and properties of colloidal heteronanocrystals

Colloidal heteronanocrystals (HNCs) can be regarded as solution-grown inorganic-organic hybrid nanomaterials, since they consist of inorganic nanoparticles that are coated with a layer of organic ligand molecules. The hybrid nature of these nanostructures provides great flexibility in engineering their physical and chemical properties. The inorganic particles are heterostructured, i.e. they comprise two (or more) different materials joined together, what gives them remarkable and unique properties that can be controlled by the composition, size and shape of each component of the HNC. The interaction between the inorganic component and the organic ligand molecules allows the size and shape of the HNCs to be controlled and gives rise to novel properties. Moreover, the organic surfactant layer opens up the possibility of surface chemistry manipulation, making it possible to tailor a number of properties. These features have turned colloidal HNCs into promising materials for a number of applications, spurring a growing interest on the investigation of their preparation and properties. This critical review provides an overview of recent developments in this rapidly expanding field, with emphasis on semiconductor HNCs (e.g., quantum dots and quantum rods). In addition to defining the state of the art and highlighting the key issues in the field, this review addresses the fundamental physical and chemical principles needed to understand the properties and preparation of colloidal HNCs (283 references).     

Sol–gel derived organic–inorganic hybrid materials: synthesis,characterizations and applications

Organic/inorganic hybrid materials prepared by the sol–gel approach have rapidly become a fascinating new field of research in materials science. The explosion of activity in this area in the past decade has made tremendous progress in both the fundamental understanding of the sol–gel process and the development and applications of new organic/inorganic hybrid materials. Polymer-inorganic nanocomposite present an interesting approach to improve the separation properties of polymer material because they possess properties of both organic and inorganic such as good permeability, selectivity, mechanical strength, and thermal and chemical stability. Composite material derived by combining the sol–gel approach and organic polymers synthesis of hybrid material were the focus area of review It has also been demonstrated in this review that a more complete understanding of their structure–property behavior can be gained by employing many of the standard tools that are utilized for developing similar structure–property relationships of organic polymers. This review article is introductory in nature and gives introduction to composite materials/nanocomposite, their applications and the methods commonly employed for their synthesis and characterization. A brief literature survey on the polysaccharide templated and polysaccharide/protein dual templated synthesis of silica composite materials is also presented in this review article.     

Photoactive organic-inorganic hybrid materials: From silylated compounds to optical applications

This review summarizes several aspects of type II photoactive organic-inorganic hybrid materials prepared from silylated fluorophores, including their photophysical properties and uses. In this sense, several examples are presented and discussed taking the nature of the silyl derivative into account. Applications as latent fingerprints detection, chemosensors for metal cations, anions, pH, heavy metals, and small organic molecules, as well as recent use as drug delivery systems, bioimaging, organic solar cells, aerogels, and highly fluorescent hybrid materials, are reported and compared to the literature. Also, fluorescent type II organic-inorganic hybrid materials from non-silylated fluorophores, prepared with binding agents, such as 3-(triethoxysilyl)propyl isocyanate (TESPIC), 3-mercaptopropyltriethoxysilane (TMMPS), or 3-isocyanato propyltrimethoxysilane (ICPTES) are also covered in this review.     

Non-hydrolytic sol-gel routes to heterogeneous catalysts

Oxides and mixed oxides have a tremendous importance in the field of heterogeneous catalysis, serving either as catalysts or as supports for active species. The performance of a catalyst depends directly on its composition, texture, structure and surface properties, which have to be precisely controlled and adapted to each application. In this context, the sol-gel process is a unique tool for the preparation and understanding of catalytic materials, owing to its exceptional versatility. In the last 10 years, the non-hydrolytic sol-gel (NHSG) or non-aqueous sol-gel process based on nonhydrolytic condensations in nonaqueous media has established itself as a simple and powerful method for the design of a wide range of oxide, mixed oxide and hybrid materials with controlled composition, morphology, texture and structure. NHSG proved particularly interesting for the preparation of catalytic materials, notably mesoporous xerogels, single site catalysts and highly crystalline nanoparticles. This critical review addresses the application of NHSG to the preparation of heterogeneous catalysts, emphasizing the specificities of this process, and giving a comprehensive overview of the literature (251 references).     

A review of electrode materials for electrochemical supercapacitors

In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).     

PMMA-TiO2有机无机杂化玻璃的制备与表征

有机无机杂化材料是随着对溶胶凝胶方法的广泛研究而发展起来的，有时它们被称为ORMOSILS（OrganicallyModifiedSilicates）[1,2]或ORMOCERS（OrganicallyModifiedCerandcs）[2]．溶胶凝胶过程通过溶液化学（WetChemistry）的途径来形成无机骨架，在过去的几十年里，被广泛应用     

Synthesis and properties of photosensitive polyimide-nanocrystalline titania optical thin films

In this study, synthesis, morphology, and properties of high refractive index photosensitive polyimide-nanocrystalline titania hybrid materials are reported. A soluble polyimide grafted with carboxylic acid or methacrylate groups (P1) was first synthesized from 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 3,5-diaminobenzoic acid (DABA), 4-aminobenzoic acid (4ABA), and 2-hydroxyethyl methacrylate (2HEMA). The residual carboxylic acid groups could undergo an esterification reaction with titanium butoxide to provide an organic-inorganic bonding. On the other hand, the grafted methacrylate groups rendered photosensitive property for photopatterning. A homogeneous hybrid solution was obtained through the formulation on different mole ratios of titanium butoxide/carboxylic acid, water/acid content in a mixed solvent. It was followed by spin-coating, photocuring and post-baking. The titania domain size in the hybrid materials analyzed by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) was around 4-7 nm. The prepared optically transparent films had tunable refractive index (1.583 < n < 2.029), relatively good surface planarity and high thermal stability. A fine pattern with a line width of 50 μm was produced by direct lithographic process on the hybrid films. The present study demonstrates a novel approach for preparing high refractive index hybrid photosensitive materials with patternability.     

Playing with organic radicals as building blocks for functional molecular materials

The literature has shown numerous contributions on the synthesis and physicochemical properties of persistent organic radicals but there are a lesser number of reports about their use as building blocks for obtaining molecular magnetic materials exhibiting an additional and useful physical property or function. These materials show promise for applications in spintronics as well as bistable memory devices and sensing materials. This critical review provides an up-to-date survey to this new generation of multifunctional magnetic materials. For this, a detailed revision of the most common families of persistent organic radicals-nitroxide, triphenylmethyl, verdazyl, phenalenyl, and dithiadiazolyl-so far reported will be presented, classified into three different sections: materials with magnetic, conducting and optical properties. An additional section reporting switchable materials based on these radicals is presented (257 references).     

Titanium-Oxo Clusters, Versatile Nanobuilding Blocks for the Design of Advanced Hybrid Materials

This review describes the major advances made on titanium-oxo clusters chemistry and their derived hybrid materials. The main synthesis procedures, the cluster structures presented in literature, and the relation between the titanium-oxo clusters condensation degree and poisoning ratio are discussed. The tuned organo-functionalisation of the titanium-oxo based nanobuilding blocks allows to develop a LEGO-like chemistry, able to direct the assembling of a large variety of structurally well defined complex hybrid architectures.     

Titanium-Oxo Clusters, Versatile Nanobuilding Blocks for the Design of Advanced Hybrid Materials

Summary. This review describes the major advances made on titanium-oxo clusters chemistry and their derived hybrid materials. The main synthesis procedures, the cluster structures presented in literature, and the relation between the titanium-oxo clusters condensation degree and poisoning ratio are discussed. The tuned organo-functionalisation of the titanium-oxo based nanobuilding blocks allows to develop a LEGO-like chemistry, able to direct the assembling of a large variety of structurally well defined complex hybrid architectures.     

Recent advances in anode materials for sodium - and potassium-ion hybrid capacitors

With the advent of the post–lithium-ion era, sodium- and potassium-based energy storage devices are intensively focused in the recent years. The novel sodium- and potassium-ion hybrid capacitors couple with the merits of supercapacitors and secondary batteries and thus are widely explored. A typical hybrid capacitor is generally constructed by combining a battery-type anode and a capacitive-type cathode, which presents both high energy density and power features. The design and fabrication of anode materials with high rate capability and long life to match the capacitive cathode is a critical issue. In this short review, the newly developed anode materials in nonaqueous capacitors are systematically analyzed. Based on a comprehensive summarization, the challenges for further practical applications of anode materials are prospected.