Porous mesoporous oxides

The number of publications concerning utilization of the EISA process for fabrication of different structured materials is counted in the hundreds, which is far beyond the possibilities of this chapter to review in depth. Rather, we intend to provide a brief introduction into EISA and its application to the fabrication of functional thin films for electronic applications (e.g., electro-chromic layers and solar cells), with a special focus on fabrication of crystalline mesoporous films of metal oxides. Attention will also be given to techniques used to evaluate the pore structure of the thin films. For the other aspects of the EISA process, for example its mechanism,4 strategies for preparation of crystalline porous metal oxides,5 mesoporous nanohybrid materials,6 periodic organic silica materials,7,8 or postgrafting functionalization of mesoporous framework,9 we kindly recommend the reader to refer to the referenced comprehensive reviews. 

Abstract This review highlights how molecular Zintl compounds can be used to create new materials with a variety of novel opto-electronic and gas absorption properties. The generality of the synthetic approach described in this chapter on coupling various group-IV Zintl clusters provides an important tool for the design of new kinds of periodically ordered mesoporous semiconductors with tunable chemical and physical properties. We illustrate the potential of Zintl compounds to produce highly porous non-oxidic semiconductors, and we also cover the recent advances in the development of mesoporous elemental-based, metal-chalcogenide, and binary intermetallic alloy materials. The principles behind this approach and some perspectives for application of the derived materials are discussed. 

Once the multi-step reaction sequence is properly chosen, the bifunctional catalytic system has to be defined and prepared. The most widely diffused heterogeneous bifunctional catalysts are obtained by associating redox sites with acid-base sites. However, in some cases, a unique site may catalyse both redox and acid successive reaction steps. It is worth noting that the number of examples of bifunctional catalysis carried out on microporous or mesoporous molecular sieves is not so large in the open and patent literature. Indeed, whenever it is possible and mainly in industrial patents, amorphous porous inorganic oxides (e.g. j -AEOi, SiC>2 gels or mixed oxides) are preferred to zeolite or zeotype materials because of their better commercial availability, their lower cost (especially with respect to ordered mesoporous materials) and their better accessibility to bulky reactant fine chemicals (especially when zeolitic materials are used). Nevertheless, in some cases, as it will be shown, the use of ordered and well-structured molecular sieves leads to unique performances. 

Chen H. R., Shi J. L., Yu J., Wang L. Z. and Yang D. S., Synthesis of titanium-doped ordered porous zirconium oxide with high-surface-area, Microporous and Mesoporous Materials 39 (2000) pp. 171-176. 

We list in Table 2 a few of the systems that have been reported in the recent literature to show metal complexes supported on amorphous, non-porous oxides. We also include a few recent reports on the decorating of mesoporous supports with metal complexes. Complexes have also been introduced into porous, crystalline oxides as well as placed on organic supports." We reported the use of metal complexes as templates for forming familiar crystalline solids and new crystalline materials, some of them adopting the chirality of the metal complex. " Preparations have appeared recently using dinuclear Pd(II) complexes [Pd2Me2Cl2(dppm)2] as the precursor and these were reacted with a silica surface to produce the grafted dinuclear Pd complex with the elimination of methane from the complex. ... 

Figure P-8 TEM images of mesoporous silica nanorods synthesized by the 2D confinement of spherical micelles using different sizes of the porous aluminum oxide template (a) 25 nm, (b) 60 nm, and (c) 90 nm. (From A. Thomas et al. J. Mater. Chem. 2007, 17, 4558. Reproduced by permission of the Royal Society of Chemistry.)...

These results, coupled with the recent findings in solgel, aerogel, and modified aerogel syntheses of porous metal oxides, as well as the literature of zeolites, pillared clays, and mesoporous silicas, suggest that future investigations will lead to precise control of pore sizes, pore size distribution, and chemical functionality of the pore walls. 

Mesoporous Metal Oxide Solid Acids Three-dimensional porous metal oxides have been recently synthesized and applied to acid-catalyzed reactions. The use of mesoporous metal oxides is an interesting approach to develop a solid acid catalyst with enhanced activity. The mesopores in the oxide allow the reactants to access additional active acid sites in the pores, resulting in improved rates of acid catalysis. Mesoporous niobium oxides and tantalum oxides treated with phosphoric acid or sulfuric acid have been examined as solid acid catalysts [57-59]. These mesoporous oxides exhibited remarkable activity in Friedel-Crafts alkylation and 1-hexene isomerization in the liquid phase. For sulfated mesoporous tantalum oxides /m-TsL O ), the effect of pore size has been investigated using... 

Hudiono Y, Choi S, Shu S, Koros WJ, Tsapatsis M, Nair S (2009) Porous layered oxide/ Nafion nanocomposite membranes for direct methanol fuel cell applications. Micropor Mesopor Mat 118 427 34... 

A type H2 hysteresis loop has a triangular shape and a very steep desorption branch. Such behavior was observed for many porous inorganic oxides and was attributed to pore coimectivity effects [80], which were often defined as the presence of pores with narrow mouths (inkbottle pores), but the latter identification may be grossly oversimplified [50]. Indeed, triangular hysteresis loops were observed even for highly ordered MCM-41 materials with pore sizes of about 4-5 nm [39,55,57]. For such samples, desorption (capillary evaporation) of nitrogen from primary mesopores takes place at relative pressures of 0.4-0.5, i.e., in the region where... 

From a materials point of view an incredible development happened in the twentieth century with the preparation of porous metal oxides by the decomposition of metal salts and layered oxides [30, 31], the invention of aerogels [32], and sol-gel processing [33]. In addition, the preparation of zeolites by hydrothermal processing became important for the synthesis of very well-ordered, uniform pore structures in the micropore range. In 1990, the concept of biphasic micellar systems as a template for well-ordered mesoporous materials was successfully introduced... 

Mesoporous oxides from elements other than sihca have been reported as early as 1994. Cieslaetal. [169] found that metals such as Sb, Fe, Zn, Pb,W, and Mo also form mesoporous oxides. However, many of the mesophases obtained were lamellar and were not porous after template removal (calcination). Antonelli and Ying reported the transformation of titanium, niobium, and tantalum alkoxides into stable mesophases [170]. Subsequently, mesoporous oxides based on zirconium, hafnium, and manganese have been synthesized (for a recent review on these materials see [171]). Bagshaw and Pinnavaia [172] prepared mesoporous alumina with worm-like pores and a specific surface area of more than 400 m g . Mesoporous alumina with surface areas above 700 m g have been reported by Vaudry et al. [173]. 

Miao Z, Ding K, Wu T, Liu Z, Han B, An G, Miao S, Yang G (2008) Fabrication of 3D-networks of native starch and their application to produce porous inorganic oxide networks through a supercritical route. Microporous and Mesoporous Materials 111 104-109. 

Starodub NF, Fedorenko LL, Starodub VM, Dikij SP, Svechnikov SV (1996) Use of the silicon crystals photoluminescence to control immunocomplex formation. Sens Actuators B 35 44-47 Stefano LD, Oliviero G, Amato J, Borbone N, Piccialli G, Mayol L, Rendina I, Terracciano M, Rea I (2013) Aminosilane functionalizations of mesoporous oxidized silicon for oligonucleotide sjm-thesis and detection. J R Soc Interface 10 20130160 Steiner P, Kozlowski F, Lang W (1995a) Electroluminescence from porous Si after metal deposition into the pores. Thin Solid Films 255 49-51... 

Manganese-Based Mesoporous Materials and Manganese-Based Porous Mixed Oxides... 

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