Surfactant-assisted sol-gel

J. Joseph, C.-Y. Tseng, C.-J. Pan, H.-M. Chen, C.-W. Lin, K.C. PiUai, B.-J. Hwang, Growing well-defined monodispersed silica in polyimide host membranes nsing a surfactant assisted sol-gel process. Polymer 51 (2010) 5663-5668. 

Unfortunately, the surface area and porosity of perovskites are insignificant compared to many of the mesoporous oxides. Because of this, an advanced interaction of reactants with the active sites of the catalysts is limited. To overcome this, various attempts were made to synthesize perovskite oxides with high surface areas using different methods such as the decomposition of metal complexes, the sol-gel, or the surfactant-assisted sol-gel and polymerized complex methods. 

Mesoporous structures are made by random packing of initially dispersed nanoparticles followed by thermal processing. In addition, they can be made into periodic structures by surfactant-assisted (sol-gel) formation of an oxide from solutions (Lu et al., 1997). Random-packed macroporous structures are commonly made by ceramic green processing... 

Sreethawong T, Ngamsinlapasathian S, Suzuki Y, Yoshikawa S (2005) Nanociystalline mesoporus Taz-based photocatalysts prepapred by surfactant-assisted templating sol-gel process photocatalytic H2 evolution. J Mol Catal A Chem 235 1-11... 

Sol-gel processes are also suitable for lanthanide oxide formation, as could be shown by the use of Tb(acac)3 and Dy(OBu- )3 in acetylacetone" . Tb203 crack- and pine-hole-free, dense and smooth microstructured buffer layers were produced on nickel tapes by a reel-to-reel continuous sol-gel process. The authors report that the film properties can be strongly influenced by solution components, temperature, time and atmosphere. Nanocrystalline mesoporous dysprosium oxide Dy203 with narrow monomodal pore size distribution can be approached by a combined sol-gel process with a surfactant-assisted templating technique . The spherical Dy203 nanoparticles were formed with aggregations. 

There exist a variety of methods to synthesize quasi-one-dimensional nanostructured materials, which include but not limited to vapor phase growth, template-assisted synthesis, sol-gel deposition, surfactant-assisted growth, sonochemical method, hydrothermal method, and electrochemical deposition [21], Among the various methods, the electrochemical anodization method is one of the simplest and cheapest methods to synthesize ordered quasi-one-dimensional nanostructure. 

Structured micro-assemblies built from nanoparticle primary subunits can be classified into several categories arranged, hierarchical, and oriented nanoparticle assemblies. In addition to this, one-, two-, and three-dimensional systems exist under each of these divisions. Methods of preparation can differ vastly depending on the material being synthesized or processed, i here is hardly a universal method that can be applied for the majority of chemistries, but there are several general approaches involving wet chemical techniques that are commonly used. Examples of commonly used techniques include solvothermal, sol-gel processing, surfactant-assisted synthesis, or solvent-controlled synthesis [73]. 

Surfactants have also been used as a soft template for the electrochemical deposition of mesoporous silica films. Walcarius et al [28] demonstrated the elec-trochemically assisted self-assembly of surfactant-templated silica thm films on various conductive substrates (Au, Pt, glassy carbon, ITO, and Cu). The films were highly ordered and homogeneous over wide areas. Figure 12.10 shows the TEM images of the electrodeposited mesoporous silica films. Hexagonal pores are seen to be well ahgned perpendicular to the surface. It is believed that the cathodic potential applied on the substrate not only drove the sol-gel film... 

Based on the control of sol-gel deposition, hierarchically porous silica-based materials with a bimodal pore system (mesopores/large meso/macropores) and a diversity of dopant elements (Al, Ti, V, and Zr) could be prepared by using a one-pot surfactant-assisted procedure [78]. Another example includes the preparation of nonionically templated [Si]-MSU-X mesoporous silicas with bimodal pore systems by adding dilute electrolytes. 

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