Surfactant-assisted Method

Mesoporous ceria and ceria-zirconia powders with high surface area have also been prepared using a surfactant-assisted method to prepare catalysts containing Ce02 

Sample Cacination temp. / K Average size / nm Surface area / m g  

The enhancement of the surface area of ceria-based materials related to the surfactant effect that reduces the surface tension inside the pores by decreasing capillary stress during drying and calcination processes. Better thermal stability is related to the structural arrangement and the morphology of the inorganic-organic 

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Ceria-zirconia nanophases were synthesied by a surfactant-assisted method. The refined structural data concerning the crystallite size, lattice parameters, structural microstrain, cationic occupy number and cationic defect concentration are reported. Zirconium addition into the cubic structure of ceria inhibits crystal sintering but leads to structure distortion. Different CO-metal bonds are formed when CO chemisorbs on Pd-loaded CesZr. x02 catalysts. Catalytic tests reveal that the lower zirconium content benefits the CO oxidation. 

Nanosized ceria-zirconia materials with improved thermal stability can be prepared by using the surfactant-assisted method. Structural refinements confirm that the nanocrystals contain structural microstrain and cationic lattice defects. Zirconium addition to ceria supresses the crystal sintering and imporves the thermal stability but leads to structure distortion. Both catalytic tests and CO-chemisorption show that Pd supported ceria-zirconia nanoparticles are active for CO oxidation. 

High-surface-area mesoporous CuO- Fc203 catalysts with various CuO content (denoted as FeCuX, X=10, 15, 20, 33, 50 mol.%,) were prepared by a surfactant-assisted method of nanocrystalline particle assembly. The method is described in details in Ref [4]. All samples were characterized by XRD, N2 adsorption, TEM, H2-TPR and Mdssbauer spectroscopy. Mossbauer spectra (MS) were obtained with a Wissel electromechanical Mdssbauer spectrometer (Wissenschaftliche Elektronik GmbH, Germany) working at a... 

Ngamsinlapasathian, S. Pavasupree, S. Suzuki, Y. Yoshikawa, S. 2006. Dye-sensitized solar cell made of mesoporous titania by surfactant-assisted templating method. Solar Energy Mater. Solar Cells 90 3187-3192. 

Nanotubes and nanowires of II—VI semiconductor compounds such as CdS and CdSe have been obtained by a soft chemical route involving surfactant-assisted synthesis.28,75 For CdSe nanotubes, the metal oxide was reacted with the selenidizing reagent in the presence of a surfactant such as Triton 1G0X. Substantial amounts of nanotubes were obtained by this method (Fig. 25a and b). Annealing of the as-prepared nano-... 

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. 

To increase dispersion or surface area of salt-enzyme preparations in organic media, a method of preparing surfactant-assisted salt enzyme nanodispersions (SSENDs) was explored. The goal was to create a fine dispersion of the salt enzyme lyophilized particles with the use of a siufactant prior to lyophilization by creation of a fine emulsion, followed by removal of solvent and water by lyophilization. Microscopic observation of the emulsion indicated a submicron dispersion of the aqueous phase in the solvent. The results of the ertzyme assay using SSENDs catalyst is shown in Table 3. This experiment was conducted in hexane to determine if such a preparation can enhance activity of the enzyme because posdyophilization addition of the surfactant did not improve the rate of the reaction. The results show that a two- to threefold higher rate can be obtained by preparation of the salt-SC using the SSENDs preparation method. 

There are many experimental techniques for the preparation of nanowires from the liquid phase. A considerable research effort has been expended in developing template-free methods for the deposition of one-dimensional nanostructures in a liquid environment the most important procedures are hydrothermal methods, electrospinning,sonochemical and surfactant assisted. 

We have discussed in the previous sections about the physical properties and surfactant-assisted self-assembly formations of metal nanoparticles. These assembling methods are quite beautiful and intelligent, because they are induced by the spontaneous driving force for assembling by smart choice of the conditions. In the cases of practical use, however, the methods described below are rather tend to be required (1) the method to make a desirable size, length, shape, architecture and position, etc., (2) a simple and easy method, and (3) highly stable assemblies. From these viewpoints, as a final section for a preparation of nanoparticle assembly, we introduce here the template assisted self-assemblies of nanoparticles. This section is classified to three stories corresponding to the dimension (such as ID, 2D and 3D) of the template and assembly. 

Zinc 5,10,15,20-tetrakis(4-pyridyl)porphyrin, ZnTPyP, was assembled to form monodimensional supramolecular nanostructures via surfactant-assisted self-assembly (SAS) method, with GO acting as a sheet-Uke surfactant [106]. This SAS-enhanced photocatalytic activity for the photodegradation of Rhodamine B under visible-light irradiation with respect to ZnTPyP nanoassemblies formulated via a conventional SAS, with hexadecyltrimethylammonium bromide used as surfactant. 

Unlike hard templates (alumina, zeolites, etc.) which require many synthetic steps, surfactant templates may be a convenient alternative. The morphology of PANI and PPy (spheres, wires, flat films) can be modulated though the use of adsorbed surfactants aided by co-adsorbing molecules aligned nanowires of PANI produced by this template assisted method can be self-assembled over large areas for the improvement of microelectronic and sensor devices, as depicted in Fig. 1.11 [139]. 

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. 

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