Inorganic materials, templated synthesis

By using other templates, the size of metal nanoparticles can be also controlled. Chen et al. reported the sonochemical reduction of Au(III), Ag(I) and Pd(II) and synthesis of Au, Ag and Pd nanoparticles loaded within mesoporous silica [48,49]. Zhu et al. also reported the sonochemical reduction of Mn04 to Mn02 and synthesis of Mn02 nanoparticles inside the pore channels of ordered mesoporous cabon [50]. Taking into account these reports, the rigid pore of inorganic materials can be used as a template for the size controlled metal nanoparticle synthesis even in the presence of ultrasound. 

Most examples discussed so far made use of amorphous inorganic supports or sol-gel processed hybrid polymers. Highly disperse materials have recently become accessible via standard processes and, as a result, materials with various controlled particle size, pore diameter are now available. Micelle-templated synthesis of inorganic materials leads to mesoporous materials such as MCM-41, MCM-48, MSU, and these have been extensively used as solid supports for catalysis [52]. Modifications of the polarity of the material can increase the reactivity of the embedded centre, or can decrease its susceptibility to deactivation. In rare cases, enhanced stereo- or even... 

The synthesis procedure for mesoporous material is simple, and synthesis parameters can be controlled easily. The simple procedure does not mean that the reactions or interactions among reactants in the synthesis system are simple. Many complicated reactions, interactions, and assemblies occur in the mesoporous material synthesis system. The synthesis involves three main components Inorganic species for the formation of the inorganic wall template (surfactant in most cases) whose assembly will guide the formation of mesophase the reaction media (solvent). Figure 8.3 shows the interactions between the three main components.[59] These interactions play the key roles during synthesis. The surfactant molecules in the solution will self-assemble into a micelle or liquid-crystal phase of course, various factors can affect the assembly process,... 

Highly ordered mesoporous silica can be regenerated from a mesoporous carbon CMK-3 that is a negative replica of mesoporous silica SBA-15, indicating reversible replication between carbon and inorganic materials.[193] The advantage of this synthesis method is that it does not need to make the same silica material (template). This method is likely to be a valuable complement to the existing methods for the fabrication of new mesoporous silicas and other composition materials. 

Two kinds of template, viz. hard template and soft template, are usually available for nanocasting processes. The true liquid crystal templating synthesis can be considered a soft-template process. In general, the hard template means an inorganic solid. For example, mesoporous silica as a template to replicate other materials, such as carbon or metal oxides, by which the pore structure of the parent can be transferred to the generated porous materials. A 3-D pore network in the template is necessary to create a stable replica. Mesoporous silica and carbon are commonly used templates for nanocasting synthesis. 

Morphological control of materials is required to obtain unique, often advantageous, and enhanced material properties. This chapter reviews recent research on the use of organic templates for the transcriptive synthesis [1] of inorganic materials, in particular silica and metal oxides, with controlled structures. 

Figure 1. Schematic illustration of hollow polyelectrolyte capsule formation (a-c) followed by the selective inorganic synthesis inside (d-e). a-b layer-by-layer precipitation of poly(styrene sulfonate), poly(allylamine hydrochloride) monolayers b-c dissolution of template core c-d loading of polyelectrolyte capsules with corresponding anions d-e precipitation of inorganic material from... 

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