Template-based synthesis methods

Covalent functionalization is accomplished by chemically attaching molecules to the CNT surface. In general, CNTs that lack defect sites need to undergo processes, such as sonication, add treatment, electrochanical oxidation, or plasma treatment to actually activate their surface aud provide hydrophilic surface functional groups for covalent attachment. CNTs and CNFs that have defect sites, such as those grown from template-based synthesis methods, will have some binding sites but will often require a degree of surface activation. 

Template-Based Synthesis Template directed synthesis represents a convenient and versatile method for generating ID nanostructures. In this technique, the... 

One-dimensional (1-D) nanosbuctures (b) are composed mainly of nanowires, nanorods and nanobelts. Spontaneous growth, template-based synthesis and electrospinning are considered bottom-up approaches, while lithography is a top-down technique [7, 84]. Two-dimensional (2-D) nanostructures (c) involve thin films, which have been the object of intensive study for almost a century and for which many methods have been developed and improved. 

In addition to these solution-based synthesis methods, uniform spherical particles of surfactant templated silicas and many other inorganic oxides have been prepared via drying of aerosol droplets of inorganic precursor with surfactant in a volatile solvent.This formation method is discussed in more detail in Section 2.7.3. 

A variety of solution methods such as seed-assisted growth, template-based synthesis, polyol method, solvothermal method and oriented attachment have also been developed for the synthesis of one-dimensional nanostructures. Here we will present various examples of the nanowires including metals, oxides, chalcogenides and pnictides with different synthetic methods. 

Huczko A (2000) Template-based synthesis of nanomaterials. Appl Phys A 70 365-376 Ihokura K, Watson J (1994) The stannic oxide Gas sensor principle and application. CRC, Boca Raton, EL Ivanovskaya M (2000) Ceramic and film metal oxide sensors obtained by sol-gel method structural features and gas-sensitive properties. Electron Technol 33(1/2) 108-112 Janata J (1989) Principle of chemical sensors. Plenum, New York, NY... 

The formation of open and porous structures with extremely large surface area is of high technological significance, because this structure type is very suitable for electrodes in many electrochemical devices, such as fuel cells, batteries and sensors [1,2], and in catalysis applications [3]. The template-directed synthesis method is most commonly used for the preparation of such electrodes. This method is based on a deposition of desired materials in interstitial spaces of disposable hard template. When interstitial spaces of template are filled by deposited material, the template is removed by combustion or etching, and then the deposited material with the replica structure of the template is obtained [4, 5]. The most often used hard templates are porous polycarbonate membranes [6, 7], anodic alumina membrane [8-10], colloidal crystals [11, 12], echinoid skeletal stractures [13], and polystyrene spheres [14, 15]. 

Che, G., Lakshmi, B.B., Martin, C.R., and Fisher, E.R. Chemical vapor deposition based synthesis of carbon nanotubes and nanofibers using a template method. Chem. Mater. 10, 1998 260-267. 

Mixed alkoxide method. Hydrothermal synthesis using tetraethylorthosilicate (TEOS) as the source of Si, tetraethyltitanate (TEOT) as the source of Ti, tetrapropylammonium hydroxide (TPAOH) as structure directing agent (template), base and distilled water... 

Che G, Lakshmi B, Martin C, Fisher E, Ruoff R (1998) Chemical vapor deposition based synthesis of carhon nanotuhes and nanofi-hers using a template method. Chem Mater 10 260-267. 

The Co(salophen) complex encapsulated in zeolite was prepared by two different methods. The flexible ligand method involves the diffusion of the Schiff base ligand into the zeolite, where upon complexation with the Co ion becomes too large to exit. However, this method was not useful for the preparation of Co(salophen)/zeolite, because the catalyst was not active in the oxidation reaction. For this reason the synthesis, originally used for the preparation of the free Co(salophen) complexes was modified and the principles of template synthesis method was used to prepare the Co(salophen)/zeolite catalyst. 

The nanostructures can be deposited into the nano-pores by electrodeposition or sol-gel deposition methods. The advantages of being low cost and repeatable, together with their potential compatibility with silicon technologies, make these nanostructure synthesis procedures interesting. Despite its simplicity, template-based growth is characterized by the production of polycrystalline nanowires, which can limit their potential for both fundamental studies and applications. 

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