Metal oxide nanotubes

Thus far, only metal-oxide nanotubes have been synthesized by this process. Whereas crystalline nanotubes were obtained from 2D (layered) oxides, various 3D oxide compounds resulted in semicrystalline or amorphous nanotubes, only. In principle, this kind of process could be extended to the synthesis of nanotubes from chalcogenide and halide compounds in the future. 

Metal oxide nanotubes have been synthesized by a diverse variety of fabrication routes. For example titania nanotubes, and nanotube arrays, have been produced by deposition into a nanoporous alumina template [48-51], sol-gel transcription using organo-gelators as templates [52,53], seeded growth [54], hydrothermal processes [55-57] and anodic oxidation [58-65]. 

Metal oxide nanotubes containing bundles of gel fiber... 

Fig. 5.1 Template (organogelator) synthesis of metal oxide nanotubes.

Hanabusa K, Numazawa T, Kobayashi S, Suzuki M, Shirai H (2006) Preparation of metal oxide nanotubes using gelators as structure-directing agents. Macromol Symp 235 52-56... 

Nanotubes of MoS2, WS2 and a few other layered materials are single-crystalline in the sense that the layers run through the entire structure. Some of the chalcogenide nanotubes are, however, polycrystalline, the nanotubular form being produced by an aggregation of nanoparticles, just as in some of the metal oxide nanotubes. 

Title Metal Oxide Nanotube and Process for Production Thereof... 

Spiral shaped hollow nanofibers were formed from the reaction of p-aminophenyl-p-D-glucopyranoside and p-dodecanoylaminophenyl-p-o-glucopyranoside with excess tetraethoxysilane. The diameter distributions of these tubes ranged from 1 to 2 nm and from 3 to 7 nm. Metal oxide nanotubes derived from this process displayed excellent hydrogen adsorption and storage capacity for potential use in hydrogen-powered vehicles. 

Three milhgrams apiece of the Step 1 and Step 2 products were dissolved in 10 ml of water and 1 ml of methanol by heating the solution to 70°C. This mixture was then treated with tetraethoxysUane (20 mg) followed by benzylamine (6 mg). A gel that formed during gradual cooling of the mixture stood uninterrupted at ambient temperature for seven days. The sample was then sintered in a nitrogen gas atmosphere first for two hours at 200°C and then for four hours at 500°C, and metal oxide nanotubes were isolated. 

The metal oxide nanotubes were analyzed by scanning electron microscopy and field emission scanning electron microscopy, which indicated the presence of a double hehx. 

How would you synthesize metal oxide nanotubes, using a sacrificial template Cite any related precedents from the literature. 

When HRTEM is used for examining nanoparticles of oxides, in which the proportion of surface area greatly increases, most structural information concerns the surface. For example, HRTEM images of core-shell quantum dots can show the shell structure and its thickness directly. HRTEM images of metal oxide nanotubes can also be regarded as surface profile images. The appHcation of TEM in nanomaterials will be further discussed below. 

Metal Oxide Nanotube Solid Acid A one-dimensional metal oxide, titanium nanotube was reported as a solid add catalyst [56]. Protonated titanium nanotubes were synthesized by the hydrothermal treatment of bulk titanium oxide in high pH solution, followed by proton exchange. The nanotubes have high surface... 

M. Knez et al. showed the application of atomic layer deposition, a gas-phase thin film deposition process, to biological macromolecules (tobacco mosaic virus and ferritin), which are frequently used as templates in nanoscale science, and the possibility to fabricate metal oxide nanotubes and thin films with embedded... 

Allam, N.K., Shankar, K., Grimes, C.A. A general method for the anodic formation of crystalline metal oxide nanotube arrays without the use of thermal annealing. Adv. Mater. 20, 3942-3946 (2008)... 

RuOj nanotubes have been synthesized by the thermal decomposition of Ru3(CO)j2 inside anodic alumina membranes [248]. Transition metal oxide nanotubes have been prepared in water using iced hpid nanotubes as the template [249]. Self-assembled cholesterol derivatives act as templates as well as catalysts for the sol-gel polymerization of inorganic precursors to give rise to double-walled tubular structures of transition metal oxides [250]. Hydrothermal synthesis of single-crystalline y-Fefi ... 

Figure 8.13 Schematic illustration of the fabrication for metal oxide nanotubes. The template is coated with a passivation layer that enables selective deposition onto the inner pore walls after chemical etching, the free-standing nanotubes are obtained [126]. Reproduced from Ref [126], with kind permission ofWiley-VCH.

Cochran, R.E., Shyue,).-). and Padture, N.P. (2007) Template-based, nearambient synthesis of crystalline metal-oxide nanotubes, nanowires and coaxial nanotubes. Acta Materialia, 55,... 

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