Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.

TiO2 nanotubes: synthesis and applications.

Nanotubes composed of various materials such as carbon, boron nitride, and oxides have been studied recently. In this report, the discovery of a new route for the synthesis of a nanotube made of titanium oxide is presented. Needle-shaped TiO2 crystals (anatase phase) with a diameter of ≈8 nm and a length of ≈100 nm were obtained when sol−gel-derived fine TiO2-based powders were treated chemically (e.g., for 20 h at 110 °C) with a 5−10 M NaOH aqueous solution. It was found by observation using a transmission electron microscope that the needle-shaped products have a tube structure. The TiO2 nanotubes have a large specific surface area of ≈400 m2·g-1. TiO2 nanotubes obtained in the present work are anticipated to have great potential for use in the preparation of catalysts, adsorbants, and deodorants with high activities, because their specific surface area is greatly increased. If metallic-, inorganic-, or organic-based materials can be inserted into the TiO2 nanotubes, novel characteristics such as electr...

Formation of titanium oxide nanotube

We report on the microstructure and dynamics of electron transport and recombination in dye-sensitized solar cells (DSSCs) incorporating oriented TiO2 nanotube (NT) arrays. The morphology of the NT arrays, which were prepared from electrochemically anodized Ti foils, were characterized by scanning and transmission electron microscopies. The arrays were found to consist of closely packed NTs, several micrometers in length, with typical wall thicknesses and intertube spacings of 8−10 nm and pore diameters of about 30 nm. The calcined material was fully crystalline with individual NTs consisting of about 30 nm sized crystallites. The transport and recombination properties of the NT and nanoparticle (NP) films used in DSSCs were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. While both morphologies display comparable transport times, recombination was much slower in the NT films, indicating that the NT-based DSSCs have significantly higher charge-collection efficiencies than...

Enhanced Charge-Collection Efficiencies and Light Scattering in Dye-Sensitized Solar Cells Using Oriented TiO2 Nanotubes Arrays

A review on highly ordered, vertically oriented TiO2 nanotube arrays: Fabrication, material properties, and solar energy applications

We report a new method for the synthesis of titanium oxide (TiO2) nanotubes. When anatase-phase- or rutile-phase-containing TiO2 was treated with an aqueous solution of 5–10 M NaOH for 20 h at 110 °C and then with HCl aqueous solution and distilled water, needle-shaped TiO2 products were obtained (diameter ≈ 8 nm, length ≈ 100 nm). The needle-shaped products are nanotubes with inner diameters of approximately 5 nm and outer diameters of approximately 8 nm. The formation mechanism of titania nanotubes is discussed in terms of the detailed observation of the products by transmission electron microscopy: the crystalline raw material is first converted to an amorphous product through alkali treatment, and subsequently, titania nanotubes are formed after treatment with distilled water and HCl aqueous solution.

Titania Nanotubes Prepared by Chemical Processing

Titania Nanotubes Prepared by Chemical Processing.

TiO2-based powders doped with a small amount of SiO2 were prepared by a sol-gel method and subsequently were heated to precipitate fine anatase crystals. Although the obtained powders have large specific surface areas (≈200 m2 · g−1), they showed poorer activity in a photocatalytic property than the undoped TiO2 powders which have the area of 50 m2 · g−1. The SiO2-doped TiO2 powders were treated chemically with aqueous NaOH. Infrared reflection spectra showed that the treatment reduced the amount of SiO2 in the powders. The photocatalytic property of the powders was extremely improved by the treatment, and the powders showed higher activity than the undoped TiO2 powders.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400038851

Preparation of tio2-based powders with high photocatalytic activities

PROBLEM TO BE SOLVED: To produce a crystal titania that has an increased specific surface area and improved activity per unit volume when used for UV absorbers, shielding materials, absorbents and optically active catalysts, and is also useful for carriers of metal catalysts, and functional and magnetic materials by treating crystal titania with an alkali to make nanotubes of the crystal form of titania. SOLUTION: This titanium of 5 to 100-nm dia nanotubes is produced by forming a sol of titanium dioxide by a gas-phase process that hydrolyzes titanium ores, such as anatase, rutile and brookite, under heating, and calcines the obtained hydrated titanium dioxide at 800-850°C, or a liquid-phase process that makes Till. contact with O 2 and H 2 , or a sol-gel process using a titanium alkoxide, such as Ti(OR) 4 , adding a catalyst to the sob so as to gel, calcining the gel to obtain titania powder of 2-100nm in particle size, immersing the titania powder in an aqueous 13-65wt.% sodium hydroxide solution at 18-160°C for 1-50h in a closed vessel for alkali treatment of the titania powder to obtain titania of the nanotube form of 5-80nm diameter as shown by the model diagram, and then subjecting the titania to heat treatment where necessary. COPYRIGHT: (C)1998,JPO

Masayoshi Hiramatsu

Papers

Formation of titanium oxide nanotube

Titania Nanotubes Prepared by Chemical Processing

Titania Nanotubes Prepared by Chemical Processing.

Preparation of tio2-based powders with high photocatalytic activities

Crystal titania and its production