TiO2 nanotubes fabricated by electrochemical anodization in molten o-H3PO4-based electrolyte: Properties and applications

초록

Self-organized TiO2 nanotubes (NTs) can be formed by elec-trochemical anodization. Anodization is generally performed in aqueous or organic electrolytes containing halogen ions, such as Cl- and F-. However, these electrolytes lead to less ordered structures or carbon remnants, thus suppressing the electrical properties and limiting the applications. To overcome these limitations, new anodization approaches were performed in carbon-free electrolyte-based electrolyte. In this review, we summarizes the short history of TiO2 NTs, general mecha-nisms of growing NTs, properties, and applications of classic TiO2 NTs. Then, a new-generation of anodization approach conducted in molten orhto-phosphoric acid is elucidated based on anodization parameters, concluding the optimized condition to form highly ordered TiO2 NT arrays. Finally, the review ad-dresses further modifications such as heat-treatment, noble metal deposition, thermal dewetting, and double anodization to enhance the optical and electrical properties for use in various applications.

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