Structural resistance of chemically modified 1-D nanostructured titanates in inorganic acid environment

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• 作者：Bojan A. Marinkovic ; Yann C. Fredholm ; Edisson Morgado Jr. ; Paula M. Jardim ; Fern ; o Rizzo
• 关键词：Titanate nanotubes and nanobelts ; Hydrothermal synthesis ; Acid aging ; TEM ; XRD
• 刊名：Materials Characterization
• 出版年：2010
• 出版时间：October 2010
• 年：2010
• 卷：61
• 期：10
• 页码：1009-1017
• 全文大小：1322 K

文摘

Sodium containing one-dimensional nanostructured layered titanates (1-D NSLT) were produced both from commercial anatase powder and Brazilian natural rutile mineral sands by alkali hydrothermal process. The 1-D NSLT were chemically modified with proton, cobalt or iron via ionic exchange and all products were additionally submitted to intensive inorganic acid aging (pH = 0.5) for 28 days. The morphology and crystal structure transformations of chemically modified 1-D NSLT were followed by transmission electron microscopy, powder X-ray diffraction, selected area electron diffraction and energy dispersive spectroscopy. It was found that the original sodium rich 1-D NSLT and cobalt substituted 1-D NSLT were completely converted to rutile nanoparticles, while the protonated form was transformed in a 70 % –30 % (by weight) anatase–rutile nanoparticles mixture, very similar to that of the well-known TiO₂-photocatalyst P25 (Degussa). The iron substituted 1-D NSLT presented better acid resistance as 13 % of the original structure and morphology remained, the rest being converted in rutile. A significant amount of remaining 1-D NSLT was also observed after the acid treatment of the product obtained from rutile sand. The results showed that phase transformation of NSLT into titanium dioxide polymorph in inorganic acid conditions were controllable by varying the exchanged cations.

Finally, the possibility to transform, through acid aging, 1-D NSLT obtained from Brazilian natural rutile sand into TiO₂-polymorphs was demonstrated for the first time to the best of authors' knowledge, opening path for producing TiO₂-nanoproducts with different morphologies through a simple process and from a low cost precursor.