Unveiling the structure and composition of titanium oxide nanotubes through ion exchange chemical reactions and thermal decomposition processes

Abstract

In this paper we report the ion exchange reactions and the thermal decomposition of titanium oxide nanotubes, obtained by hydrothermal treatment of TiO2 and NaOH. Based on these results we propose a new composition for the as-prepared nanotubes as Na2Ti3O 7·nH2O. Our results also suggest that nanotube walls have structure similar to those observed in the layer of the bulk Na 2Ti3O7. Depending on how the washing process is performed on the nanotubes (water or acid solutions) the Na+ content can be modified via the exchange reaction of Na+ by H+. Thus, a general chemical formula was also proposed: Na2-xH xTi3O7·nH2O (0≤ x ≤2), x being dependent on the washing process. © 2006 Sociedade Brasileira de Química.