Study on composition, structure and formation process of nanotube Na2Ti2O4(OH)2

A nanotube material is obtained by the reaction of polycrystalline TiO2 with concentrated NaOH solution for 20 h at 110 °C. From the contents of Na, Ti and the structural water determined, it is concluded that the nanotube material is Na2Ti2O4(OH)2, rather than TiO2, TiOx or H2TiO3. After treating with an HCl solution of pH 1, nanotube Na2Ti2O4(OH)2 can be converted to nanotube H2Ti2O4(OH)2. The crystalline structure of such nanotube materials belongs to an orthorhombic crystalline system. TEM results indicate that nanotube Na2Ti2O4(OH)2 is formed in the reaction stage of TiO2 with concentrated NaOH solution. The formation process is discussed.