Low-Temperature Synthesis of Titanate Nanotubes in Aqueous KOH

Although hydrothermal alkaline treatment of TiO2 in a concentrated, aqueous solution of KOH usually results in the formation of solid fibrous titanates, analysis of the temperature dependence of Ti(iv) concentration in KOH solution and comparison of these data with that for NaOH solution suggests that, at low temperatures, the treatment of TiO2 with KOH may result in formation of titanate nanotubes. This result was confirmed by 12 days treatment of TiO2 in 10 mol dm–3 KOH at 56°C, resulting in the formation of nanotubular titanates with similar morphology to those produced in a shorter time at higher temperatures using NaOH. The mechanism of nanotube formation and the necessary conditions of nanotube phase formation are considered.