Role of Water in the Transformation of Protonated Titanate Nanoribbons to Anatase Nanoribbons

Transformation of layered protonated titanate (H2Ti3O7) nanoribbons to anatase nanoribbons under hydrothermal conditions is a catalyzed process where topotactic transformation and dissolution–recrystallization compete. In the present work, the transformation was achieved with sufficiently high thermal input, calcination, or catalysis when performed under hydrothermal conditions. X-ray diffraction and scanning and transmission electron microscopy combined with crystallography of product materials revealed that the success of catalysis depended on the suspension’s pH value as well on the counterions present in the reaction mixture. The process of the transformation from protonated titanate to anatase under hydrothermal conditions is explained for the reaction medium pH range of 1–13.7 with the aid of the ζ-potential of protonated titanate nanoribbons. Protonated titanate nanoribbons were stable under basic conditions, and their transformation to anatase nanoribbons depended on the counterions present in the...