Preparation of TiO2–(B) by microemulsion mediated hydrothermal method: effect of the precursor and its electrochemical performance

Synthesis of TiO2–(B) bronze was carried out by hydrothermal method using different precursors: (a) commercial anatase, (b) amorphous TiO2 prepared by O/W microemulsion method and (c) oil-in-water (O/W) microemulsion with freshly prepared amorphous TiO2. It is important to highlight this is the first report of the preparation of TiO2–(B) using an O/W microemulsion as a precursor. The effect of precursor type on the resulting TiO2 nanostructures, namely, their structural and morphological features were studied using X-ray diffraction, thermal analysis (TGA–DTA), Brunauer–Emmett–Teller, Raman spectroscopy and scanning electron microscopy (SEM–EDX). From commercial anatase powder, amorphous TiO2 ME and O/W microemulsion ME238 (NaOH/TiO2 molar ratio 238), biphasic nanoribbons were obtained: TiO2–(B) (88–92%) and anatase (8–12%). While from the O/W microemulsion ME30 (NaOH/TiO2 molar ratio 30) only anatase phase was obtained. The material with higher TiO2–(B) phase content, showed an increase in its reversible capacity, thus the crystalline nature of the precursor as well as the textural properties contribute to the electrode performance. Materials synthesized from commercial anatase and amorphous TiO2 ME exhibited similar charge retention (86–87%) despite the slight difference in reversible capacity, 210 and 180 mAh/g, respectively. It is noticed that TiO2–(B)–AME (prepared from amorphous TiO2 ME) exhibited the lowest capacity loss, e.g. the highest reversibility.