Study of the formation of mesoporous titania via a template approach and of subsequent Li insertion

Abstract

Mesostructured titania was prepared according to Rao et al. using dodecylamine as the amine template. X-Ray absorption spectroscopy was used to study changes in the Ti local coordination environment during formation of the mesoporous material—starting from the alkoxide precursor, followed by hydrolysis and condensation to form poorly crystallized anatase upon heat treatment. Neutral amine inhibits the formation of dimers prior to the hydrolysis reaction and gives rise to a more connected local structure. The Ti site is highly distorted, with a coordination environment ranging between O_h and D_4h symmetry. A higher surface area (up to 260 m² g⁻¹) results when acid washing is employed to remove the surfactant template, whereas a surface area of only 80 m² g⁻¹ is obtained when the template is removed by heat treatment. Li insertion proceeds via a pseudo-capacitive behavior in the presence of dodecylamine (DDA), whereas an anodic peak at 1.8 V vs. Li is present when the framework is condensed to form anatase. The incorporation of niobium atoms reinforces the structure, and the electrochemical behavior is more stable in cycling.