Structural Analysis of Colloidal Titania-Based Ribbons and Their Self-Assembly upon Drying

Abstract

Synchrotron-based small- and wide-angle X-ray scattering is used to elucidate the structure of low-dimensional lepidocrocite–titanate-based nanofilaments. In the colloidal state, they consist of quantum-confined 1D NFs, loosely associated into nanoribbons, one lepidocrocite sheet thick (about 4 Å), 30–40 Å wide (5–8 NFs), and more than 300 Å long. In the dry state, they reach a final state of extended sheets, stacked three to about twenty high, whose crystallinity increases with stack height, in parallel with a decrease in photocatalytic activity. These findings suggest a kinetic pathway for the self-assembly of initially 1D titanate nanoribbons into 2D and ultimately 3D structures, providing context for a recent body of work on these low-dimensional materials.