One-dimensional, titania-based lepidocrocite nanofilaments and their self-assembly

Summary

Water stable, one-dimensional (1D) materials are few and far between and none are titania based. Herein, we react inexpensive, water-insoluble titanium-based precursors—TiC, TiB₂, and TiN—with 25 wt % tetramethyl ammonium hydroxide aqueous solution at 80°C for 2 to 5 days under ambient pressures to produce short (≈100 nm) 1D titania-based lepidocrocite (1DL) nanofilaments (NFs) with minimal cross sections of ≈ 5 × 7 Ų. The NFs self-assemble into nanobundles that, in turn, self-assemble into ribbons/fibers micrometers long. The NFs also self-assemble into quasi-2D flakes that are more or less amorphous. With time, amorphous nanoparticles (NPs)—themselves composed of 1DL NFs attached to the 2D layers—form, rendering the system amorphous. Using X-ray diffraction, photoelectron, and Raman spectroscopies, selected area diffraction, and transmission and scanning electron microscopy, we conclude that, regardless of precursor chemistry, processing conditions, or final morphologies, the 1DL NFs are the essential building blocks in all microstructures.