Novel One-Dimensional Lepidocrocite Titanium-Oxide Nanofilaments—Synthesis, Characterization and Superior Dye Adsorption Properties

This study introduces a novel class of one-dimensional lepidocrocite titanium-oxide-based nanofilaments (1DLs), synthesized through a cost-effective and scalable solution-precipitation technique conducted under ambient conditions. The synthesis involves reacting titanium-based precursor powders, specifically TiB, TiC, Ti₅Si₃, or TiN, with quaternary ammonium hydroxide solutions, such as tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH), at 80°C over 3-4 days. X-ray diffraction, density functional theory, and transmission electron microscopy analyses revealed that the building blocks are 1D nanofilaments with cross-sectional dimensions of approximately 5×7 Ų. These nanofilaments stack along the [020] direction and grow along the [100] direction. They can form pseudo-2D structures when filtered or non-agglomerating semi-spherical and porous mesoporous particles (PMPs) upon washing and drying. The bandgap (BG) of these nanofilaments is high, ranging from 3.8 to 3.9 eV, due to size confinement. The pronounced adsorption capability of these nanofilaments was demonstrated by their ability to absorb and degrade organic dyes. For instance, in the case of Rhodamine 6G, TEA-1DL achieved up to a 65% reduction after 30 minutes in the dark, surpassing the performance of any existing TiO₂ materials.