Search for: All records

Abstract Nanostructured titania, TiO₂, holds significant importance in various scientific fields and technologies for their distinctive properties and multipurpose characteristics. In this article, the facile, economical, and scalable synthesis of 1D lepidocrocite, 1DL, titania nanostructures derived from a water‐soluble Ti precursor, titanium oxysulfate (with oxidation of Ti⁺⁴) at temperature <100 °C under atmospheric pressure is discussed. Titanium oxysulfate with tetramethyl ammonium hydroxide, TMAH, is simply reacted to yield individual lepidocrocite titania‐based chain‐forming nanofilaments, NFs, 6 × 6 Ųin minimal cross‐section and aspect ratios of ≈20 1DLs. If only ethanol is used for washing, the 1DL self‐assemble into ≈10 µm, porous mesostructured particles, PMPs. If water is used, quasi‐2D sheets form instead. Characterization of the resulting powders showed them to be quite similar to those derived from TiB₂, and other water‐insoluble Ti precursors. The 1DL bandgap energies are ≈4 eV, due to quantum confinement. They adsorbed rhodamine 6G. The latter also sensitized the 1DLs and allowed for dye degradation using only visible light. Used as electrodes in supercapacitors, the 1DLs can be cycled over 1.6 V and result in high power densities (300 W kg⁻¹). Stronger birefringence started to appear in samples with concentrations >15 gL⁻¹indicating the formation of a liquid crystal phase. This new synthesis protocol enables the cheaper scalable production of 1DLs with significant implications across various fields. 

The novel material, one-dimensional lepidocrocite (1DL) titanate, is attracting industrial and scientific interest because of its applicability to a wide range of practical applications and its ease of synthesis and scale up of production. In this study, we investigated the CO2 adsorption capability and pore structures of 1DL freeze-dried and lithium chloride washed air-dried powders. The synthesized 1DL was characterized by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Using the constant-volume method, CO2 gas adsorption revealed that the 1DL exhibits type IV adsorption–desorption isotherms. The heats of adsorption obtained from the adsorption branches are lower than those obtained from the desorption branches. Brunauer–Emmett–Teller (BET) analysis, using N2 gas adsorption isotherms at 77 K showed that 1DL possesses 80.2 m2/g of BET specific surface area. Nonlocal density functional theory analysis indicated that two types of pores, meso-pores and ultramicro pores, exist in the 1DL freeze-dried powders. This work provides deep insights into the pore structures and CO2 adsorption mechanisms of 1DL powders. 

One-dimensional lepidocrocite, 1DL, titania, TiO2, is a recently discovered form of this ubiquitous oxide that is of interest in a variety of applications ranging from photocatalysis to water purification, among others. The fundamental building blocks of these materials are snippets (30 nm long) of individual 1DLs that self-assemble into nanobundle, NB, structures. These NBs can then be driven to self-assemble into quasi-two-dimensional, 2D, sheets, films, or free-flowing mesoscopic particles. Here, we use analytical atomic-resolution scanning transmission electron microscopy (STEM) and first-principles density functional theory (DFT) calculations to demonstrate that the arrangement of the neighboring NFs can be altered through ion exchange with Li, Na, and tetramethylammonium hydroxide (TMA) cations. Moreover, using cryogenic electron energy-loss spectroscopy (EELS), we show that the introduction of different ion species results in a change in the local occupancy of the TiO2 t2g and eg orbitals. Both experimental findings are predicted by ground-state energy simulations of two-dimensional lepidocrocite TiO2.