Synthesis and characterization of layered oriented hydrogen titanate micro-tube films

摘要

Continuous and uniform films of oriented hydrogen titanate tubes with diameters, c.a. 200 nm, were prepared directly via porous anodic aluminum oxides (AAO) templates without any further removal of templates. Simple impregnation method was applied with aqueous solution titanium tetrafluoride (TiF₄) as the precursor to form the titania sol-gel. Scanning electron microscope (SEM) results show that the films are uniform, tubes highly oriented and even in length, diameter and morphology. Hydrogen trititanate (H₂Ti₃O₇) phase is proved by X-ray diffraction (XRD) patterns. Layered films of oriented tubes are fabricated when impregnation time is well controlled. The formation mechanism is drawn with the help of energy dispersion spectra (EDS). Due to the existence of F −, the hydrolysis of Ti4+ is relatively slow along inner channel walls of AAO, which eventually forms compact tube arrays. The solubility among different parts of AAO template is of big difference in acidic surrounding. Layered films of oriented tubes are, therefore, fabricated when impregnation time is well controlled. The channel size of the AAO template takes control in deciding the pore size of the titania micro-tubes and reaction time, the length of the tubes.