Direct synthesis of hydrogen fluoride-free multilayered TiC/TiO composite and its applications in photocatalysis.

TiC/TiO hybrids are environment-friendly and exhibit excellent photocatalytic and hydrogen-generating power characteristics. Herein, a novel single-step method is proposed for fabricating multilayer structures in which TiO, generated from (NH)TiF, wraps the TiC MXene by etching TiAlC with (NH)TiF. The optimal reaction conditions for the etching of TiAlC with (NH)TiF were systematically studied. The phase composition, morphology, and photophysical properties of the TiC/TiO hybrids were investigated using X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and UV-vis spectrophotometry. The thermal stability of the hybrids was investigated using thermogravimetric and differential thermal analyses. Along with the formation of TiC MXene, TiAlC reacted with (NH)TiF at 60 °C for 24 h to form hybrids surrounded by NHTiOF crystals. Subsequent reactions of these hybrids with HBO resulted in the conversion of NHTiOF crystals into TiO and eventually into TiC/TiO hybrids. Furthermore, the photocatalytic activity of the TiC/TiO hybrids was measured by monitoring the photodegradation of methylene blue under ultraviolet light, which showed that the photocatalytic activity of the TiC/TiO hybrids was higher than that of the commercial anatase TiO nanoparticles.