Oxidation-driven auto-conversion of Ti3C2Tx MXene to TiO2 nanoparticles for photocatalytic applications

Ti3C2Tx MXene, a recently discovered 2D material, possesses unique properties; however, its lack of stability against oxidation poses a significant challenge to its application. This study leverages the auto-oxidation of Ti3C2Tx MXene to synthesize TiO2 (termed as m-TiO2) nanoparticles, addressing MXene susceptibility to oxidation as an advantage. This study enhances the utilization of remaining MXenes, minimizing waste and maximizing resource efficiency. The Ti3C2Tx MXene was allowed to oxidize in deionized water under ambient conditions for an extended period of one year, resulting in a transformation from dark black Ti3C2Tx MXene to milky white m-TiO2, indicating Ti3C2Tx MXene degradation. The size of the Ti3C2Tx MXene nanoflakes under investigation is ∼500 nm, while the resulting high surface area porous m-TiO2 nanoparticles have an average size of ∼40 nm. The transformation of Ti3C2Tx MXene into m-TiO2 nanoparticles was assessed through a combination of analytical techniques, including X-ray diffraction analysis (XRD), UV-Vis absorbance analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analysis. The specific surface areas (SSA) of 7.2 m2/g and 39.1 m2/g for Ti3C2Tx MXene and m-TiO2 nanoparticles, respectively, signify the presence of micro/nanopores in the latter. The m-TiO2 nanoparticles exhibit promising photocatalytic properties, efficiently degrading methylene blue (MB) dye under UV light.