(627g) Application of TiO2-Ti3C2Tx Nanowires in Aqueous-Phase Photocatalytic Degradation

TiO₂ is a low-cost and environmentally benign photocatalyst that can be applied for the degradation of aqueous phase pollutants. The challenge with TiO₂ photocatalysis includes its wide bandgap energy (3.2 eV), visible light inactivity, and rapid electron-hole recombination. Nanowires morphology for TiO₂ can enhance the surface area and improve geometric compatibility when coupling with other structures. In this study, TiO₂ nanowires were synthesized by a hydrothermal technique whilst simultaneously coupled with different quantities of Ti₃C₂T_x MXene (5, 12, and 20 mg). The photocatalysts were characterized by Photoluminescence spectroscopy (PL), UV-vis Spectroscopy, X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Raman spectroscopy and Transmission Electron Microscopy (TEM). The successful etching of Ti₃C₂T_x using NH₄HF₂ was determined by XRD, XPS, and SEM. TiO2wire diameter of the TiO₂ was determined by TEM to be around 13.84 ± 2.92 nm. Tauc plots showed that TiO₂ nanowires had an indirect bandgap of 3.2 eV and the TiO₂ coupled with MXenes had bandgaps of 2.5-2.9 eV. PL spectra revealed a lesser intensity of photoluminescence (due to charge carrier recombination) in the samples containing MXenes. The TiO₂-MXene-12mg sample showed the best performance of MB degradation in the liquid phase at 88% efficiency and a rate constant of 0.0308 min^-1. TiO₂-Ti₃C₂T_x forms Schottky junctions and the MXene serves as an electron reservoir thereby reducing recombination. The study revealed that coupling Ti₃C₂T_x sheets with TiO₂ nanowires can reduce the bandgap of the photocatalyst, reduce electron-hole recombination, and ultimately improve the photocatalytic performance in the liquid phase.