Ti3C2 MXene nanosheet/TiO2 composites for efficient visible light photocatalytic activity

In the present work, we report a high activity Ti3C2 MXene nanosheet/TiO2 (Ti3C2/TiO2) composite photocatalyst synthesized by a solvent-thermal method using tetrabutyl titanate (Ti(OBu)4) as Ti source and HF as assistant. The Ti3C2/TiO2 composites were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV–Vis spectroscopy (UV–vis), fluorescence spectrometer (PL) and N2 adsorption-desorption. The photocatalytic performance of the Ti3C2/TiO2 composites was explored for the degradation of rhodamine B (RhB) under visible light irradiation. The results showed that more highly-active (001) crystal surfaces of TiO2 were exposed in the Ti3C2/TiO2 composites assisted by HF. The composite consisted of TiO2 microspheres and multilayer Ti3C2 exhibited optimal photocatalytic performance with relatively large specific surface area, large photocurrent and much lower impedances as compared to commercial TiO2 (P25) and pure TiO2. The optimized sample exhibited a degradation rate of 93.7% in 60 min, which was 20.5-fold higher than that of P25. The addition of the Ti3C2 effectively increased the lifetimes of the Ti3C2/TiO2 composites and suppressed the recombination of the electron-hole pairs. The density functional theory (DFT) calculations also revealed that the photogenerated electrons in the composites flowed from TiO2 to Ti3C2. The Schottky barrier at the TiO2–Ti3C2 interfaces effectively inhibited the electronic reflow to TiO2. The as-developed new Ti3C2-based complex with high photocatalytic activity under visible light irradiation might have effective and feasible application in the treatment of dye-containing wastewater.