Surface -O terminated urchin-like TiO2/Ti3C2O (MXene) as high performance photocatalyst: Interfacial engineering and mechanism insight

The surface groups of MXene act as a decisive role on the performance of MXene-based photocatalysts. In this work, TiO2 nano-whiskers were grown in-situ on Ti3C2Tx, through a hydrothermal and post-heat treatment process, meanwhile, the surface groups of Ti3C2Tx were unified -O adsorption. The as-prepared urchin-like TiO2/Ti3C2Ox composite have efficient activity for photocatalytic hydrogen evolution and degradation of levofloxacin (LEV). The optimized hydrogen evolution reaction (HER) performance reached 346.8 μmol g-1 h−1, and the apparent quantum yield at 313 nm was 7.67%. Its hydrogen production performance and degradation rate of LEV were 9.7 and 7.7 folds higher than those of pure TiO2, respectively. The -O terminated Ti3C2Ox achieving a work function about 0.3 eV larger than TiO2, as both DFT calculation and UPS measurement depicted. Therefore, the photogenerated e-/h+ were separated at the TiO2/Ti3C2Ox interface via Schottky junction, a large amount of e- was enriched on Ti3C2Ox, which enabled the photocatalyst with remarkable charge separation and photocatalytic performance. Meanwhile, the reaction pathways of TiO2/Ti3C2Ox photocatalytic HER and LEV degradation/mineralization were carefully investigated. This study underlines the significance of surface groups on photocatalysts composed of MXenes, and sheds light on the new approach to the rational design of high-efficiency MXene-based photocatalysts.