Ultrasonically synthesized N-TiO2/Ti3C2 composites: Enhancing sonophotocatalytic activity for pollutant degradation and nitrogen fixation

Herein, a series of N-TiO2/Ti3C2 (N-TTCx) composites are constructed via ultrasonically treating pre-synthesized N doped TiO2 and Ti3C2 at room temperature. The intimate contact between N-TiO2 and Ti3C2 is verified by the transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. And, the N-TTC0.06 composites exhibit the best sonophotocatalytic performance, which is 1.9 times and 8.8 folds higher than that of TiO2 for pollutant degradation and nitrogen fixation, respectively. What’s more, sonophotocatalytic degradation of pollutants and nitrogen fixation shows larger efficiency compared with that of photocatalysis and sonocatalysis, which is attributed to the synergistic effect between sonocatalysis and photocatalysis in the sonophotocatalytic process. Moreover, taking N-TTC0.06 for example, the three cycles of sonophotocatalytic degradation of Rh-B and nitrogen fixation as well as the unchanged X-ray diffraction before and after sonophotocatalytic nitrogen fixation all confirm the stable sonophotocatalytic behavior of N-TiO2/Ti3C2 composites. The improved sonophotocatalytic activity is attributed to the decrease of band gap by N 2p doping level and the separation/transfer improvement of photoinduced carriers by Ti3C2, which are demonstrated by UV–vis absorption spectra, photoelectrochemical tests, Nyquists plots, and Mott-schottky plots. This study confirms that the designed N-TiO2/Ti3C2 composites exhibit great potential application in sonophotocatalytic pollutant degradation and nitrogen fixation.