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

Abstract

A series of N-TiO 2 /Ti 3 C 2 composites are constructed via ultrasonically treating pre-synthesized N-TiO 2 and Ti 3 C 2 . Improved sonophotocatalytic activity is demonstrated by the tests of contaminant degradation and nitrogen fixation. • The N-TiO 2 /Ti 3 C 2 composites are constructed under ultrasound irradiation. • The intimate interfacial contact is verified by a series of characterizations. • Improved sonophotocatalytic degradation and nitrogen fixation are confirmed. • The synergic effect of N 2p doping and Ti 3 C 2 coupling contribute to the enhancement. • The order of catalytic behavior was sonophotocatalysis＞sonocatalysis＞photocatalysis. Herein, a series of N-TiO 2 /Ti 3 C 2 (N-TTC x ) composites are constructed via ultrasonically treating pre-synthesized N doped TiO 2 and Ti 3 C 2 at room temperature. The intimate contact between N-TiO 2 and Ti 3 C 2 is verified by the transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. And, the N-TTC 0.06 composites exhibit the best sonophotocatalytic performance, which is 1.9 times and 8.8 folds higher than that of TiO 2 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-TTC 0.06 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-TiO 2 /Ti 3 C 2 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 Ti 3 C 2 , which are demonstrated by UV–vis absorption spectra, photoelectrochemical tests, Nyquists plots, and Mott-schottky plots. This study confirms that the designed N-TiO 2 /Ti 3 C 2 composites exhibit great potential application in sonophotocatalytic pollutant degradation and nitrogen fixation.