Na0.5Bi0.5TiO₃:Y³⁺@PAN Nanofibers for Photocatalysis Using Synergetic Piezoelectric Effects

A series of Na0.5Bi0.5TiO3-based catalysts were synthesized by using the solvothermal route. The successful synthesis of catalysts was confirmed by various measurements. The influence of Y3+ doping on the band gap was revealed by the UV–visible absorbance spectra. Their photocatalytic, piezocatalytic, and piezo-photocatalytic activities were investigated by degrading methylene blue. The results show that the Y3+ doping can enhance the catalytic activity of Na0.5Bi0.5TiO3 due to the more efficient harvesting of light, and the catalytic activity can be further enhanced by the support of polyacrylonitrile nanofibers on account of the existence of more active sites. The reaction constants of Na0.5Bi0.485Y0.015TiO3 and Na0.5Bi0.485Y0.015TiO3@PAN in photocatalysis processes are 0.0075 and 0.0112 min–1, which is 1.23 and 1.84 times as many as that of Na0.5Bi0.5TiO3. In addition, the catalysts show higher catalytic activities when the catalysis is carried out at the operating condition including both simulated sunlight irradiation and ultrasonic vibration. The reaction constant of Na0.5Bi0.485Y0.015TiO3@PAN in piezo-photocatalysis is 0.0381 min–1, which is 3.09 and 6.77 times of photocatalysis and piezocatalysis. The enhanced activity results from suppression of charge carrier recombination. The radicals of •O2– and h+ play actual roles in the catalytic processes.