Improvement of sonocatalytic activity of TiO2 by using Yb, N and F-doped Er3+:Y3Al5O12 for degradation of organic dyes

In this study, several up-conversion luminescence agents (Er3+:Y3Al5O12, Er3+:Yb0.2Y2.79Al5O12, Er3+:Yb0.2Y2.79Al5N0.01O11.99, Er3+:Yb0.2Y2.79Al5F0.01O11.99 and Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98) were synthesized using sol-gel method. And then, the corresponding sonocatalyst (Er3+:Y3Al5O12/TiO2, Er3+:Yb0.2Y2.79Al5O12/TiO2, Er3+:Yb0.2Y2.79Al5N0.01O11.99/TiO2, Er3+:Yb0.2Y2.79Al5F0.01O11.99/TiO2 and Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites) were prepared by sol-gel coating process. The synthesized up-conversion luminescence agents and their coated composites were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). And that, the sonocatalytic activities were detected through the degradation of Azo Fuchsine (AF) dye in aqueous solution by UV-vis spectroscopy. Some key influences such as heat-treated temperature and heat-treated time on the sonocatalytic activity of Er3+:YbaY2.99−aNxFyAl5O12−x−y/TiO2 coated composite, as well as ultrasonic irradiation time and initial dye concentration on the sonocatalytic degradation were studied. The results showed that the doping of Yb, N and F into Er3+:Y3Al5O12/TiO2 significantly enhanced the sonocatalytic activity of Er3+:Y3Al5O12/TiO2 coated composite in the degradation of organic dyes. Particularly, Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites with 3:7 M ratio heat-treated at 550 °C for 60 min showed the highest sonocatalytic activity. At last, the experiments also indicated that the Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites has a good sonocatalytic activity to degrade other organic dyes under ultrasonic irradiation.