Unique Kinetics Feature and Excellent Photocatalytic Performance of Tetracycline Photodegradation Using Yolk-Shell Tio2@Void@Tio2:Eu3+

Abstract

The multifunctional yolk-shell TiO2@void@TiO2:Eu3+ calcined at different temperatures were successfully designed and fabricated by sacrificial template method for the photodegradation of tetracycline. The impacts of yolk-shell structure and thermal treatment temperature on the photoluminescence and photocatalytic properties have been investigated in detail. The results of photoluminescence show that sample calcined at 800 °C exhibits the strongest red emission. The photocatalytic efficiency for tetracycline reached 96.06% in 50 min by sample calcined at 900 °C. The half-life time for decomposing tetracycline turns out to be even 2 min. The kinetics fitting curves consist of two straight lines with different slopes, which is reported for the first time so far. Furthermore, ∙O2− radicals contribute most to the photocatalytic process. Meanwhile, the photocatalytic mechanism and possible photodegradation pathway of tetracycline were proposed. Compared with the double-shell samples, the yolk-shell samples show a high photodegradation rate within 5 min and unique kinetics feature. The analysis of photocatalytic kinetics provides a new idea for studying the photocatalysis mechanism. The rapid tetracycline photodegradation by the yolk shell material also provides new strategies for practical water purification.

Keywords: TiO2 yolk-shell structure, tetracycline, photoluminescence, photocatalysis, photodegradation pathway and kinetics