S-Scheme BaTiO3/TiO2 heterojunctions: Piezophotocatalytic degradation of norfloxacin

The combination of light energy and mechanical energy is thought to be an effective way to manage environmental resources and create sustainable energy. In this study, thin-film catalysts compounded with photocatalytic material TiO2 and piezoelectric material BaTiO3 were successfully prepared by a simple hydrothermal method on glass sheets, avoiding the possibility of secondary contamination of powder catalysts. The synergistic effect of light and ultrasound enhanced the degradation of norfloxacin by heterojunction BaTiO3/TiO2. After 60 min, the norfloxacin degradation was 91.7 % complete, with a rate constant of 43 x 10-3 min(-1). This rate constant was 2.69 times higher than the rate constant for TiO2 at 16 x 10(-3) min(-1). The built-in electric field generated by ultrasound is thought to improve the catalytic and optoelectronic properties of the composite by separating photogenerated electrons and holes. In addition, the stability and general usability of the composites were investigated. The effects of norfloxacin concentration, solution pH, and anions on the experiments were also analyzed. Free radical trapping experiments were conducted on the composites to identify the active species. The results showed that h(+) and center dot OH were the main active species. In addition, it was determined that S-Scheme heterojunctions were likely involved in the catalytic process.