Fabrication of water-floating litchi-like polystyrene-sphere-supported TiO2/Bi2O3 S-scheme heterojunction for efficient photocatalytic degradation of tetracycline

Abstract

The exploration of advanced photocatalysts for antibiotic degradation is critical, but it remains a challenge due to the lack of rational structural design and in-depth insights into molecular oxygen activation. Water-floating photocatalysts could be one of the best choices owing to their technical features in terms of reasonability and efficiency involving a high oxygenation of photocatalyst surface, fully solar irradiation, and simple recycling and reuse. Herein, a floatable litchi-like architecture of a polystyrene-sphere-supported TiO₂/Bi₂O₃ (PS@TiO₂/Bi₂O₃) S-scheme heterojunction was skillfully constructed and evaluated for photodegradation of model tetracycline (TC) antibiotics. By integrating the advantages of floatability and S-scheme, the TC removal rate of the optimal PS@TiO₂/Bi₂O₃-0.4 catalyst can reach 88.4% under 1 h illumination, which is higher than that of pristine Bi₂O₃ (60.8%) and PS@TiO₂ (40.1%). Moreover, PS@TiO₂/Bi₂O₃-0.4 exhibits high recyclability and stability, and there is no significant loss of activity after five cycles of repeated use. With the aid of liquid chromatography–mass spectrometry analysis and density functional theory calculations, a reasonable degradation pathway for TC was proposed. The present work provides a recyclable and efficient approach for the photodegradation of TC, expecting to guide the innovative exploitation of other environmental systems.