Activating the photocatalytic activity of insulator barium silicate: A liquid-phase alkalized tetracycline photosensitizer and its self-destruction

• The insulator barium silicate (BSO) was used to efficiently degrade tetracycline. • The alkalization of tetracycline to the tetracycline lactone isomer (TCL) was first considered on the BSO surface. • The Lewis acid-base interaction constitutes the electron transport channel between BSO and TCL. • In the solid-liquid phase system, tetracycline is effectively degraded after activating the catalytic activity of BSO. Breaking through the inherent thinking, activating insulators with abundant and economical sources as photocatalysts to promote the practical application of photocatalysis has attracted attention. Herein, an insulator photocatalyst barium silicate (BSO) was successfully prepared by the hydrothermal method, and a solid-liquid photocatalytic reaction system combining solid-phase photocatalyst with liquid-phase antibiotic photosensitizer was constructed. In this reaction system, the insulator BSO achieved excellent photocatalytic activity, and the degradation of 30 mg/L tetracycline reached 93.2% after 12W LED illumination for 2h. The mechanism of tetracycline as a liquid-phase photosensitizer to activate the photocatalytic activity of BSO was explored. Lewis acid-base interaction not only alkalizes tetracycline to expand BSO light absorption, but also constitutes an electron transport channel between the BSO and alkalization tetracycline to facilitate the separation of photogenerated carriers. Alkalized tetracycline as a photosensitizer improves the response of BSO to visible light, and is decomposed by active substances such as 1 O 2 and ·O 2 − , thereby purifying the water body. This work reveals for the first time the mechanism of action of antibiotic photosensitizers to activate the photocatalytic activity of insulators, and provides a new perspective for the activation and development of insulators in photocatalysis.