Sunlight-driven catalytic degradation of tetracycline by α-NaYF4@TiO2-Acac nanoparticles and the toxicity of intermediate products

Up-converting α-NaYF4@TiO2-Acac core-shell nanoparticles, synthesized via hydrothermal treatment and sol-gel coating, were used for photocatalytic degradation of a tetracycline solution under a solar simulator. The synthesized structures exhibited wide spectral response capability, enabling up to 90 % degradation within 6 h, at a photocatalyst concentration of 10 mg L−1. Highly reactive superoxide radicals (O2−) were found to be the major reactive species responsible for tetracycline photo-oxidation. The boosted generation of superoxide radicals is attributed to an additional energy transfer from the core to the shell, established through direct radiation-reabsorption process and Förster resonance energy transfer. The absence of toxicity in tetracycline intermediates, formed on photodegradation, suggests the potential of α-NaYF4@TiO2-Acac core-shell nanoparticles for application in wastewater treatment.