Hierarchical ZnS layers-coated Ti3+-TiO2 nanostructures for boosted visible-light photocatalytic norfloxacin degradation

Self-doped Ti3+-TiO2 and amorphous ZnS layers-coated Ti3+-TiO2 nanostructures were successfully fabricated for via a calcination-ultrasonic synthesis strategy for organic pollutant degradation under visible-light illumination. The experimental results revealed that the synthesized Ti3+-TiO2 clusters displayed efficient visible-light absorption and photocatalytic performance. It was also found that amorphous ZnS layers were formed on the coral-like Ti3+-TiO2 clusters via an ultrasonic synthesis method, and the strongly combined interfaces greatly boosted the charge separation between ZnS layers and self-doped Ti3+-TiO2 clusters. The synthesized Ti3+-TiO2@ZnS-15% heterojunction presented the highest photocatalytic activity with a rate constant of 0.03197 min−1, approximately 9.87 times of commercial TiO2. In addition, the prepared Ti3+-TiO2@ZnS composites also exhibited highly boosted photocatalytic performance towards ciprofloxacin and tetracycline degradation under visible-light illumination compared with those of commercial TiO2, Ti3+-TiO2, and ZnS samples. Finally, the norfloxacin degradation pathways and visible-light photocatalytic mechanism over nanostructured Ti3+-TiO2@ZnS heterojunctions were suggested.