Modulating energy band structure of CsPbBr3@TiO2 composites for enhanced photocatalytic and anti-superbacterial performance

Oxide-based photocatalysts are widely used for antibacterial and water treatment. However, they are limited by their wide bandgaps, which restrict the activation to specific wavelengths. Efforts are being done to enhance the reactivity, including doping with different elements, combining with other semiconductors, and creating heterogeneous structures. In this study, a composite photocatalyst was developed by forming CsPbBr₃@TiO₂, a heterostructure using CsPbBr₃ quantum dots and TiO₂, where the induced intermediate states narrow the bandgap, extending the light absorption range into the visible spectrum. Photocatalytic applications in dye degradation and removal of superbacteria utilize this property.

CsPbBr₃@TiO₂ composite showed significant degradation efficiency for rhodamine B and Reactive Black 5 under ultraviolet (UV) and visible-light irradiation. While anatase TiO₂ nanoparticles showed a degradation efficiency of up to 21.1 % after 1 h of light irradiation, the CsPbBr₃@TiO₂ composite showed a degradation efficiency of up to 95.3 %, indicating excellent water purification. Furthermore, in an optical density measurement to analyze the antibacterial activity against prominent superbacteria such as Staphylococcus aureus, Enterococcus faecalis, and Enterococcus faecium, recently been identified as resistant to almost all antibiotics due to drug abuse, the CsPbBr₃@TiO₂ composite showed a reduction of 84.9 %, while the anatase TiO₂ nanoparticles showed a 42.5 % reduction, indicating up to a 2-fold higher antimicrobial activity. These results indicate that the CsPbBr₃@TiO₂ composites possess outstanding photocatalytic efficiency for environmental applications and suggest an easy and rapid method for the extensive production of highly responsive visible-light photocatalysts for water purification and biomedical applications.