TiO₂/Chlorophyll S-Scheme Composite Photocatalyst with Improved Photocatalytic Bactericidal Performance

Step-scheme (S-scheme) photocatalysts have been proposed for highly efficient charge separation and strong redox activity in the photocatalysis field. Here, we reported a facile strategy to obtain the S-scheme heterojunction composite TiO₂/chlorophyll (Chl). The S-scheme heterojunction enables the significant improvement of electron transfer efficiency at the interfacial heterojunction of TiO₂/Chl. Also, the lifted conduction band and valence band of TiO₂/Chl resulted in more than 1.61 times generation of reactive oxidizing species, compared to that of bare TiO₂. In addition, TiO₂/Chl was applied as a photocatalytic bactericidal material to fabricate commercial masks for prolonged life span of the mask. The TiO₂/Chl-coated mask filter exhibited excellent bactericidal effect on Escherichia coli under light illumination (2.94 × 10⁷ cfu E. coli were killed by 1 cm^-2 coated mask filters within illumination of 3 h), while commercial mask filters showed no bactericidal effect. After three circulation-sterilization tests, the TiO₂/Chl-made mask filter maintained the initial bactericidal effect, which greatly extended the life span of the mask that presents a promising strategy to alleviate the supply stress of masks.