Photocatalytic O2 activation enhancement and algae inactivation mechanism of BiO2-x/Bi3NbO7 van der Waals heterojunction

The removal of algae by reactive oxygen species (ROS) through photocatalytic O-2 activation is still a challenge. Herein, we constructed a van der Waals (VDW) heterojunction photocatalyst by coupling BiO2-x with Bi3NbO7 for photocatalytic inactivation of Microcystic aeruginosa and photodegradation of Microcystin-LR. The oxygen vacancies in BiO2-x/Bi3NbO7 can effectively promote the chemisorption of O-2, and the VDW force can drive the photoelectrons in Bi3NbO7 transfer to BiO2-x through S-scheme transfer path, resulting more electrons reduce O-2 to center dot O-2(-). Hence, photocatalytic inactivation of algae by BiO2-x/Bi3NbO7 is 14.17 and 19.05 times higher than BiO(2-x)and Bi3NbO7, respectively. During the photocatalysis, the center dot O-2(-) damages the antioxidant system and cell membrane of algae, resulting in the release of organic matter and Microcystin-LR and finally causing the death of algae. The three-dimensional fluorescence spectroscopy indicates BiO2-x/Bi3NbO7 can further availably photo-degrade the organic matter, and four possible photodegradation pathways of MC-LR are proposed.

Automated summary

In this study, a BiO2-x/Bi3NbO7 heterojunction photocatalyst was constructed to achieve efficient inactivation of algae and degradation of organic matter through the interaction of oxygen vacancies and VDW force. The research results are of great significance for the treatment of algae pollution.