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 BiO 2−x with Bi 3 NbO 7 for photocatalytic inactivation of Microcystic aeruginosa and photodegradation of Microcystin-LR. The oxygen vacancies in BiO 2−x /Bi 3 NbO 7 can effectively promote the chemisorption of O 2 , and the VDW force can drive the photoelectrons in Bi 3 NbO 7 transfer to BiO 2−x through S-scheme transfer path, resulting more electrons reduce O 2 to·O 2 - . Hence, photocatalytic inactivation of algae by BiO 2−x /Bi 3 NbO 7 is 14.17 and 19.05 times higher than BiO 2−x and Bi 3 NbO 7 , respectively. During the photocatalysis, the·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 BiO 2−x /Bi 3 NbO 7 can further availably photodegrade the organic matter, and four possible photodegradation pathways of MC-LR are proposed. • The BiO 2−x and Bi 3 NbO 7 based 2D/2D novel Van der Waals heterostructure is reported. • The oxygen vacancies in BiO 2−x /Bi 3 NbO 7 can promote the chemisorption of O 2 . • BiO 2−x /8.0Bi 3 NbO 7 shows the best photocatalytic inactivation of algae. • Charge separation in VDW heterojunction is enhanced via S-scheme mechanism. • Photocatalytic inactivation mechanism of algae is proposed.