Oxygen vacancy self-healing in Bi 2 O 3 /Bi 2 O 2 Co 3 heterojunctions under visible light: enhanced sulfadiazine photocatalytic degradation

Lattice defect engineering is vital for semiconductor photocatalysts, where oxygen vacancies (OVs) narrow the band gap, boost visible-light utilization and create active sites. Efficient OVs introduction and structural optimization are key to enhancing catalytic performance. Previously, OVs were incorporated into Bi2O2CO3 (BOC) via UV-mediated Ni ion doping to endow visible-light responsiveness. Herein, a Z-scheme Bi2O3/Bi2O2CO3-OVs heterojunction was fabricated by calcination and UV treatment. It combines the merits of Z-scheme heterojunctions for efficient photocarrier separation and OVs for rich active sites. Under visible light, it degrades over 99% sulfadiazine within 60 min with TOC removal above 80%. Its OVs show light-induced self-healing, retaining 93% activity after 10 cycles. First-principles calculations validated the Z-scheme formation mechanism. This work offers a feasible route to self-healing OV-rich heterojunctions and guides efficient removal of sulfadiazine in water.