Evidence of Enhanced Molecular Oxygen Activity Induced by the Synergistic Effect of Oxygen Vacancies and Ag Nanoparticles in Ag3PO4

This study investigates the synergistic enhancement of molecular oxygen activation (MOA) in silver phosphate (Ag3PO4) photocatalysts modified with oxygen vacancies (OVs) and silver nanoparticles (Ag0). The vacuum-calcined Ag3PO4 exhibited a 2.05-fold increase in the degradation efficiency of cylindrospermopsin (CYN), reaching 88.00% within 5 min, compared to its pristine counterpart. This work proposes a novel dual-modification approach—rarely explored in previous MOA studies—by introducing OVs and Ag0 simultaneously. The characterization results confirmed that OVs improved the charge transfer and adsorption of molecular oxygen, while the Ag0 nanoparticles facilitated electron–hole separation and interfacial charge transfer. Reactive oxygen species (ROS) such as ·O2−, 1O2, H2O2, and ·OH were confirmed via ESR analysis and chemical assays. A detailed mechanism was proposed and illustrated, showing how OVs and Ag0 synergistically promote MOA. These findings highlight a cost-effective method for enhancing photocatalysis and environmental remediation.