Hetero-motif PMo@VioPAFs for highly efficient photocatalytic degradation of antibiotics: Performance and synergistic mechanism

To mitigate the significant ecological and health threats posed by the pervasive discharge of emerging organic pollutants like antibiotics, developing robust, visible-light-responsive photocatalysts with high catalytic activity has emerged as a pivotal strategy for efficient wastewater remediation. Herein, a series of polyoxomolybdate-based viologen porous aromatic frameworks (PMo@VioPAFs) composites featuring hetero-motif structures were successfully synthesized via a mild self-assembly strategy. Driven by the strong electrostatic coupling between cationic VioPAF and anionic Keggin-type PMo clusters, the composite retains its structural integrity and delivers outstanding cycling stability. A key structural feature is the self-reduction property of viologen units, which induces the formation of low-valent molybdenum species, thereby multiplying available catalytic active sites. Furthermore, the hetero-motif heterostructure facilitates efficient separation and directional migration of photo-generated carriers. The optimized PMo@VioPAFs(2:1) exhibited superior photocatalytic performance, achieving >98% conversion of tetracycline within 50 min and total organic carbon removal efficiency reached nearly 80% within 90 min, significantly outperforming traditional POM-based systems. Mechanistic studies reveal a synergistic dual-site, dual-track reaction pathway, where direct hole-mediated oxidation and indirect radical-triggered (·O₂⁻ and ·OH) degradation coexist. This work provides a robust design template for high-efficiency, visible-light-active photocatalysts in recalcitrant wastewater treatment.