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.

Atomic dispersed Fe-based catalysts (Fe-N-C) are a promising class of non-noble metal oxygen reduction reaction (ORR) materials. However, their practical application is severely limited by slow mass transfer and insufficient oxygen supply at device level, like the fuel cells. Herein, we report a rational design of a unique yolk-shell nanostructured catalyst (Fe-N-C_T) with triple-layer actives site distribution, exhibiting competitive ORR performance. Comprehensive characterization confirms its unique yolk-shell nanostructure, showing that the Fe-Nx moieties are atomically dispersed in the core, inner shell, and outer surface, significantly improving the active site density. Fe-N-C_T exhibits excellent ORR activity and stability in acidic media. Integration into an H₂-air fuel cell achieves a peak power density of 496 mW·cm⁻² and maintained stable operation with minimal voltage drop during 30,000 accelerated durability cycles. In-situ Raman spectroscopy and COMSOL simulations show that the unique yolk-shell structure acts as an oxygen reservoir, enriching O₂ molecules and reducing mass transfer polarization, thereby achieving excellent ORR performance at the device level.