Nanoconfinement Engineering of MOF-Derived-Hollow-Heterojunctions Towards Enhanced Photocatalysis

Rational heterostructure design, tailored architectures, and enhanced charge dynamics are key factors for developing efficient photocatalysis for environmental remediation. In this study, we employed a metal–organic framework (MOF)-derived strategy to construct hollow polyhedral bimetallic sulfide heterojunctions (Co 9 S 8 /Ag 2 S) via nanoconfinement engineering. ZIF-67 is transformed into an amorphous cobalt sulfide scaffold, followed by in-situ growth of Ag 2 S nanoparticles and subsequent annealing. This process yields a well-defined heterostructure with intimate interfacial contact, facilitating efficient charge separation and transfer. Under UV light irradiation, the Co 9 S 8 /Ag 2 S heterojunction achieves a photocatalytic tetracycline degradation efficiency of 99.3%, significantly outperforming most other different photocatalyst systems. Comprehensive mechanistic studies reveal that a built-in electric field and nanoconfinement effects synergistically modulate the charge transfer dynamics. Density functional theoretical (DFT) computation results have also shown that the electrons were tended to flow from Co 9 S 8 to Ag 2 S until a new equilibrium was established over the interface. The intensity of overlap between Co, Ag and S elements across the Fermi level (E f ) was enhanced compared with that in Co 9 S 8 or Ag 2 S, which means that the heterojunction formation facilitated charge transfer between Co 9 S 8 and Ag 2 S. Overall, this work advances photocatalyst design and illustrates the potential of MOF-derived heterostructures for efficient, sustainable water treatment applications. A hollow Co 9 S 8 /Ag 2 S heterojunction is engineered with a built-in electric field confirmed by DFT and nanoconfinement. This study demonstrates a rational material design strategy that integrates MOF-self-templating, hollow architecture engineering, and interfacial heterojunction construction to synergistically enhance photocatalytic performance. • A unique MOF-self-templating strategy coupled with nanoconfinement prolongs carrier lifetimes and enhances charge separation and transfer. • Achieves 99.3% tetracycline degradation under UV light, surpassing most reported photocatalysts. • The hollow polyhedral architectural advantage provides multiple light reflections for designing high-performance photocatalysts. • DFT calculations confirm electron transfer pathway from Co 9 S 8 to Ag 2 S and improved heterojunction interfacial electronic overlap.