Cobalt-induced localized electronic reconstruction and global band structure adjustment enhance photo-Fenton-like activity in iron-based metal–organic frameworks

Abstract

Modulations in interatomic localized electron density and occupation states are vital for facilitating efficient Photo-Fenton-like reactions in iron-based metal–organic frameworks (Fe-MOFs). Here, Co-doped Fe-MOFs (FeCox-MOFs) were synthesized through a one-step hydrothermal method, introducing Co(II) with a distinct Jahn-Teller effect and electronegativity. This led to local ligand deficiency, forming exposed Fe-O-Co clusters. This integration facilitated Co coordinatively unsaturated sites (CUSs) to partially acquire electrons from adjacent Fe CUSs, further optimizing the d-band center. As a result, the d-band centers of both Fe (-1.32 eV) and Co (-1.52 eV) CUSs in FeCo2/1-MOFs were higher than that of Fe sites (-1.87 eV) in Fe-MOFs, resulting in enhanced adsorption capability of persulfate (PMS). Notably, Co(II) underwent ligand-driven electron redistribution, populating antibonding orbitals (eg*) and increasing their energy, thereby elevating the conduction band. Concurrently, Co 3d orbitals served as donor energy levels, narrowing the band gap. With the tuned band structure, the eg* of Fe(III) sites experienced rapid electron population upon photoexcitation, expediting Co(III) reduction and enhancing PMS activation. This study provides a unique perspective on the catalytic application of FeCox-MOFs in photo-Fenton-like reactions.