Boosting photo-Fenton process enabled by ligand-to-cluster charge transfer excitations in iron-based metal organic framework

Abstract

Iron-based metal organic frameworks (MOFs) are widely adopted to mediate heterogeneous photo-Fenton reaction, but poor charge separation efficiency in iron-oxo clusters of MOF usually results in the dull Fe(III)/Fe(II) transformation. In this study, ligand-to-cluster charge transfer (LCCT) excitations were first introduced to photo-Fenton process toward accelerating Fe(III)/Fe(II) transformation by constructing new iron-based MOF nanorods with porphyrin ligand (Fe-TCPP). Fe-TCPP with LCCT excitations showed a maximum kinetic constant of 0.23 min-1 for ciprofloxacin (CIP) degradation at neutral pH under visible light irradiation, which is remarkably better than most of the state-of-the-art photocatalysts. Experimental and theoretical analyses collaboratively verify that LCCT excitations within Fe-TCPP dramatically accelerate Fe(III)/Fe(II) transformation, which generate more ∙OH for quick CIP elimination. Additionally, this LCCT excitations strategy is also effective for the photo-Fenton-like system induced by copper-based MOFs. Our study presents a novel strategy to intensify MOFs based photo-Fenton/Fenton-like processes, upon which the high-efficiency contaminant removal is expected.