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[Display omitted] • Electron localization is the primary reason for the ineffective charge separation process at the porphyrin-based MOF ligands. • Introducing Cu species into the conjugated framework allows efficient electron transitions by delocalizing the π-electrons. • Cu-induced electron delocalization significantly enhances the removal rate of ciprofloxacin. • The delocalized π-electrons are transferred to the Cu site for efficient activation of PDS to generate OH and SO 4 − . Photocatalytic persulfate activation provides a promising approach for the elimination of persistent organic pollutants from water. This has been exemplified in porphyrin-based metal organic frameworks (PMOFs), which however come with ineffective electron transition within the porphyrin ligand. Herein, we present a Cu ion modification strategy capable of boosting electron transition by inducing electron delocalization under visible light. The introduction of Cu ions increased the degradation rate constant of ciprofloxacin (CIP) by nearly 44 times, surpassing most state-of-the-art photocatalysts. The in-situ characterizations and theoretical calculations suggest that π-electron localization constitutes the origin of ineffective electron transition in PMOFs. The introduction of Cu ions induces π-electron delocalization to intensify the π → π* transition, forming electron-rich centers of Cu to lower the energy barrier for O-O bond cleavage. This work offers fundamental insights into the electron transition within PMOFs, upon which the universal strategy is proposed for improved water decontamination performance via persulfate activation. [ABSTRACT FROM AUTHOR]

This work demonstrates that the photoreduction of hexavalent chromium using iron-based metal organic framework was able to be enhanced through doping molybdenum disulfide. The 1.5 wt % molybdenum disulfide doped iron-based metal organic framework exhibited the best photocatalytic activity towards hexavalent chromium reduction with an efficiency of 98.8% over 60 min, accompanied by remarkable repeatability and stability. The enhancement of photocatalytic efficiency could be achieved by (i) relieving the recombination process of photogenerated carriers in iron-based metal organic framework resulting from the formation of heterojunction, (ii) reducing photogenerated electrons transfer resistance from the interior to the surface of iron-based metal organic framework because of favorable electron transfer of molybdenum disulfide, and (iii) regulating the positive charge distribution on the surface of iron-based metal organic framework. Importantly, nanosecond time-resolved transient absorption spectroscopy further disclosed that the doping of molybdenum disulfide fundamentally improved the utilization of photogenerated electrons. This work evidences the important role of heterojunction from a microscopic perspective, which provides inspiration for the preparation of highly-efficient environmental functional photocatalysts based on iron-based metal organic frameworks. [Display omitted] • Elegant visible-light-driven MoS 2 @Fe-MOF photocatalysts were fabricated. • Unique adsorption capacity of Cr(VI) was given as a prerequisite for photoreduction. • Accelerated Cr(VI) reduction was due to heterojunction and improved conductivity. • Nanosecond transient absorption spectroscopy proved heterojunction existence. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • LCCT excitations were first introduced to MOFs based photo-Fenton process. • Fe-TCPP with LCCT excitations displayed best antibiotic degradation performance. • LCCT excitations occurrence within Fe-TCPP was identified by different methods. • LCCT excitations within Fe-TCPP speed Fe(III)/Fe(II) transformation and ∙OH generation. [ABSTRACT FROM AUTHOR]