Porphyrin-decorated perylene-nickel-MOF nanocomposite: photoinduced electron and energy transfer for photoelectrochemical applications.

Abstract

Developing aqueous supramolecular light-harvesting systems that combine broad solar spectrum absorption with efficient photoinduced electron and energy transfer remains a significant challenge for sustainable energy production. To address this goal, a novel supramolecular light-harvesting system was constructed in an aqueous medium via electrostatic interactions between porphyrin-5,10,15,20-tetrakis(1-methylpyridin-1-ium) 4-methylbenzenesulfonate (TMPyP) and perylene-based nickel MOF nanosheets (TMPyP/Ni-PTCA-SDS). The structure and morphology of the system were investigated using various spectroscopic techniques. Steady-state absorption measurements demonstrated that the TMPyP/Ni-PTCA-SDS nanosheets possess high light-harvesting efficiency across a broad range of the solar spectrum, indicating their suitability for light energy conversion. Upon photoexcitation of the TMPyP entity, steady-state and time-resolved fluorescence measurements revealed intra-supramolecular electron transfer from the electron-donating TMPyP to the electron-accepting Ni-PTCA-SDS nanosheets, proceeding with an efficiency of 98% and a rapid rate constant of 1.25 × 1010 s-1. Conversely, photoexcitation of the Ni-PTCA-SDS component drove Förster resonance energy transfer (FRET) from the singlet state of Ni-PTCA-SDS to TMPyP with an efficiency of 69%. Furthermore, complementary cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and chronoamperometry confirm enhanced interfacial electron transfer and reduced charge-transfer resistance under illumination. These findings provide an effective strategy for constructing stable, aqueous supramolecular platforms featuring efficient photoinduced electron- and energy-transfer relays for light-harvesting and solar energy conversion applications.

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