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A Bioinspired System for Light‐Driven Water Oxidation with a Porphyrin Sensitizer and a Tetrametallic Molecular Catalyst
Author(s) -
Natali Mirco,
Deponti Elisa,
Vilona Debora,
Sartorel Andrea,
Bonchio Marcella,
Scandola Franco
Publication year - 2015
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201500063
Subject(s) - chemistry , photochemistry , persulfate , artificial photosynthesis , quantum yield , catalysis , water splitting , quenching (fluorescence) , photosensitizer , porphyrin , electron transfer , photocatalysis , electron acceptor , singlet oxygen , oxygen evolution , rose bengal , sodium persulfate , oxygen , electrochemistry , fluorescence , organic chemistry , physics , electrode , quantum mechanics
Inspired by natural photosynthesis, the aim of light‐driven water splitting is to produce renewable fuels by exploiting solar radiation. Sustained hydrogen production is desirable in such systems, and the oxidation of water to oxygen is currently recognized as the bottleneck of the entire process. Therefore, solutions for this difficult task retain a fundamental interest. In this paper, we present a bioinspired, three‐component system for water oxidation that comprises a tetracationic porphyrin Zn II complex as the photosensitizer, a tetraruthenium water‐oxidation catalyst, and sodium persulfate as the electron acceptor. An in‐depth photophysical study reveals the photogeneration of a pentacation radical of the porphyrin (quantum yield up to Φ = 1.01) upon oxidative quenching of the triplet excited state by persulfate. Electron transfer from the water‐oxidation catalyst to the pentacation radical (hole scavenging) is slow (bimolecular rate constant, k < 4 × 10 7 M –1 s –1 ), and this is likely the main reason for the low efficiency of the system in photocatalytic tests for water oxidation. Perspectives for improvements of the system and for the development of a light‐activated device for water splitting are discussed.