An Intramolecular Cobalt–Peptoid Complex as an Effective Catalyst for Light-Driven Water Oxidation at pH 7

TL;DR

Scientists created a cobalt-based catalyst that efficiently splits water under neutral pH using light, offering a potential solution for clean energy production.

Contribution

A bioinspired intramolecular Co(III)–peptoid complex is introduced as an efficient catalyst for light-driven water oxidation at pH 7.

Findings

The CoTBE complex achieves a maximal turnover number of about 51 in 45 minutes under blue LED light.

The peptoid ligand includes a proton shuttling ethanol group, enabling activity at neutral pH.

The catalyst operates efficiently in phosphate buffer with a photosensitizer and sacrificial electron acceptor.

Abstract

Light-driven water
splitting to produce hydrogen as an alternative
clean renewable fuel for coping with the future energy crisis is one
of the most important challenges of the 21st century. Water oxidation
(WO), which is the first step in the water splitting process, is catalyzed
in nature by a Mn4CaO5 cluster near pH 6. However,
developing a synthetic catalyst for WO, which is based on nonprecious
metal ions and can operate near neutral pH (e.g., pH 7.0), is still
challenging. Herein, we demonstrate that the bioinspired intramolecular
Co­(III)–peptoid complex CoTBE is a stable and
efficient molecular catalyst for light-driven WO in phosphate buffer
at pH 7 in the presence of a photosensitizer and a sacrificial electron
acceptor under irradiation of blue LED light with an intensity of
1.5 mW/cm2, with a maximal turnover number of about 51
in 45 min. Co­(III) is coordinated and stabilized by terpyridine and
bipyridine groups incorporated within the peptoid ligand, which also
includes an ethanol group that acts as a proton shuttler and thus
facilitates the activity at pH 7.

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