Photochemical Hydrogen Evolution from Neutral Water with a Cobalt Metallopeptide Catalyst

Abstract

CoGGH, a Gly-Gly-His tripeptide coordinated to a cobalt ion, is shown to catalyze the reduction of aqueous protons to hydrogen (H 2 ) in a light-driven reaction in water near neutral pH. Using [Ru(bpy) 3 ] 2+ as a photosensitizer and ascorbate as an electron donor, a turnover number up to 2200 with respect to CoGGH has been observed with the system remaining active for more than 48 h. The reaction conditions that favor H 2 production are consistent with a reductive quenching mechanism. Results also suggest that CoGGH is robust under these reaction conditions and loss of activity over time results from [Ru(bpy) 3 ] 2+ degradation.

Theoretical Study of the Full Photosolvolysis Mechanism of [Ru(bpy)3]2+: Providing a General Mechanistic Roadmap for the Photochemistry of [Ru(N^N)3]2+-Type Complexes toward Both Cis and Trans Photoproducts

“…32 What makes these compounds especially powerful is the tremendous tuning of their properties resulting from chemists' endless creativity. 33,34,35,36,37 Because photoinstability issues are deleterious to photophysical applications, 38,39 the same period has also witnessed thorough photoreactivity studies with a variety of starting compounds and incoming ligands (e.g. anions, coordinating solvents).…”

Enhanced Hydrogen Evolution in Neutral Water Catalyzed by a Cobalt Complex with a Softer Polypyridyl Ligand

“…A lower loading of 3 b yields higher activities, with a TON of 15 000 at 0.5 μ m (Figure S9 b). Photocatalytic HERs in neutral aqueous solutions have been reported for [Co(PY4MeH 2 )(CH 3 CN)(CF 3 SO 3 )](CF 3 SO 3 ), a cobalt metallopeptide, and two cobalt porphyrins with TONs of 2400, 2200, 725, and 6400, respectively . Therefore, 3 b is among the most active molecular Co catalysts reported for photolytic HER in neutral aqueous solutions …”

Light‐driven catalysis with engineered enzymes and biomimetic systems

“…11). CoGGH was previously reported to be active for electrochemical proton reduction [174], and subsequently was incorporated into a photochemical system by pairing with [Ru(bpy) 3 ] 2+ and ascorbic acid in water near neutral pH [175]. Although it is not a full protein scaffold, the metal derivatives of the GGH peptide are water soluble.…”