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Enhanced Hydrogen Evolution in Neutral Water Catalyzed by a Cobalt Complex with a Softer Polypyridyl Ligand
Abstract To explore the structure–function relationships of cobalt complexes in the catalytic hydrogen evolution reaction (HER), we studied the substitution of a tertiary amine with a softer pyridine group and the inclusion of a conjugated bpy unit in a Co complex with a new pentadentate ligand, 6‐[6‐(1,1‐di‐pyridin‐2‐yl‐ethyl)‐pyridin‐2‐ylmethyl]‐[2,2′]bipyridinyl (Py3Me‐Bpy). These modifications resulted in significantly improved stability and activity in both electro‐ and photocatalytic HER in neutral water. [Co(Py3Me‐Bpy)(OH2)](PF6)2catalyzes the electrolytic HER at −1.3 V (vs. SHE) for 20 hours with a turnover number (TON) of 266 300, and photolytic HER for two days with a TON of 15 000 in pH 7 aqueous solutions. The softer ligand scaffold possibly provides increased stability towards the intermediate CoIspecies. DFT calculations demonstrate that HER occurs through a general electron transfer/proton transfer/electron transfer/proton transfer pathway, with H2released from the protonation of CoII−H species.
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- Award ID(s):
- 1800201
- PAR ID:
- 10154881
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 59
- Issue:
- 31
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 12694-12697
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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