Issue 2, 2015

Tandem redox mediator/Ni(ii) trihalide complex photocycle for hydrogen evolution from HCl


Photoactivation of M–X bonds is a challenge for photochemical HX splitting, particularly with first-row transition metal complexes because of short intrinsic excited state lifetimes. Herein, we report a tandem H2 photocycle based on combination of a non-basic photoredox phosphine mediator and nickel metal catalyst. Synthetic studies and time-resolved photochemical studies have revealed that phosphines serve as photochemical H-atom donors to Ni(II) trihalide complexes to deliver a Ni(I) centre. The H2 evolution catalytic cycle is closed by sequential disproportionation of Ni(I) to afford Ni(0) and Ni(II) and protolytic H2 evolution from the Ni(0) intermediate. The results of these investigations suggest that H2 photogeneration proceeds by two sequential catalytic cycles: a photoredox cycle catalyzed by phosphines and an H2-evolution cycle catalyzed by Ni complexes to circumvent challenges of photochemistry with first-row transition metal complexes.

Graphical abstract: Tandem redox mediator/Ni(ii) trihalide complex photocycle for hydrogen evolution from HCl

Supplementary files

Article information

Article type
Edge Article
04 Aug 2014
07 Oct 2014
First published
08 Oct 2014
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2015,6, 917-922

Author version available

Tandem redox mediator/Ni(II) trihalide complex photocycle for hydrogen evolution from HCl

S. J. Hwang, D. C. Powers, A. G. Maher and D. G. Nocera, Chem. Sci., 2015, 6, 917 DOI: 10.1039/C4SC02357A

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