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Catalytic hydrogen evolution from a covalently linked dicobaloxime

Valdez, Carolyn N. and Dempsey, Jillian L. and Brunschwig, Bruce S. and Winkler, Jay R. and Gray, Harry B. (2012) Catalytic hydrogen evolution from a covalently linked dicobaloxime. Proceedings of the National Academy of Sciences of the United States of America, 109 (39). pp. 15589-15593. ISSN 0027-8424. PMCID PMC3465440. doi:10.1073/pnas.1118329109.

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A dicobaloxime in which monomeric Co(III) units are linked by an octamethylene bis(glyoxime) catalyzes the reduction of protons from p-toluenesulfonic acid as evidenced by electrocatalytic waves at -0.4 V vs. the saturated calomel electrode (SCE) in acetonitrile solutions. Rates of hydrogen evolution were determined from catalytic current peak heights (k_(app) = 1100 ± 70 M^(-1) s^(-1)). Electrochemical experiments reveal no significant enhancement in the rate of H2 evolution from that of a monomeric analogue: The experimental rate law is first order in catalyst and acid consistent with previous findings for similar mononuclear cobaloximes. Our work suggests that H_2 evolution likely occurs by protonation of reductively generated Co^(II)H rather than homolysis of two Co^(III)H units.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Brunschwig, Bruce S.0000-0002-6135-6727
Winkler, Jay R.0000-0002-4453-9716
Gray, Harry B.0000-0002-7937-7876
Additional Information:© 2012 by the National Academy of Sciences. Edited by Thomas J. Meyer, University of North Carolina at Chapel Hill, Chapel Hill, NC, and approved June 14, 2012 (received for review February 7, 2012). Published online before print July 11, 2012. We thank Ian Stewart, Alex Miller, Bryan Stubbert, Charles McCrory, Xile Hu, and Jonas Peters for insightful discussions. This work was supported by the NSF Center for Chemical Innovation (Powering the Planet, CHE-0802907), the Arnold and Mabel Beckman Foundation, CCSER (Gordon and Betty Moore Foundation), and the BP MC2 program. CNV is grateful for support from the Caltech Summer Undergraduate Research Program and an Amgen Scholars Fellowship. JLD was supported by an NSF Graduate Research Fellowship. Author contributions: C.N.V., J.L.D., J.R.W., and H.B.G. designed research; C.N.V. and J.L.D. performed research; C.N.V. and J.L.D. contributed new reagents/analytic tools; C.N.V., J.L.D., and B.S.B. analyzed data; and C.N.V., J.L.D., J.R.W., and H.B.G. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.
Group:CCI Solar Fuels
Funding AgencyGrant Number
Arnold and Mabel Beckman FoundationUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Subject Keywords:hydrogen evolving catalysts; solar fuel
Issue or Number:39
PubMed Central ID:PMC3465440
Record Number:CaltechAUTHORS:20120904-101007499
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33819
Deposited By: Tony Diaz
Deposited On:04 Sep 2012 17:22
Last Modified:09 Nov 2021 23:04

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