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Trapping an Iron(VI) Water-Splitting Intermediate in Nonaqueous Media

Hunter, Bryan M. and Thompson, Niklas B. and Müller, Astrid M. and Rossman, George R. and Hill, Michael G. and Winkler, Jay R. and Gray, Harry B. (2018) Trapping an Iron(VI) Water-Splitting Intermediate in Nonaqueous Media. Joule, 2 (4). pp. 747-763. ISSN 2542-4351. http://resolver.caltech.edu/CaltechAUTHORS:20180207-065509383

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Abstract

We report in situ spectroscopic measurements in nonaqueous media designed to trap an exceptionally strong oxidant generated electrochemically from an iron-containing nickel layered double hydroxide ([NiFe]-LDH) material. Anodic polarization of this material in acetonitrile produces metal-oxo vibrational spectroscopic signatures along with an extremely narrow near-infrared luminescence peak that strongly indicate that the reactive intermediate is cis-dioxo-iron(VI). Chemical trapping experiments reveal that addition of H_2O to the polarized electrochemical cell produces hydrogen peroxide; and, most importantly, addition of HO– generates oxygen. Repolarization of the electrode restores the iron(VI) spectroscopic features, confirming that the high-valent oxo complex is active in the electrocatalytic water oxidation cycle.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.joule.2018.01.008DOIArticle
https://www.sciencedirect.com/science/article/pii/S2542435118300369PublisherArticle
ORCID:
AuthorORCID
Thompson, Niklas B.0000-0003-2745-4945
Rossman, George R.0000-0002-4571-6884
Winkler, Jay R.0000-0002-4453-9716
Additional Information:© 2018 Elsevier Inc. Received: December 20, 2017. Revised: January 8, 2018. Accepted: January 11, 2018. Published: February 6, 2018. This work was supported by the NSF CCI Solar Fuels Program ( CHE- 1305124 ) and the Arnold and Mabel Beckman Foundation, with additional support from NSF EAR-1322082 . B.M.H. is a Fellow of the Resnick Sustainability Institute at Caltech. The authors thank Jonas Peters for helpful discussions. Additional data and methods are available in the Supplemental Information. Author Contributions: B.M.H. designed and performed the experiments; N.B.T. collected and analyzed the Mössbauer spectra; A.M.M. synthesized and characterized the materials; G.R.R. assisted with luminescence and Raman electrochemistry; M.G.H. assisted with electrochemistry and IR spectroelectrochemistry; J.R.W. and H.B.G., with the other authors, developed the proposed mechanism. All authors wrote the manuscript. The authors declare no competing interests.
Group:CCI Solar Fuels, Resnick Sustainability Institute
Funders:
Funding AgencyGrant Number
NSFCHE- 1305124
Arnold and Mabel Beckman FoundationUNSPECIFIED
NSFEAR-1322082
Resnick Sustainability InstituteUNSPECIFIED
Subject Keywords:electrocatalysis; water splitting; water oxidation; solar fuels; spectroscopy; layered double hydroxides; in situ electrochemistry; spectroelectrochemistry; catalysis
Record Number:CaltechAUTHORS:20180207-065509383
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20180207-065509383
Official Citation:Bryan M. Hunter, Niklas B. Thompson, Astrid M. Müller, George R. Rossman, Michael G. Hill, Jay R. Winkler, Harry B. Gray, Trapping an Iron(VI) Water-Splitting Intermediate in Nonaqueous Media, Joule, Volume 2, Issue 4, 2018, Pages 747-763, ISSN 2542-4351, https://doi.org/10.1016/j.joule.2018.01.008. (http://www.sciencedirect.com/science/article/pii/S2542435118300369)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84697
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:07 Feb 2018 15:49
Last Modified:25 Apr 2018 17:12

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