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Title: Electrocatalytic Hydrogen Evolution and Hydrogen Oxidation with a Ni(PS) 2 Complex

Authors:
 [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Department of Chemistry, University of Louisville, 2320 South Brook Street 40292 Louisville KY USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1377932
Grant/Contract Number:
FG02-08CH11538
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
European Journal of Inorganic Chemistry
Additional Journal Information:
Journal Volume: 2017; Journal Issue: 31; Related Information: CHORUS Timestamp: 2017-10-20 17:10:40; Journal ID: ISSN 1434-1948
Publisher:
ChemPubSoc Europe
Country of Publication:
Germany
Language:
English

Citation Formats

Jain, Rahul, Mashuta, Mark S., Buchanan, Robert M., and Grapperhaus, Craig A.. Electrocatalytic Hydrogen Evolution and Hydrogen Oxidation with a Ni(PS)2 Complex. Germany: N. p., 2017. Web. doi:10.1002/ejic.201700590.
Jain, Rahul, Mashuta, Mark S., Buchanan, Robert M., & Grapperhaus, Craig A.. Electrocatalytic Hydrogen Evolution and Hydrogen Oxidation with a Ni(PS)2 Complex. Germany. doi:10.1002/ejic.201700590.
Jain, Rahul, Mashuta, Mark S., Buchanan, Robert M., and Grapperhaus, Craig A.. Fri . "Electrocatalytic Hydrogen Evolution and Hydrogen Oxidation with a Ni(PS)2 Complex". Germany. doi:10.1002/ejic.201700590.
@article{osti_1377932,
title = {Electrocatalytic Hydrogen Evolution and Hydrogen Oxidation with a Ni(PS)2 Complex},
author = {Jain, Rahul and Mashuta, Mark S. and Buchanan, Robert M. and Grapperhaus, Craig A.},
abstractNote = {},
doi = {10.1002/ejic.201700590},
journal = {European Journal of Inorganic Chemistry},
number = 31,
volume = 2017,
place = {Germany},
year = {Fri Jun 30 00:00:00 EDT 2017},
month = {Fri Jun 30 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on August 21, 2018
Publisher's Accepted Manuscript

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

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  • The electrocatalytic reduction of protons to H 2 by [Ni(PPh 2N C6H4-hex 2) 2](BF 4) 2 (where P Ph 2N C6H4-hex 2 = 1,5-di(4-n-hexylphenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) in the highly acidic ionic liquid dibutylformamidium bis(trifluoromethanesulfonyl)amide shows a strong dependence on added water. A turnover frequency of 43,000-53,000 s -1 has been measured for hydrogen production at 25 °C when the mole fraction of water (χ H2O) is 0.72. The same catalyst in acetonitrile with added dimethylformamidium trifluoromethanesulfonate and water has a turnover frequency of 720 s -1. Thus the use of an ionic liquid/aqueous solution enhances the observed catalytic rates by more thanmore » a factor of 50 compared to acids in traditional organic solvents such as acetonitrile. Complexes [Ni(P Ph 2N C6H4X 2) 2](BF 4) 2 (X = H, OMe, CH 2P(O)(OEt) 2, Br) are also catalysts in the ionic liquid/water mixture, and the observed catalytic rates correlate with the hydrophobicity of X. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.« less
  • New [Ni(P R 2N R` 2) 2+(CH 3CN)] 2+ complexes with R = Ph, R` = 4-MeOPh; R = Cy, R` = Ph and a mixed ligand [Ni(P R 2N R` 2)(P R`` 2N R` 2)] 2+ with R = Cy, R` = Ph, R`` = Ph have been synthesized and characterized by single crystal X-ray crystallography. These complexes are shown to be electrocatalysts for the oxidation of formate in solution to produce CO 2, protons, and electrons with rates which are first order in catalyst and in formate at formate concentrations below approximately 0.05 M. For the catalysts studied,more » maximum observed turnover frequencies vary from <1.1 s -1 to 12.5 s -1 at room temperature, which are the highest rates yet reported for formate oxidation by homogeneous catalysts. A mechanistic scheme is proposed which involves an initial nickel complex bound <1-OC(O)H followed by a rate limiting hydride transfer step. An acetate complex demonstrating the η 1-OC(O)CH 3 binding mode to nickel has also been synthesized and characterized by single crystal X-ray crystallography. The pendant amines have been demonstrated to be essential for this electrocatalytic activity as no activity toward formate was found for the similar [Ni(depe) 2][BF 4] 2+ (depe = diethylphosphinoethane) complex. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.« less
  • [Ni(P R 2N R' 2) 2(CH 3CN)] 2+ complexes with R = Ph, R' = 4-MeOPh or R = Cy, R' = Ph , and a mixed-ligand [Ni(P R 2N R' 2)(P R" 2N R' 2)(CH 3CN)] 2+ with R = Cy, R' = Ph, R" = Ph, have been synthesized and characterized by single-crystal X-ray crystallography. These and previously reported complexes are shown to be electrocatalysts for the oxidation of formate in solution to produce CO 2, protons, and electrons, with rates that are first-order in catalyst and formate at formate concentrations below ~0.04 M (34 equiv). At concentrationsmore » above ~0.06 M formate (52 equiv), catalytic rates become nearly independent of formate concentration. For the catalysts studied, maximum observed turnover frequencies vary from <1.1 to 15.8 s –1 at room temperature, which are the highest rates yet reported for formate oxidation by homogeneous catalysts. These catalysts are the only base-metal electrocatalysts as well as the only homogeneous electrocatalysts reported to date for the oxidation of formate. An acetate complex demonstrating an η 1-OC(O)CH 3 binding mode to nickel has also been synthesized and characterized by single-crystal X-ray crystallography. Based on this structure and the electrochemical and spectroscopic data, a mechanistic scheme for electrocatalytic formate oxidation is proposed which involves formate binding followed by a rate-limiting proton and two-electron transfer step accompanied by CO 2 liberation. Finally, the pendant amines have been demonstrated to be essential for electrocatalysis, as no activity toward formate oxidation was observed for the similar [Ni(depe) 2] 2+ (depe = 1,2-bis(diethylphosphino)ethane) complex.« less