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Title: Electrocatalytic Hydrogen Evolution under Acidic Aqueous Conditions and Mechanistic Studies of a Highly Stable Molecular Catalyst

Electrocatalytic activity of a water-soluble nickel complex, [Ni(DHMPE) 2] 2+ (DHMPE = 2-bis(di(hydroxymethyl)phosphino)ethane), for the hydrogen evolution reaction (HER) at pH 1 is reported. The catalyst functions at a rate of ~10 3 s -1 (k obs) with high Faradaic efficiency. Quantification of the complex before and after 18+ hours of electrolysis reveals negligible decomposition under catalytic conditions. Although highly acidic conditions are common in electrolytic cells, this is a rare example of a homogeneous catalyst for HER that functions with high stability at low pH. The stability of the compound and proposed catalytic intermediates enabled detailed mechanistic studies. The thermodynamic parameters governing electron and proton transfer were used to determine the appropriate reductants and acids to access the catalytic cycle in a stepwise fashion, permitting direct spectroscopic identification of intermediates. Finally, these studies support a mechanism for proton reduction that proceeds through two-electron reduction of the nickel(II) complex, protonation to generate [HNi(DHMPE) 2] +, and further protonation to initiate hydrogen bond formation.
Authors:
 [1] ;  [1]
  1. Univ. of California, Irvine, CA (United States). Dept. of Chemistry
Publication Date:
Grant/Contract Number:
SC0012150
Type:
Published Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 138; Journal Issue: 43; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Research Org:
Univ. of California, Irvine, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1415252
Alternate Identifier(s):
OSTI ID: 1474066

Tsay, Charlene, and Yang, Jenny Y. Electrocatalytic Hydrogen Evolution under Acidic Aqueous Conditions and Mechanistic Studies of a Highly Stable Molecular Catalyst. United States: N. p., Web. doi:10.1021/jacs.6b05851.
Tsay, Charlene, & Yang, Jenny Y. Electrocatalytic Hydrogen Evolution under Acidic Aqueous Conditions and Mechanistic Studies of a Highly Stable Molecular Catalyst. United States. doi:10.1021/jacs.6b05851.
Tsay, Charlene, and Yang, Jenny Y. 2016. "Electrocatalytic Hydrogen Evolution under Acidic Aqueous Conditions and Mechanistic Studies of a Highly Stable Molecular Catalyst". United States. doi:10.1021/jacs.6b05851.
@article{osti_1415252,
title = {Electrocatalytic Hydrogen Evolution under Acidic Aqueous Conditions and Mechanistic Studies of a Highly Stable Molecular Catalyst},
author = {Tsay, Charlene and Yang, Jenny Y.},
abstractNote = {Electrocatalytic activity of a water-soluble nickel complex, [Ni(DHMPE)2]2+ (DHMPE = 2-bis(di(hydroxymethyl)phosphino)ethane), for the hydrogen evolution reaction (HER) at pH 1 is reported. The catalyst functions at a rate of ~103 s-1 (kobs) with high Faradaic efficiency. Quantification of the complex before and after 18+ hours of electrolysis reveals negligible decomposition under catalytic conditions. Although highly acidic conditions are common in electrolytic cells, this is a rare example of a homogeneous catalyst for HER that functions with high stability at low pH. The stability of the compound and proposed catalytic intermediates enabled detailed mechanistic studies. The thermodynamic parameters governing electron and proton transfer were used to determine the appropriate reductants and acids to access the catalytic cycle in a stepwise fashion, permitting direct spectroscopic identification of intermediates. Finally, these studies support a mechanism for proton reduction that proceeds through two-electron reduction of the nickel(II) complex, protonation to generate [HNi(DHMPE)2]+, and further protonation to initiate hydrogen bond formation.},
doi = {10.1021/jacs.6b05851},
journal = {Journal of the American Chemical Society},
number = 43,
volume = 138,
place = {United States},
year = {2016},
month = {7}
}