TY - JOUR
T1 - Characterization of paramagnetic states in an organometallic nickel hydrogen evolution electrocatalyst
AU - Chakrabarti, Sagnik
AU - Sinha, Soumalya
AU - Tran, Giang N.
AU - Na, Hanah
AU - Mirica, Liviu M.
N1 - Funding Information:
We thank the National Science Foundation (CHE-1925751 and CHE-2155160 to L.M.M.) for financial support, and the Department of Energy BES Catalysis Science Program (DE-SC0006862 to L.M.M.) for support of the initial ligand synthesis work. We thank Prof. Nigam P. Rath (Univ. of Missouri—St. Louis) for obtaining the crystal structures of NCHS2 and 2 . We thank Dr. Toby Woods (University of Illinois at Urbana-Champaign) for his help with the solution of crystal structure data for [2-Br] . We also thank Dr. Leonel Griego and Yusuff Moshood for helpful discussions regarding EPR simulations. We thank Qi Hua (Gewirth group) for her assistance in collecting the SEM/EDX data. We thank the operators of the research facilities at the University of Illinois at Urbana-Champaign for their help. +
Publisher Copyright:
© 2023, The Author(s).
PY - 2023/12
Y1 - 2023/12
N2 - Significant progress has been made in the bioinorganic modeling of the paramagnetic states believed to be involved in the hydrogen redox chemistry catalyzed by [NiFe] hydrogenase. However, the characterization and isolation of intermediates involved in mononuclear Ni electrocatalysts which are reported to operate through a NiI/III cycle have largely remained elusive. Herein, we report a NiII complex (NCHS2)Ni(OTf)2, where NCHS2 is 3,7-dithia-1(2,6)-pyridina-5(1,3)-benzenacyclooctaphane, that is an efficient electrocatalyst for the hydrogen evolution reaction (HER) with turnover frequencies of ~3,000 s−1 and a overpotential of 670 mV in the presence of trifluoroacetic acid. This electrocatalyst follows a hitherto unobserved HER mechanism involving C-H activation, which manifests as an inverse kinetic isotope effect for the overall hydrogen evolution reaction, and NiI/NiIII intermediates, which have been characterized by EPR spectroscopy. We further validate the possibility of the involvement of NiIII intermediates by the independent synthesis and characterization of organometallic NiIII complexes.
AB - Significant progress has been made in the bioinorganic modeling of the paramagnetic states believed to be involved in the hydrogen redox chemistry catalyzed by [NiFe] hydrogenase. However, the characterization and isolation of intermediates involved in mononuclear Ni electrocatalysts which are reported to operate through a NiI/III cycle have largely remained elusive. Herein, we report a NiII complex (NCHS2)Ni(OTf)2, where NCHS2 is 3,7-dithia-1(2,6)-pyridina-5(1,3)-benzenacyclooctaphane, that is an efficient electrocatalyst for the hydrogen evolution reaction (HER) with turnover frequencies of ~3,000 s−1 and a overpotential of 670 mV in the presence of trifluoroacetic acid. This electrocatalyst follows a hitherto unobserved HER mechanism involving C-H activation, which manifests as an inverse kinetic isotope effect for the overall hydrogen evolution reaction, and NiI/NiIII intermediates, which have been characterized by EPR spectroscopy. We further validate the possibility of the involvement of NiIII intermediates by the independent synthesis and characterization of organometallic NiIII complexes.
UR - http://www.scopus.com/inward/record.url?scp=85148357676&partnerID=8YFLogxK
U2 - 10.1038/s41467-023-36609-7
DO - 10.1038/s41467-023-36609-7
M3 - Article
C2 - 36807358
AN - SCOPUS:85148357676
SN - 2041-1723
VL - 14
JO - Nature communications
JF - Nature communications
IS - 1
M1 - 905
ER -