A Novel Mononuclear Nickel Complex as a Precatalyst for Ionomer-Dependent Oxygen Evolution Reaction Activity
- 1Department of Chemistry and Industrial Chemistry
- 2University of Genoa
- 3National Interuniversity Consortium of Materials Science and Technology–INSTM
Abstract
In electrocatalytic water splitting, ionomer-catalyst interactions can significantly influence electrochemical performance. Molecular metal–organic complexes offer a tractable platform to investigate such interactions. Here we report a novel nickel–2methylimidazole complex, [Ni(2-MeIm)4(NO3)]NO3, with Ni@N4O2 coordination environment. The structure of this new material is established by single-crystal X-ray diffraction and supported by vibrational spectroscopy and thermal analysis. We evaluate the complex as an oxygen evolution reaction precatalyst in 1.0mol L−1 KOH and show that its apparent activity depends strongly on the ionomer used in the catalyst ink. With Aemion+, an anion-exchange ionomer the catalyst reaches 10mAcm−2 current density at an overpotential of 0.331V, whereas the same catalyst formulated with Nafion exhibits a markedly reduced activity with an overpotential of 0.403V. The impedance spectra recorded at 1.6V vs RHE show considerable differences in charge-transfer resistances between the two formulations, consistent with differences in interfacial charge-transfer kinetics. We propose that specific catalyst–ionomer interactions may modulate active-site accessibility and the in situ transformation of the molecular precursor into catalytically competent NiOOH.
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BibTeX
@misc{varghese2026novel,
title = {{A Novel Mononuclear Nickel Complex as a Precatalyst for Ionomer-Dependent Oxygen Evolution Reaction Activity}},
author = {Neethu Kochukunnel Varghese and Serena De Negri and Pavlo Solokha and Antonio Comite},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009627/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009627/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - A Novel Mononuclear Nickel Complex as a Precatalyst for Ionomer-Dependent Oxygen Evolution Reaction Activity
AU - Neethu Kochukunnel Varghese
AU - Serena De Negri
AU - Pavlo Solokha
AU - Antonio Comite
PY - 2026
DA - 2026/09/29
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009627/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009627/v1
AB - In electrocatalytic water splitting, ionomer-catalyst interactions can significantly influence electrochemical performance. Molecular metal–organic complexes offer a tractable platform to investigate such interactions. Here we report a novel nickel–2methylimidazole complex, [Ni(2-MeIm)4(NO3)]NO3, with Ni@N4O2 coordination environment. The structure of this new material is established by single-crystal X-ray diffraction and supported by vibrational spectroscopy and thermal analysis. We evaluate the complex as an oxygen evolution reaction precatalyst in 1.0mol L−1 KOH and show that its apparent activity depends strongly on the ionomer used in the catalyst ink. With Aemion+, an anion-exchange ionomer the catalyst reaches 10mAcm−2 current density at an overpotential of 0.331V, whereas the same catalyst formulated with Nafion exhibits a markedly reduced activity with an overpotential of 0.403V. The impedance spectra recorded at 1.6V vs RHE show considerable differences in charge-transfer resistances between the two formulations, consistent with differences in interfacial charge-transfer kinetics. We propose that specific catalyst–ionomer interactions may modulate active-site accessibility and the in situ transformation of the molecular precursor into catalytically competent NiOOH.
ER -