Engineering Fe-based OER electrocatalyst stability through alloy-driven modulation of Fe-O bond covalency and hydroxyl coverage
4 affiliations
- 1Dept. of Biomedical and Chemical Engineering
- 2Syracuse University
- 3Center for Functional Nanomaterials
- 4Brookhaven National Laboratory
Abstract
Fe-based oxyhydroxides are earth-abundant alternatives to costly Ir and Ru catalyst for the oxygen evolution reaction (OER), but their stability in alkaline electrolyte limits their applicability at scale. We show that alloying FeOOH with 4+ ions (My = Se, Sn, Ti, Hf) controls dissolution through the electronegatiity of the alloyed element. In 1 M KOH at 10 mA cm-2, all four alloys exhibited slower steady-state (8–48 h) Fe dissolution rates relative to pure FeOOH; and corresponding first-order rate constants fit to transient mass loss data (enabled by XRF) decrease as My becomes less electronegative. FeTiOOH (of particular note for its affordability relative to Ru and even Ni) dissolves about eight times more slowly than FeOOH; with the steady state rate of Fe mass loss suggesting an electrode half-life of about one month. The particular stability of more electropositive alloys (FeTiOOH and FeHfOOH) is achieved following a transient of about 8 h in which labile sites are stripped away (preferentially dissolved); and this restructuring manifests as an increase in the apparent charge transfer resistance and a decrease in the electrochemically active surface area as the electrode approaches steady state. As a result, more stable FeTiOOH and FeHfOOH anodes exhibit reduced OER activity relative to FeOOH (overpotentials 556, 412 and 370 mV). Nonetheless, these findings identify electropositive alloying as a route to stabilize earth-abundant Fe anodes for the oxygen evolution reaction. In a forthcoming publication, we will employ liquid-phase XPS to demonstrate that the alloy-modulated rates of Fe dissolution are mediated through two coupled effects: the oxidation state and hydroxyl coverage of the surface, and the electron density on lattice oxygens.
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BibTeX
@misc{hoseini2026engineering,
title = {{Engineering Fe-based OER electrocatalyst stability through alloy-driven modulation of Fe-O bond covalency and hydroxyl coverage}},
author = {Shayan Hoseini and Foroogh Khezeli and Ashley Head and Theodore W. Walker},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010067/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010067/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Engineering Fe-based OER electrocatalyst stability through alloy-driven modulation of Fe-O bond covalency and hydroxyl coverage
AU - Shayan Hoseini
AU - Foroogh Khezeli
AU - Ashley Head
AU - Theodore W. Walker
PY - 2026
DA - 2026/10/07
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010067/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010067/v1
AB - Fe-based oxyhydroxides are earth-abundant alternatives to costly Ir and Ru catalyst for the oxygen evolution reaction (OER), but their stability in alkaline electrolyte limits their applicability at scale. We show that alloying FeOOH with 4+ ions (My = Se, Sn, Ti, Hf) controls dissolution through the electronegatiity of the alloyed element. In 1 M KOH at 10 mA cm-2, all four alloys exhibited slower steady-state (8–48 h) Fe dissolution rates relative to pure FeOOH; and corresponding first-order rate constants fit to transient mass loss data (enabled by XRF) decrease as My becomes less electronegative. FeTiOOH (of particular note for its affordability relative to Ru and even Ni) dissolves about eight times more slowly than FeOOH; with the steady state rate of Fe mass loss suggesting an electrode half-life of about one month. The particular stability of more electropositive alloys (FeTiOOH and FeHfOOH) is achieved following a transient of about 8 h in which labile sites are stripped away (preferentially dissolved); and this restructuring manifests as an increase in the apparent charge transfer resistance and a decrease in the electrochemically active surface area as the electrode approaches steady state. As a result, more stable FeTiOOH and FeHfOOH anodes exhibit reduced OER activity relative to FeOOH (overpotentials 556, 412 and 370 mV). Nonetheless, these findings identify electropositive alloying as a route to stabilize earth-abundant Fe anodes for the oxygen evolution reaction. In a forthcoming publication, we will employ liquid-phase XPS to demonstrate that the alloy-modulated rates of Fe dissolution are mediated through two coupled effects: the oxidation state and hydroxyl coverage of the surface, and the electron density on lattice oxygens.
ER -