Interfacial Charge Distribution Governing Electrochemical and Chemical Oxygen Evolution in Acidic Media
Abstract
Oxygen evolution reaction (OER) in acidic media is governed not solely by intrinsic catalytic activity, but by how anodic charge is distributed among competing interfacial pathways. Under strongly oxidizing conditions, metal dissolution, oxide formation, and oxygen-related redox processes proceed concurrently, obscuring the mechanistic origin of O2 evolution. Here, we combine atomic emission spectroelectrochemistry with operando respirometry to simultaneously quantify metal dissolution, electrical current, and dissolved O2 fluxes in real time for transition metals and binary alloys in acidic sulfate electrolyte. Direct mass-charge balance analysis reveals interfacial charge distribution as a unifying framework governing three distinct O2 evolution regimes: (i) dissolution-dominated behavior without OER, (ii) oxide-mediated electrochemical OER enabled by kinetically stabilized high-valence surface species, and (iii) transient storage or generation of oxidizing equivalents followed by chemically driven O2 formation upon potential relaxation. For example, Cr-rich passive matrices stabilize distinct interfacial oxidized states that either enable sustained electrochemical OER in Fe-Cr or promote delayed chemical O2 release in Ni-Cr, demonstrating that O2 evolution depends on the fate of anodic charge rather than on catalytic activity alone. The operando methodology further enables direct quantification of the average oxidation state of transient surface species without relying on spectroscopic assignment. These results establish interfacial charge distribution as a governing principle for O2 evolution under acidic conditions and provide a quantitative framework for resolving coupled electrochemical and chemical reaction pathways at highly oxidizing interfaces.
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BibTeX
@article{yuan2026interfacial,
title = {{Interfacial Charge Distribution Governing Electrochemical and Chemical Oxygen Evolution in Acidic Media}},
author = {Jinyi Yuan and Chenyang Xie and Fan Sun and Kevin Ogle and Junsoo Han},
journal = {ACS Electrochemistry},
year = {2026},
month = jul,
doi = {10.1021/acselectrochem.6c00249},
url = {https://hal.sorbonne-universite.fr/hal-05743757v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Interfacial Charge Distribution Governing Electrochemical and Chemical Oxygen Evolution in Acidic Media
AU - Jinyi Yuan
AU - Chenyang Xie
AU - Fan Sun
AU - Kevin Ogle
AU - Junsoo Han
PY - 2026
DA - 2026/07/20
JO - ACS Electrochemistry
DO - 10.1021/acselectrochem.6c00249
UR - https://hal.sorbonne-universite.fr/hal-05743757v1
AB - Oxygen evolution reaction (OER) in acidic media is governed not solely by intrinsic catalytic activity, but by how anodic charge is distributed among competing interfacial pathways. Under strongly oxidizing conditions, metal dissolution, oxide formation, and oxygen-related redox processes proceed concurrently, obscuring the mechanistic origin of O2 evolution. Here, we combine atomic emission spectroelectrochemistry with operando respirometry to simultaneously quantify metal dissolution, electrical current, and dissolved O2 fluxes in real time for transition metals and binary alloys in acidic sulfate electrolyte. Direct mass-charge balance analysis reveals interfacial charge distribution as a unifying framework governing three distinct O2 evolution regimes: (i) dissolution-dominated behavior without OER, (ii) oxide-mediated electrochemical OER enabled by kinetically stabilized high-valence surface species, and (iii) transient storage or generation of oxidizing equivalents followed by chemically driven O2 formation upon potential relaxation. For example, Cr-rich passive matrices stabilize distinct interfacial oxidized states that either enable sustained electrochemical OER in Fe-Cr or promote delayed chemical O2 release in Ni-Cr, demonstrating that O2 evolution depends on the fate of anodic charge rather than on catalytic activity alone. The operando methodology further enables direct quantification of the average oxidation state of transient surface species without relying on spectroscopic assignment. These results establish interfacial charge distribution as a governing principle for O2 evolution under acidic conditions and provide a quantitative framework for resolving coupled electrochemical and chemical reaction pathways at highly oxidizing interfaces.
SN - 2997-0571
SN - 2997-0571
ER -