Interfacial Charge Distribution Governing Electrochemical and Chemical Oxygen Evolution in Acidic Media
Year: 2026
Type: article
Abstract: The 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 that governs 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 and/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.
Source: ACS electrochemistry.
Institutions: Centre National de la Recherche Scientifique, Sorbonne Université, Laboratoire Interfaces et Systèmes Électrochimiques, Chimie ParisTech - PSL, Université Paris Sciences et Lettres, Jožef Stefan Institute, Jožef Stefan International Postgraduate School, Institut de Recherche de Chimie Paris
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7169808781