Electrochemical Surface Composition of Iridium Oxide IrO2(110): Implications for the Oxygen Evolution Reaction
Ryan Lacdao Arevalo1,2, Jessiel Siaron Gueriba2, Hiroshi Nakanishi2,3,4
1School of Innovation and Sustainability, De La Salle University, Biñan City, Laguna 4024, Philippines.
Abstract:
The mechanism of the Oxygen Evolution Reaction (OER) on iridium oxide IrO2(110) highly depends on the stable structure of the surface under various electrochemical conditions. Through a first-principles-based Pourbaix diagram, we identified the stable di- and trioxygen surface terminations of IrO2(110) at electrode potentials relevant to the OER. Thermodynamics calculations revealed that the OER proceeds at an electrode potential where the surface is terminated with a hydrotrioxide species (-IrOOOH), which electrochemically decomposes to produce an oxygen gas. Our results point to a cyclic OER mechanism that is electrode potential-limited by the electrochemical dissociation of water to regenerate the hydrotrioxide-terminated surface. These findings provide new insights into the role of the initial surface composition of the catalyst in the reaction mechanism of the OER.
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