Infrared Reflection Absorption Spectroscopy of OH Adsorption on the Low Index Planes of Pt
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The adsorption of hydroxide (OHad) on Pt has been studied on the low index planes of Pt using infrared reflection absorption spectroscopy (IRAS) in electrochemical environments. We discuss the correlation between the integrated band intensity of the bending mode of OH of Pt–OH (δ PtOH) and the charge density of the oxide formation of Pt. The band of δ PtOH is observed around 1100 cm−1, and the onset potential depends on the surface structure. The onset potential of δ PtOH on Pt(110) and Pt(100) overlaps with the hydrogen adsorption/desorption potential region. The order of the integrated band intensity of δ PtOH at 0.9 V vs RHE is opposite to the order of the oxygen reduction reaction (ORR) activity. This finding supports that the OHad is one of the species deactivating the ORR.
KeywordsIRAS Electrochemical environments Adsorption of hydroxide Oxygen reduction reaction