Ethanol Oxidation on Sn‐modified Pt Single‐Crystal Electrodes: New Mechanistic Insights from On‐line Electrochemical Mass Spectrometry

Abstract The modification of low‐index Pt single crystals with a submonolayer coverage of Sn enhances the electroactivity of the electrode for the ethanol oxidation process in perchloric acid solution. The optimum Sn coverage for ethanol oxidation depends on the Pt crystallography, found to be approximately 0.26, 0.48, and 0.58 for Pt(100), Pt(111), and Pt(110), respectively; the Sn/Pt(110) system being the surface that exhibits the highest activity. On‐line electrochemical mass spectrometry experiments show that both on Pt(111) and Pt(110), the presence of Sn enhances the oxidation of ethanol to acetaldehyde. The further oxidation of acetaldehyde is sensitive to the Pt surface structure: on Pt(110) there are sites able to break the C−C bond in acetaldehyde to form CO 2 , whereas on Pt(111) such sites are not available and acetaldehyde is oxidized further to acetic acid.