Influence of Substrate Steps on the Catalytic Properties of Pt Layers: The Ethanol Electrooxidation Reaction

• Published in: Chemphyschem Vol. 15; no. 17; pp. 3864 - 3870
• Main Authors: Prieto, Mauricio J., Tremiliosi-Filho, Germano
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.12.2014; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: Catalysis; Chemistry; electrocatalysis; Electrochemistry; Ethanol; Exact sciences and technology; Fourier transforms; General and physical chemistry; gold; Kinetics and mechanism of reactions; platinum; Spectrum analysis; stepped surfaces; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Substrate; Electrocatalysis; Gold; Catalytic reaction; Ethanol; Platinum; Alkanol; Alcohol; stepped surfaces; Transition metal; Oxidation; Electrochemical reaction; gold; platinum; electrocatalysis; ethanol
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201402377

The ethanol oxidation reaction (EOR) is investigated on Pt/Au(hkl) electrodes. The Au(hkl) single crystals used belong to the [n(111)x(110)] family of planes. Pt is deposited following the galvanic exchange of a previously deposited Cu monolayer using a Pt2+ solution. Deposition is not epitaxial and the defects on the underlying Au(hkl) substrates are partially transferred to the Pt films. Moreover, an additional (100)‐step‐like defect is formed, probably as a result of the strain resulting from the Pt and Au lattice mismatch. Regarding the EOR, both vicinal Pt/Au(hkl) surfaces exhibit a behavior that differs from that expected for stepped Pt; for instance, the smaller the step density on the underlying Au substrate, the greater the ability to break the CC bond in the ethanol molecule, as determined by in situ Fourier transform infrared spectroscopy measurements. Also, we found that the acetic acid production is favored as the terrace width decreases, thus reflecting the inefficiency of the surface array to cleave the ethanol molecule. Pt‐modified Au vicinal surfaces are tested for ethanol electrooxidation. The formation of a new (100)‐type site is observed, which is probably the result of the lateral strain suffered by the Pt film. CC bond cleavage is inferred from in situ Fourier transform infrared results suggesting that the reactiveness of the underlying Au monoatomic steps is transferred to the catalytically active film.