Potential dependence of composition and structure of electrodeposited Fe–Pt films

• Published in: Electrochimica acta Vol. 52; no. 1; pp. 194 - 199
• Main Authors: Leistner, K., Oswald, S., Thomas, J., Fähler, S., Schlörb, H., Schultz, L.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 05.10.2006; Elsevier
• Subjects: Alloy deposition; Chemistry; Electrochemistry; Electrodeposition; Exact sciences and technology; Fe–Pt electrodeposition; General and physical chemistry; Hydrogen evolution; Hydroxides; Oxygen; Study of interfaces; 68.35.Dv; Oxygen; 81.15Pq; Hydroxides; Alloy deposition; Fe–Pt electrodeposition; 75.70.-i; Hydrogen evolution; Hydrogen; Gas release; Potential; Iron alloy; X ray diffraction; Surface treatment; Operating conditions; Surface structure; Metal coating; Transmission electron microscopy; Platinum alloy; Morphology; Fe-Pt electrodeposition; Oxygen; Hydroxides; Hydrogen evolution; Alloy deposition; Electrodeposition; Chemical composition; Electrochemical reaction; Structure; Binary alloy; 68.35.Dv; 81.15Pq; 75.70.-i
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2006.04.058

Composition and structure of electrodeposited Fe–Pt–O films are investigated in dependence on deposition potential. At potentials positive to the hydrogen evolution, a solid solution of Pt with some Fe is present that can be explained by underpotential deposition of Fe. In the potential region where hydrogen evolution by proton reduction is a side reaction, oxygen is detected in the films. The O content scales with the Fe content and at least part of the Fe is oxidized. When applying more cathodic potentials, the fraction of Fe and O increases, grain size is reduced and an amorphous/nanocrystalline phase forms. The Fe content is pH dependent in this potential region. At even more cathodic potentials, overpotential deposition of Fe in the bcc structure sets in, the O content is reduced. The results are discussed with respect to thermodynamics in the Fe–Pt–(O) system. The concepts of underpotential deposition of Fe during Fe-Pt alloy deposition and of hydroxide formation due to a pH rise at the cathode are evaluated. These simple models can only partially describe the deposition process in agreement with the compositional and structural information obtained and a coupled mechanism is proposed.