Surface Platinum Electrooxidation in the Presence of Oxygen
- General Motors
Understanding the influences of Pt surface oxides is crucial for elucidating the oxygen reduction reaction (ORR) in fuel cells, particularly with an eye toward the design of next-generation Pt-based electrocatalysts with improved activity. Although gaseous O{sub 2} is always present during the ORR, the majority of previous Pt surface oxide studies were conducted in the absence of O{sub 2} due to experimental limitations. In this study, multiple in situ techniques were applied to study the ORR on platinum in the presence of O{sub 2}. The thin channel flow Pt electrode and the electrochemical quartz microbalance (EQCM) techniques on Pt polycrystalline electrodes suggest that the influence of O{sub 2} in the electrolyte on mass change and charge transfer is negligible. The oxide formation followed a logarithm-growth behavior initiating as early as 0.2 s after potential steps. This suggests that no slow conversion of oxide species (e.g., between OH{sub ads} and O{sub ads}) takes place. Despite the negligible effect of O{sub 2} on the measured oxide coverage, steady-state X-ray absorption spectroscopy (XAS) measurements conducted on dispersed Pt nanoparticles suggested that, only when under O{sub 2}-sparging, place exchange between adsorbed oxide(s) and the Pt surface layer(s) initiated at potentials as low as 0.75 V. This is significantly lower than that observed in an O{sub 2}-free electrolyte (>1.1 V). The effects of O{sub 2} on adsorbed oxide species illustrate the complexities of applying model systems to the real world in order to arrive at a comprehensive description of both the oxygen reduction and the Pt dissolution processes.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- INDUSTRY
- OSTI ID:
- 1034939
- Journal Information:
- J. Phys. Chem. C, Vol. 116, Issue (5) ; 02, 2012; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- ENGLISH
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