Environmental Engineering Reference
In-Depth Information
property of the Ru deposit above 0.25 ML of Ru that changes with coverage is the
growth of the island height from monoatomic to multilayered. Citing previous
works [Lu et al., 2002; Tong et al., 2002], we note that both Ru and Pt surface
atoms become less metallic with increasing Ru coverage, and both Pt and Ru atoms
need to donate DOS to a surface species. This species is defined as entrapped
oxygen between subsequent Ru layers deposited on Pt. The entrapped oxygen affects
the properties of the Pt/Ru edge, which, at high Ru coverage, is no longer a barrier
against CO entrance into the Ru domains to become oxidized. For purely monoatomic
adlayers of Ru on Pt, we conclude that a voltammetric resolution of the type depicted
in Fig. 12.18 should be found at high Ru coverage.
ACKNOWLEDGMENTS
This material is based upon work supported by the Army Research Office through a MURI
grant (DAAD19-03-1-0169) for fuel cell research to the Case Western Reserve University
by the Army Research Office under award Army W911NF-08-1-0309, by the National
Science Foundation under awards DMR 0504038 and NSF CHE06-51083, and by the Air
Force Office of Scientific Research under award FA9550-06-1-0235.
REFERENCES
Adzic RR, Tripkovic AV, O'Grady WE. 1982. Structural effects in electrocatalysis. Nature 296:
137 - 138.
Akemann W, Friedrich KA, Linke U, Stimming U. 1998. The catalytic oxidation of carbon mon-
oxide at the platinum/electrolyte interface investigated by optical second harmonic gener-
ation (SHG): Comparison of Pt(111) and Pt(997) electrode surfaces. Surf Sci 404: 571 - 575.
Akemann W, Friedrich KA, Stimming U. 2000. Potential-dependence of CO adlayer structures
on Pt(111) electrodes in acid solution: Evidence for a site selective charge transfer. J Chem
Phys 113: 6864 - 6874.
Arenz M, Mayrhofer KJJ, Stamenkovic V, Blizanac BB, Tomoyuki T, Ross PN, Markovic NM.
2005. The effect of the particle size on the kinetics of CO electrooxidation on high surface
area Pt catalysts. J Am Chem Soc 127: 6819 - 6829.
Babu PK, Lewera A, Chung J-H, Hunger R, Jaegermann W, Alonso-Vante N, Wieckowski A,
Oldfield E. 2007. Selenium becomes metallic in Ru-Se fuel cell catalysts; An EC-NMR and
XPS investigation. J Am Chem Soc 129: 15140 - 15141.
Backus EHG, Bonn M. 2005. A quantitative comparison between reflection absorption infrared
and sum-frequency generation spectroscopy. Chem Phys Lett 412: 152 - 157.
Bain CD. 1995. Sum-frequency vibrational spectroscopy of the solid liquid interface. J Chem
Soc Faraday Trans 91: 1281 - 1296.
Baldelli S, Markovic NM, Ross PN, Shen YR, Somorjai GA. 1999. Sum frequency generation
of CO on (111) and polycrystalline platinum electrode surfaces; Evidence for SFG invisible
surface CO. J Phys Chem B 103: 8920 - 8925.
Behrens RL, Lagutchev A, Dlott D, Wieckowski A. To be submitted.
Search WWH ::
Custom Search