Surface segregation in a polycrystalline Pd₇₀Cu₃₀ alloy hydrogen purification membrane

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Surface Science

DOI:https://doi.org/10.1016/j.susc.2007.10.031· OSTI ID:1015109

Miller, James B. ^[1]; Matranga, Christopher ^[2]; Gellman, Andrew J. ^[1]

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1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Carnegie Mellon Univ., Pittsburgh, PA (United States)
2. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

X-ray photoelectron spectroscopy (XPS) and low energy ion scattering spectroscopy (LEISS) have been used to study the effects of various surface preparations and thermal treatments on the composition of the near-surface region (~7 atomic layers) and the topmost atomic layer of a polycrystalline Pd₇₀Cu₃₀ alloy. Palladium enrichment (relative to the bulk composition) is observed in the XPS-accessible near-surface region, but copper enrichment is observed in the topmost atomic layer. At temperatures above similar to 800 K, where the bulk, the near-surface region and the topmost atomic layer are likely in thermodynamic equilibrium, segregation to the top layer can be described in terms of a simple thermodynamic model. Temperature programmed desorption (TPD) of H₂ and CO from the annealed surfaces illustrates the impact of segregation and atomic distribution in the top layer on surface chemical activity.

• Research Organization: National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Fossil Energy (FE)
• OSTI ID: 1015109
• Report Number(s): NETL-TPR--1844
• Journal Information: Surface Science, Journal Name: Surface Science Journal Issue: 1 Vol. 602; ISSN 0039-6028
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

(LEIS)
(XPS)
58 GEOSCIENCES
LOW ENERGY ION SCATTERING
PDCU ALLOY
SEPARATION MEMBRANE
SURFACE SEGREGATION
X-RAY PHOTOELECTRON SPECTROSCOPY