Mass transport in the PdCu phase structures during hydrogen adsorption and absorption studied by XPS under hydrogen atmosphere

Jiayi Tang, Susumu Yamamoto, Takanori Koitaya, Akitaka Yoshigoe, Takuma Tokunaga, Kozo Mukai, Iwao Matsuda, Jun Yoshinobu

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

We investigated mass transports during hydrogen adsorption and absorption processes of PdCu alloys that has advantages of higher hydrogen diffusivity and economically lower-cost than the other Pd-alloys. The research was made with a comparison of the well-known ordered phase of the bcc structure (the B2 phase) and a mixed phase of the fcc and B2 structures. In-situ ultrahigh vacuum X-ray photoelectron spectroscopy (UHV-XPS) and ambient pressure X-ray photoelectron spectroscopy (AP-XPS) using synchrotron radiation were carried out to trace the chemical states of the Pd and Cu atoms as a function of temperatures. It is newly elucidated that the initial adsorption and absorption processes were similar in the two phases, but a hydrogen diffusion rate to the bulk was apparently higher in the ordered phase than in the mixed one. We found the dynamics of the Pd and Cu atoms during the hydrogen adsorption/absorption processes largely depends on temperature. In the hydrogen atmosphere, the Pd atoms segregate at the surface below 373 K and Cu atoms segregate at the surface above 373 K, showing a reversal behavior. The present results agree well with the previous theoretical calculations and, thus, provide appropriate inputs toward developments of the industrial hydrogen permeation materials.

Original languageEnglish
Pages (from-to)419-426
Number of pages8
JournalApplied Surface Science
Volume480
DOIs
Publication statusPublished - 2019 Jun 30
Externally publishedYes

Keywords

  • Absorption
  • Adsorption
  • Ambient-pressure X-ray photoelectron spectroscopy
  • Hydrogen
  • PdCu alloy

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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