Dopant driven tuning of the hydrogen oxidation mechanism at the pore/nickel/zirconia triple phase boundary

Albert M. Iskandarov, Tomofumi Tada

研究成果: ジャーナルへの寄稿学術誌査読

5 被引用数 (Scopus)

抄録

The effects of cation dopants in zirconia on the H2 oxidation mechanism at the pore/nickel/zirconia triple phase boundary (TPB) were theoretically examined. Y, Sc, Al, Ce, and Ca were considered as dopants, and on-boundary, O-migration, and H-migration reaction mechanisms were examined. Based on density functional theory calculations, Y as a dopant favored the on-boundary mechanism with water molecule formation within the immediate proximity of the TPB. The corresponding rate-limiting step is H transfer from the nickel surface to the boundary. In contrast, the on-boundary mechanism is not completed with the Al-, Sc-, and Ca-doped systems, due to the dissociation of water molecules at the boundary. In the Al-doped system, the O-migration mechanism is the major reaction pathway due to a low barrier for the rate-limiting step that corresponds to O transfer from zirconia to the nickel surface. The H-migration mechanism, which implies water molecule formation on the zirconia surface at a position distant from the boundary, should dominate at the Sc-, Ca-, and Ce-doped TPBs, with the lowest activation barrier at the Sc-doped TPB. The reasons for the switching of the reaction mechanisms depending on the dopant species are analyzed.

本文言語英語
ページ(範囲)12574-12588
ページ数15
ジャーナルPhysical Chemistry Chemical Physics
20
18
DOI
出版ステータス出版済み - 2018
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 物理学および天文学一般
  • 物理化学および理論化学

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