Title: Kinetics and Mechanisms for the Adsorption, Dissociation, and Diffusion of Hydrogen in Ni and Ni/YSZ Slabs: A DFT Study
Authors: Weng, Meng Hsiung
Chen, Hsin-Tsung
Wang, Yao-Chun
Ju, Shin-Pon
Chang, Jee-Gong
Lin, M. C.
Department of Applied Chemistry
Institute of Molecular science
Issue Date: 3-Apr-2012
Abstract: The adsorption, dissociation, and diffusion of hydrogen in Ni(100) and Ni(100)/YSZ(100) slabs with two different interfaces (Ni/cation and Ni/O interface) have been studied by the density functional theory (DFT) with the Perdew-Wang functional. The H-2 molecule is found to preferentially absorb on a Top (T) site with side-on configuration on the Ni(100) surface, while the H-atom is strongly bound at a fcc Hollow (H) site. The barrier for the H-2 dissociation on both surfaces is calculated to be only similar to 0.1 eV. The potential energy pathways of H diffusion on pure Ni and Ni/YSZ with the two different interfaces are studied. Our calculated results show that the H-atom diffusion occurs via surface path rather than the bulk path. For the bulk path in Ni/YSZ, H-atom migration can occur more readily at the Ni/cation interface compared to the Ni/O interface. The existence of vacancy in the interface region is found to improve the mobility of H-atoms at the interface of Ni/YSZ slab. The rate constants for hydrogen dissociation and diffusion in pure Ni and Ni/YSZ are predicted.
URI: http://hdl.handle.net/11536/16047
ISSN: 0743-7463
Volume: 28
Issue: 13
End Page: 5596
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