Kinetics and Mechanisms for the Adsorption, Dissociation, and Diffusion of Hydrogen in Ni and Ni/YSZ Slabs: A DFT Study
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- 作者：Meng Hsiung Weng ; Hsin-Tsung Chen ; Yao-Chun Wang ; Shin-Pon Ju ; Jee-Gong Chang ; M. C. Lin
- 刊名：Langmuir
- 出版年：2012
- 出版时间：April 3, 2012
- 年：2012
- 卷：28
- 期：13
- 页码：5596-5605
- 全文大小：558K
- 年卷期：v.28,no.13(April 3, 2012)
- ISSN：1520-5827
文摘
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鈥揥ang functional. The H2 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 H2 dissociation on both surfaces is calculated to be only 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.