Mechanism for adsorption, dissociation and diffusion of hydrogen in hydrogen permeation barrier of alpha-Al2O3: A density functional theory study

作者：Zhang Guikai^*; Wang Xiaolin; Xiong Yifu; Shi Yan; Song Jiangfeng; Luo Deli

来源：International Journal of Hydrogen Energy, 2013, 38(2): 1157-1165.

DOI：10.1016/j.ijhydene.2012.10.108

• Hydrogen adsorption
• Hydrogen diffusion
• DFT alpha-Al2O3
• Hydrogen permeation barrier

Toward understanding physical interaction of hydrogen isotopes with alpha-Al2O3 barrier, adsorption, dissociation and diffusion of hydrogen in alpha-Al2O3(0001) slab have been investigated by density functional theory (OFT) and rate theory. H-2 molecule, with parallel configuration, preferentially absorbs on a top Al atom site of first atomic layer on alpha-Al2O3(0001) surface, while H atom strongly bonds at a top O atom site of the second atomic layer, H atoms recombine into molecules on top Al atom sites of the third atomic layer. The barrier for H-2 exothermic dissociation on surface is 0.79 eV. The potential energy pathways of H diffusion in alpha-Al2O3 are studied, predicting that H atom diffusion preferentially occurs via surface path rather than bulk path involving elementary reorientation and hopping steps. The surface-to-subsurface diffusion is significantly endothermic except for the surface and subsurface-to-bulk path. Mechanism, in well agreement with experimental result, of alpha-Al2O3 a resisting hydrogen permeation has proposed.

• 出版日期2013-1-24
• 单位中国工程物理研究院