Mechanisms for adsorption, dissociation and diffusion of hydrogen in hydrogen permeation barrier of 伪-Al₂O₃: The role of crystal orientation

详细信息    查看全文

• 作者：Guikai Zhang ; Sanping Dou ; Yongjie Lu ; Yan Shi ; Xinchun Lai ; Xiaolin Wang
• 关键词：Hydrogen adsorption ; Hydrogen diffusion ; 伪-Al2O3 ; Hydrogen permeation barrier ; Crystal orientation
• 刊名：International Journal of Hydrogen Energy
• 出版年：2 January, 2014
• 年：2014
• 卷：39
• 期：1
• 页码：610-619
• 全文大小：2200 K

文摘

The mechanisms of adsorption of hydrogen on 伪-Al₂O₃(1-102) surface and of its diffusion in bulk are investigated, using first principles thermodynamics and kinetics, and compared with similar results obtained for the diffusion of hydrogen on 伪-Al₂O₃(0001) surface. Because of the different oxygen environments on both surfaces, the H binding energies on the (1-102) surface are 0.3-1.2聽eV smaller than in the (0001) surface. The H₂ binding energies on (1-102) and (0001) surfaces are resembled. We have identified four main mechanisms, leading to dissociation of H₂, H migration on the surface, H diffusion into and inside the bulk. Equilibrium constant and activation barrier show that H₂ dissociation is the most favorable process and significant diffusion of H into the bulk can occur more readily from the (1-102) surface compared to the (0001) surface. Based on the hydrogen interaction with 伪-Al₂O₃(1-102) surface, a mechanism of 伪-Al₂O₃ suppressing H-permeation is identified.