کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
11027024 | 1666335 | 2019 | 50 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Effect of vacancy on adsorption/dissociation and diffusion of H2S on Fe(1â¯0â¯0) surfaces: A density functional theory study
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
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چکیده انگلیسی
Vacancy defects on an iron surface have a great influence on the occurrence of hydrogen embrittlement. The adsorption/dissociation mechanism of H2S and the diffusion behavior of H atoms were calculated by first-principles spin-polarization density functional theory (DFT) on defect-free and vacancy-defective Fe(1â¯0â¯0) surfaces. The results show that the maximum dissociation energy barriers of H2S on the Fe(1â¯0â¯0) surface of defect-free and first-layer vacancy-defective Fe are 0.35 and 0.17â¯eV, respectively, indicating that the reactivity of the vacancy-defective Fe(1â¯0â¯0) surface is moderately increased. The existence of vacancy defects changes the preferential H atom diffusion entrance to the subsurface and shortens the diffusion path. For H diffusion in bulk Fe(1â¯0â¯0), it is found that H atoms diffuse via a tortuous path from one tetrahedral-site to a neighboring tetrahedral-site rather than diffusing through a linear trajectory. Moreover, the previously suggested path via the octahedral site is excluded due to its higher barrier and the rank of the saddle point. Diffusion barriers computed for H atom penetration from the surface into the inner-layers are approximately 0.54â¯eV (except for second-layer vacancy defects), which are all greater than the activation energy for dissociation of H2S on the Fe(1â¯0â¯0) surfaces. This suggests that H diffusion is more probable than H2S dissociation as the rate-limiting step for hydrogen permeation into the bulk Fe(1â¯0â¯0).
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Surface Science - Volume 465, 28 January 2019, Pages 833-845
Journal: Applied Surface Science - Volume 465, 28 January 2019, Pages 833-845
نویسندگان
Xiangli Wen, Pengpeng Bai, Zongying Han, Shuqi Zheng, Bingwei Luo, Teng Fang, Weiyu Song,