Hydrogen Adsorption on Co Surfaces: A Density Functional Theory and Temperature Programmed Desorption Study
Hydrogen Adsorption on Co Surfaces: A Density Functional Theory and Temperature Programmed Desorption Study
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DOI：
10.1021/cs2006586
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发表时间：
2012-05
期刊：
影响因子：
12.9
通讯作者：
Pieter van Helden;J. van den Berg;C. J. Weststrate
中科院分区：
文献类型：
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作者：
Pieter van Helden;J. van den Berg;C. J. Weststrate
采用密度泛函理论（DFT）计算和程序升温脱附（TPD）实验研究了氢在Co（111）和Co（100）表面的吸附.氢在Co（111）面上的吸附与覆盖度有关，计算的吸附能与Co（0001）面上的吸附能非常相似。在Co（111）/（0001）表面上的实验吸附饱和覆盖率为θmax <$0.5 ML，而DFT预测θmax <$1.0 ML。DFT计算表明，当覆盖度接近θ = 0.5ML时，预吸附氢将在动力学上阻碍吸附过程，从而导致这种差异。Co（100）表面的吸附在θ = 1.00 ML范围内与覆盖度无关，这与Ni（100）表面的观察结果相反。氢原子在Co（111）和Co（100）表面上都具有低的扩散势垒。脱附的微观动力学分析，模拟预期的TPD实验，表明在Co（111）表面上预期有两个TPD峰，而在Co（100）表面上预期只有一个。
Density functional theory (DFT) calculations and temperature programmed desorption (TPD) experiments were performed to study the adsorption of hydrogen on the Co(111) and Co(100) surfaces. On the Co(111) surface, hydrogen adsorption is coverage dependent and the calculated adsorption energies are very similar to those on the Co(0001) surface. The experimental adsorption saturation coverage on the Co(111)/(0001) surface is θmax ≈ 0.5 ML, although DFT predicts θmax ≈ 1.0 ML. DFT calculations indicate that preadsorbed hydrogen will kinetically impede the adsorption process as the coverage approaches θ = 0.5 ML, giving rise to this difference. Adsorption on Co(100) is coverage independent up to θ = 1.00 ML, contrasting observations on the Ni(100) surface. Hydrogen atoms have low barriers of diffusion on both the Co(111) and Co(100) surfaces. A microkinetic analysis of desorption, simulating the expected TPD experiments, indicated that on the Co(111) surface two TPD peaks are expected, while on the Co(100) onl...