Microcalorimetry of oxygen adsorption on fcc Co{110}.
Microcalorimetry of oxygen adsorption on fcc Co{110}.
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DOI：
10.1039/c2cp40549k
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发表时间：
2012-05
期刊：
影响因子：
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通讯作者：
K. Liao;V. Fiorin;S. Jenkins;D. King
中科院分区：
文献类型：
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作者：
K. Liao;V. Fiorin;S. Jenkins;D. King
使用单晶吸附量热法 (SCAC) 在 300 K 下测量了氧在 fcc Co{110} 上的覆盖率依赖吸附热和粘附概率。初始吸附与低覆盖度下的解离化学吸附一致，随后在高于 0.6 ML 覆盖度时形成氧化物。 633 kJ mol(-1) 的初始吸附热与在其他铁磁金属表面（例如镍和铁）上通过量热法测量的热值相似。随着覆盖率的增加，吸附热和粘附概率迅速下降直至氧化开始。正如已经在其他氧-金属表面系统中观察到的那样，强大的横向吸附原子排斥力导致从化学吸附状态转变为更高覆盖率的氧化膜形成。氧化物形成开始时的热量为475 kJ mol(-1)，这与CoO微晶的形成一致。从成核和岛生长以及 Mott-Cabrera 机制方面讨论了氧化膜的形成，后者通过与镍和铁氧化情况相比相对恒定的吸附热和粘附概率来证明。
The coverage dependent heats of adsorption and sticking probabilities for oxygen on fcc Co{110} have been measured at 300 K using single crystal adsorption calorimetry (SCAC). Initial adsorption is consistent with dissociative chemisorption at low coverage followed by oxide formation above 0.6 ML coverage. The initial heat of adsorption of 633 kJ mol(-1) is similar to heat values calorimetrically measured on other ferromagnetic metal surfaces, such as nickel and iron. As the coverage increases, the heat of adsorption and sticking probability drop very rapidly up to the onset of oxidation. As already observed for other oxygen-metal surface systems, strong lateral adatom repulsions are responsible for the transition from the chemisorption regime to oxide film formation at higher coverage. The heat of oxide formation at the onset is 475 kJ mol(-1), which is consistent with the formation of CoO crystallites. The oxide film formation is discussed in terms of nucleation and island growth, and the Mott-Cabrera mechanisms, the latter being evidenced by the relatively constant heat of adsorption and sticking probability in contrast to the nickel and iron oxidation cases.