Size-Dependent Dissociation of Carbon Monoxide on Cobalt Nanoparticles
Size-Dependent Dissociation of Carbon Monoxide on Cobalt Nanoparticles
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DOI：
10.1021/ja3105889
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发表时间：
2013-02-13
影响因子：
15
通讯作者：
Salmeron, Miguel
中科院分区：
文献类型：
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作者：
Tuxen, Anders;Carenco, Sophie;Salmeron, Miguel
利用软X射线吸收光谱（XAS）原位研究了一氧化碳分子在粒径为4 ~ 15 nm的钴纳米颗粒上的吸附和解离过程。大部分CO分子以分子形式吸附在纳米颗粒表面，但也有一些发生解离吸附，导致纳米颗粒表面形成氧化物物种。我们发现，CO进行解离的倾向严重依赖于Co纳米颗粒的大小。事实上，CO分子在较大的纳米颗粒（15 nm）上比在较小的颗粒（4 nm）上更有效地解离。我们进一步观察到吸附的CO在暴露于氢气时的解离速率的强烈增加，清楚地表明钴纳米颗粒上的CO解离是由氢气辅助的。我们的研究结果表明，钴纳米粒子解离氢的能力是决定钴纳米粒子在费托合成反应中的反应性的主要参数。
In situ soft X-ray absorption spectroscopy (XAS) was employed to study the adsorption and dissociation of carbon monoxide molecules on cobalt nanoparticles with sizes ranging from 4 to 15 nm. The majority of CO molecules adsorb molecularly on the surface of the nanoparticles, but some undergo dissociative adsorption, leading to oxide species on the surface of the nanoparticles. We found that the tendency of CO to undergo dissociation depends critically on the size of the Co nanoparticles. Indeed, CO molecules dissociate much more efficiently on the larger nanoparticles (15 nm) than on the smaller particles (4 nm). We further observed a strong increase in the dissociation rate of adsorbed CO upon exposure to hydrogen, clearly demonstrating that the CO dissociation on cobalt nanoparticles is assisted by hydrogen. Our results suggest that the ability of cobalt nanoparticles to dissociate hydrogen is the main parameter determining the reactivity of cobalt nanoparticles in Fischer-Tropsch synthesis.