Visualization of oscillatory behaviour of Pt nanoparticles catalysing CO oxidation
Visualization of oscillatory behaviour of Pt nanoparticles catalysing CO oxidation
复制标题
DOI：
10.1038/nmat4033
复制
发表时间：
2014-09-01
期刊：
影响因子：
41.2
通讯作者：
Helveg, S.
中科院分区：
文献类型：
--
作者：
Vendelbo, S. B.;Elkjaer, C. F.;Helveg, S.
许多催化反应在固定条件下表现出振荡行为。振荡通常归因于催化剂表面的动态变化。然而，到目前为止，对于由负载型纳米粒子组成的催化剂，很难确定这种关系。在这里，我们采用纳米反应器，利用时间分辨高分辨率透射电子显微镜、质谱法和量热法研究 Pt 纳米颗粒催化的振荡 CO 氧化。观察结果表明，CO 氧化的周期性变化与 Pt 纳米颗粒的周期性重塑是同步的。使用密度泛函理论和质量传递计算对振荡反应进行建模，并考虑 CO 吸附能和氧化速率与位点相关。我们发现，为了成功解释振荡，模型必须包含重构现象。因此，纳米反应器方法可以提供特定于表面位点的原子级信息。这将增进对催化及相关领域动态特性的理解。
Many catalytic reactions under fixed conditions exhibit oscillatory behaviour. The oscillations are often attributed to dynamic changes in the catalyst surface. So far, however, such relationships were difficult to determine for catalysts consisting of supported nanoparticles. Here, we employ a nanoreactor to study the oscillatory CO oxidation catalysed by Pt nanoparticles using time-resolved high-resolution transmission electron microscopy, mass spectrometry and calorimetry. The observations reveal that periodic changes in the CO oxidation are synchronous with a periodic refacetting of the Pt nanoparticles. The oscillatory reaction is modelled using density functional theory and mass transport calculations, considering the CO adsorption energy and the oxidation rate as site-dependent. We find that to successfully explain the oscillations, the model must contain the phenomenon of refacetting. The nanoreactor approach can thus provide atomic-scale information that is specific to surface sites. This will improve the understanding of dynamic properties in catalysis and related fields.