Fan Qi-Yuan, Wang Ye, Cheng Jun
State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
J Phys Chem Lett. 2021 Apr 29;12(16):3891-3897. doi: 10.1021/acs.jpclett.1c00506. Epub 2021 Apr 15.
Small cluster catalysts are highly size-dependent and exhibit complex structural dynamic effects during catalytic reactions. Understanding their structural dynamics is of great importance in tuning the catalytic performances of small clusters that widely exist in supported catalysts. However, very little is known about the size dependence of the dynamic effect of small clusters. In this work, we systematically study the free energies and barriers of catalytic dissociation of CO at different temperatures on dynamical Cu clusters with different sizes by molecular dynamics. The reaction shows an abnormal entropic effect on Cu clusters, and more interestingly, it shows size sensitivity. On the Cu cluster, the entropy curve shows a reverse peak shape with increasing temperature, and it is surprising to find that it has a complex pulse shape on the Cu cluster. The detailed analysis shows that such temperature dependences can be attributable to the nontrivial behaviors of adsorption-induced phase transitions of the subnanometer Cu clusters during the dissociation of CO. Our work not only demonstrates the complexity of the temperature dependence of the surface reaction on cluster sizes but also provides useful insight into the phase transition catalysis of dynamic clusters.
小团簇催化剂高度依赖尺寸，并在催化反应过程中表现出复杂的结构动力学效应。了解它们的结构动力学对于调节负载型催化剂中广泛存在的小团簇的催化性能至关重要。然而，关于小团簇动力学效应的尺寸依赖性却知之甚少。在这项工作中，我们通过分子动力学系统地研究了不同温度下不同尺寸的动态铜团簇上CO催化解离的自由能和势垒。该反应对铜团簇表现出异常的熵效应，更有趣的是，它表现出尺寸敏感性。在铜团簇上，熵曲线随温度升高呈现出反向峰值形状，并且令人惊讶地发现它在铜团簇上具有复杂的脉冲形状。详细分析表明，这种温度依赖性可归因于亚纳米铜团簇在CO解离过程中吸附诱导的相变的非平凡行为。我们的工作不仅证明了表面反应的温度依赖性对团簇尺寸的复杂性，而且还为动态团簇的相变催化提供了有用的见解。
