Liu Xiao, Yang Jiaqiang, Shen Gurong, Shen Meiqing, Zhao Yunkun, Cho Kyeongjae, Shan Bin, Chen Rong
State Key Laboratory of Digital Manufacturing Equipment and Technology and School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, Hubei, People's Republic of China.
Nanoscale. 2019 Apr 25;11(17):8150-8159. doi: 10.1039/c8nr09054h.
The interfacial structure of metal-oxide composite catalysts plays a vital role in heterogeneous catalysis, which is crucial to the adsorption and activation of reactants. Herein, the interfacial effects of bare and Fe/Co/Ni doped SmMn2O5 mullite oxide supported Pt clusters on CO oxidation have been investigated by first-principles based microkinetics analysis. A robust formation of Pt/Mn2 trimer structures is demonstrated at the bifunctional interfaces irrespective of the Ptn cluster's size, which can provide spatially separated sites for CO adsorption and O2 dissociation. The binding strength of CO at the interfacial Pt sites is in the optimal range due to the charge transfer from Pt clusters to oxide, while the strong polarization of Mn2 dimers induced by Pt clusters with stable three-dimensional morphologies can lower the energy barrier of O2 dissociation. Based on the microkinetics analysis, the O2 dissociation is the rate-determining step in the full CO oxidation cycle, and the introduction of Mn-Fe hetero-dimers at the interface is predicted to further enhance the low temperature CO oxidation activity of Pt/SmMn2O5 catalysts.
金属氧化物复合催化剂的界面结构在多相催化中起着至关重要的作用，这对于反应物的吸附和活化至关重要。在此，通过基于第一性原理的微观动力学分析，研究了裸露的以及Fe/Co/Ni掺杂的SmMn2O5莫来石氧化物负载的Pt簇对CO氧化的界面效应。无论Ptn簇的大小如何，在双功能界面处都证明了Pt/Mn2三聚体结构的稳固形成，这可以为CO吸附和O2解离提供空间分离的位点。由于电荷从Pt簇转移到氧化物，CO在界面Pt位点的结合强度处于最佳范围，而具有稳定三维形态的Pt簇诱导的Mn2二聚体的强极化可以降低O2解离的能垒。基于微观动力学分析，O2解离是整个CO氧化循环中的速率决定步骤，并且预测在界面处引入Mn-Fe异二聚体将进一步提高Pt/SmMn2O5催化剂的低温CO氧化活性。
