Krösschell Rozemarijn D E, Hensen Emiel J M, Filot Ivo A W
Laboratory of Inorganic Materials & Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands.
J Phys Chem C Nanomater Interfaces. 2024 May 23;128(22):8947-8960. doi: 10.1021/acs.jpcc.4c00144. eCollection 2024 Jun 6.
Structure sensitivity in heterogeneous catalysis dictates the overall activity and selectivity of a catalyst whose origins lie in the atomic configurations of the active sites. We explored the influence of the active site geometry on the dissociation activity of CO by investigating the electronic structure of CO adsorbed on 12 different Co sites and correlating its electronic structure features to the corresponding C-O dissociation barrier. By including the electronic structure analyses of CO adsorbed on step-edge sites, we expand upon the current models that primarily pertain to flat sites. The most important descriptors for activation of the C-O bond are the decrease in electron density in CO's 1π orbital , the occupation of 2π anti-bonding orbitals and the redistribution of electrons in the 3σ orbital. The enhanced weakening of the C-O bond that occurs when CO adsorbs on sites with a step-edge motif as compared to flat sites is caused by a distancing of the 1π orbital with respect to Co. This distancing reduces the electron-electron repulsion with the Co -band. These results deepen our understanding of the electronic phenomena that enable the breaking of a molecular bond on a metal surface.
多相催化中的结构敏感性决定了催化剂的整体活性和选择性，其根源在于活性位点的原子构型。我们通过研究吸附在12个不同钴位点上的一氧化碳的电子结构，并将其电子结构特征与相应的碳 - 氧解离能垒相关联，探讨了活性位点几何结构对一氧化碳解离活性的影响。通过纳入对吸附在台阶边缘位点上的一氧化碳的电子结构分析，我们扩展了目前主要涉及平面位点的模型。碳 - 氧键活化的最重要描述符是一氧化碳1π轨道电子密度的降低、2π反键轨道的占据以及3σ轨道中电子的重新分布。与平面位点相比，当一氧化碳吸附在具有台阶边缘 motif 的位点上时，碳 - 氧键增强的弱化是由1π轨道相对于钴的距离增加引起的。这种距离增加减少了与钴能带的电子 - 电子排斥。这些结果加深了我们对使分子键在金属表面断裂的电子现象的理解。
