Felício-Sousa Priscilla, Andriani Karla F, Da Silva Juarez L F
São Carlos Institute of Chemistry, University of São Paulo, PO Box 780, 13560-970, São Carlos, São Paulo, Brazil.
Phys Chem Chem Phys. 2021 Apr 14;23(14):8739-8751. doi: 10.1039/d0cp06091g. Epub 2021 Mar 30.
Here, we report a theoretical investigation, based on density functional theory calculations, into the role of the occupation d-states on the adsorption properties of CH, CO, H and CHOH on 3d 13-atom transition-metal (TM) clusters (TM = Fe, Co, Ni, Cu). Except for Cu, a gradual increase in the occupation of the d-states, i.e., from Fe to Ni, increases the magnitude of the adsorption energy almost linearly for the H/TM and CO/TM systems, which can be explained by the enhancement of the sp-d hybridization due to the shift of the d-states towards the highest occupied molecular orbital (HOMO). For Cu, the d-states are located well below the HOMO, which reduces the sp-d hybridization, and hence, a smaller adsorption energy is obtained. However, this picture does not hold for CH/TM and CHOH/TM, where the adsorption energy has nearly the same value for all TM clusters, which can be explained by electrostatic effects such as local polarization of the molecules and nearby TM atoms, and hence, the basic features of physisorption systems. Based on the electron density difference, the polarization effects are slightly larger for systems with empty d-states.
在此，我们基于密度泛函理论计算，报告了一项关于占据d态对CH、CO、H和CHOH在13个原子的3d过渡金属（TM）簇（TM = Fe、Co、Ni、Cu）上吸附性质作用的理论研究。除了Cu之外，对于H/TM和CO/TM体系，d态占据的逐渐增加（即从Fe到Ni）几乎线性地增加了吸附能的大小，这可以通过d态向最高占据分子轨道（HOMO）移动导致的sp-d杂化增强来解释。对于Cu，d态位于HOMO下方较远位置，这降低了sp-d杂化，因此获得较小的吸附能。然而，对于CH/TM和CHOH/TM体系，这种情况并不成立，其中所有TM簇的吸附能几乎相同，这可以通过分子和附近TM原子的局部极化等静电效应来解释，因此是物理吸附体系的基本特征。基于电子密度差，对于具有空d态的体系，极化效应略大。
