Yu Xiaohu, Zhang Xuemei, Jin Lingxia, Feng Gang
Institute of Theoretical and Computational Chemistry, Shaanxi Key Laboratory of Catalysis, School of Chemical & Environment Sciences, Shaanxi University of Technology, Hanzhong 723000, China.
Phys Chem Chem Phys. 2017 Jul 5;19(26):17287-17299. doi: 10.1039/c7cp02760e.
By means of density functional theory calculations that account for the on-site Coulomb interaction via a Hubbard term (DFT+U), we systematically investigated CO adsorption on FeO surfaces at different coverages. It has been found that more than one CO can coadsorb on one surface iron atom on both Fe and Fe terminations of FeO(111). The uncapped oxygen atom is the active site for CO oxidation on both Fe and Fe terminations of FeO(111). For FeO(110), two CO molecules prefer to coadsorb on one surface iron atom on the A layer; CO prefers to adsorb at the bridge site of the surface octahedral iron atoms at low coverage, while CO prefers to adsorb at the surface tetrahedral iron atom at high coverage on the B layer. It has been found that the surface oxygen atom which is not coordinated to the tetrahedral iron atom is the active site for CO oxidation on the B termination of FeO(001). On the FeO surfaces, the formation of carbonate has been found to be very stable thermodynamically, which agrees well with experiments. The adsorption mechanism has been analyzed on the basis of projected density of states (PDOS).
通过采用包含哈伯德项（Hubbard term）以考虑在位库仑相互作用的密度泛函理论计算（DFT + U），我们系统地研究了不同覆盖度下CO在FeO表面的吸附情况。研究发现，在FeO(111)的Fe端和Fe端的一个表面铁原子上可以共吸附不止一个CO。未覆盖的氧原子是FeO(111)的Fe端和Fe端上CO氧化的活性位点。对于FeO(110)，两个CO分子更倾向于在A层的一个表面铁原子上共吸附；在低覆盖度下，CO更倾向于吸附在表面八面体铁原子的桥位，而在B层高覆盖度下，CO更倾向于吸附在表面四面体铁原子上。研究发现，未与四面体铁原子配位的表面氧原子是FeO(001)的B端上CO氧化的活性位点。在FeO表面，已发现碳酸盐的形成在热力学上非常稳定，这与实验结果非常吻合。基于投影态密度（PDOS）分析了吸附机理。
