NO在Rh(100)与(111)表面上吸附理论研究

基于slab模型,采用密度泛函理论研究了NO在Rh(100)和(111)表面上吸附的几何与电子结构.结果表明,在开放的(100)面和密堆积的(111)面上,优势吸附位分别是桥位和hcp位.在两表面上的优势吸附结构中,NO的吸附主要是其1π和5σ轨道分别与Rh的5s和4d态混合的结果.NO分子吸附后,均存在两种相同的电荷迁移过程:即NO的1π和5σ电子向金属表面的转移以及金属表面电子向NO的2π轨道上的反馈.这两种电子迁移均使得N-O键被活化,N-O键被消弱,N-O键长增加.

Theoretical Studies of NO Adsorption on Rh (100) and (111) Surfaces

The adsorption geometry and electronic structure of NO on Rh(100) and(111) surfaces have been studied based on the slab model by DFT method.The results indicate that NO prefers to the bridge site on the opened(100) surface and favors the 3-fold hollow site(hcp) on close-packed(111) surface.Binding of NO on both surfaces is mainly invoked by the recombination of NO 1π and 5σ with Rh 5s and 4d states respectively.In the absorption process of NO on both of the surfaces,two different charge transfer processes have been observed: the electron moves from NO1π and 5σ orbitals to the surfaces and the backdonation of the electrons from metal surface to the antibonding state 2π of NO.Both of these charge transfer processes activate and weaken the N-O bond as well as increase the N-O bond length.