CO和NO在CuO及CU_2O(110)表面吸附选择规律研究

Quantum Chemical Studies of the Chemisorbed Selectivity of CO and NO on CuO and Cu_2O(110) Surfaces

采用离散变分Xα方法分别计算了CO和NO以C（或N）端顶位吸附在CuO（110）及Cu2O（110）表面上的基态势能曲线，结果表明：CO在Cu2O表面上的吸附强，而在CuO表面上的吸附弱；NO则在CuO表面上吸附强，在Cu2O表面上吸附弱．它们的吸附能的大小顺序为：CuO－NO＞Cu2O－CO＞Cu2O－NO＞CuO－CO．对于CuO－NO（或CO）吸附体系，主要是Cu的3d轨道与吸附分子的2π轨道间的相互作用；对于Cu2O－CO（或NO）吸附体系，办主要是吸附质分子的5σ及2π分子轨道与其顶位Cu1的4s及4p轨道和侧位Cu2的3d轨道相互作用．本文通过吸附势能曲线、态密度分析、成键分析及电荷转移量和方向等方面对实验现象做了合理的解释．

The characteristics of CO and NO adsorptions on surfaces of CuO(110) andCu2O(110) have been studied by using Self- Consistent-Charge Discrete Variational XαMethod (SCC-DV-Xα for short). The calculated results show that the molecules COand NO are perpendicularly adsorbed on cuprous of Cu2O and cupric of CuO bondedwith C and N atoms respectively. The order of chemisorption potential of the four ad sorbed systems are: CuO-NO>Cu2O-CO>Cu2O-NO>CuO-CO. For CO or NO moleculechemisorbed on cupric oxide, the chemisorbed bonds are mainly contributed by the inter actions of 3d orbitals of cupric with 2π molecular orbital (MO) of the adsorbates. Whilefor CO or NO molecule chemisorbed on cuprous oxide , the chemisorbed bonds are mainlyformd by the interactions of 3d orbitals of the top site Cu+ and 4s, 4p orbitals of the sidesite Cu+ with 5a and 2π MO of adsorbates. These conclusions coincide with the experi mental observations[1-7]. The selective chendsorptions of CO and NO on the (110) surfaceof cupric and cuprons oaldes are discussed by analysis of the potential curve, density ofstates (DOS), bonding characters and the electrons transfers.