NO及NH_3在MnO表面吸附行为的计算研究

Computational Study on the Adsorption Behavior of NO and NH_3 Molecules on the MnO Surface

选取MnO(111)、(110)及(001)晶面超晶胞做为反应表面模型,运用DFT中GGA的PBE方法,探讨了NO及NH3分子在MnO(111)、MnO(110)、MnO(001)面上的吸附行为,结果表明,NO及NH3均在MnO(111)面的top-Mn位上较易吸附,且NO吸附能较大。通过Mulliken布局数及态密度分析发现,在NO及NH3的吸附过程中,气体分子与吸附衬底之间发生了较强的相互作用。NO吸附时电子从衬底转移到N原子上,得到NO-阴离子结构,而NH3吸附后电子则从N原子转移到衬底上。Mn原子通过3d、4s轨道与NO及NH3中的N形成了化学键,使吸附更加稳定。

The density functional theory （DFT） based on GGA-PBE method has been used to study the adsorption be-havior of NO and NH3 molecules on the MnO （111） . （110） and （001） surface. The results showed that both NO and NH3 were easily to be adsorbed on the MnO（111） surface of the top-Mn site and the adsorption energy of NO was bigger. The analysis of the Mulliken charges and the density of state （DOS） reflected that during the adsorption of NO and NH3, there was a strong interaction occurred between the gas molecule and the adsorption substrate. The electron moved from the adsorption substrate to the Nitrogen atom during the NO adsorption progress and obtained the NO anion struc-ture. However, the electron transferred from the Nitrogen atom to the substrate after the adsorption of NH3. The Manga- nese atom formed a chemical bond with Nitrogen atom with 3d and 4s orbitals while NO and NH3 were absorbed.