Theoretical Study Of Adsorption And Reaction Mechanism On Ru,Cu And Au Surfaces

Adsorption and reaction of metal surface are considerable important due to its great potential in many industrial applications and in science study fields. The nature for metal surface decides to a great degree how a surface interacts with its environment, depending on surface defects, steps, kinkings, nano-sized islands, and adsorbates. Thus it would really be necessary to study the properties of bonding for atoms and molecules to metal surfaces at an atomic level.In this dissertation, the adsorption and reaction mechanism for atom or molecule on metal surfaces were studied by using5-parameters Morse potential and density functional theory. The main content of this dissertation is as following:Chapter1mainly introduces the background for adsorption and reaction of metal surface as well as the significance of their current research status and future prospects.Chapter2is about the computational methods and the software packages involved in this dissertation.Chapter3presented the study for adsorption, vibration, and diffusion of N atoms on Ru surfaces by means of5-MP method. The most stable adsorption states and the minimum energy diffusion pathways for atomic N on several Ru surface were obtained. It was also found that atomic N is adsorbed on the subsurface of Ru(1121), and it is easy for atomic N from surface to subsurface based on the low diffusion barrier.In the fourth chapter, the reaction mechanism for CO oxidation on Cu(311) was firstly studied by emplying density functional theory method. We found that O2is considerably reactive on the Cu(311) surface, and it is highly dependent on the orientation and site of the adsorbed oxygen molecule. Otherwise, CO oxidation on Cu(311) may occur through the Langmuir-Hinshelwood reaction of CO+Oâ†'CO2. While for direct reaction between CO and O2(CO+O2â†'CO2+O), the ready dissociation of O2together with an unfavorable barrier both suggest its infeasibility.In the fifth chapter, comprehensive oxidation mechanism for methanol on Au(111) in the presence of oxygen adatoms was investigated in terms of density functional theory study. For the first step, the α-H of methanol is eliminated to form CH3O on O/Au(111), and then αβ-H of CH3O is activated to generate HCHO. According to coverage of atomic O on Au(111), there are possible two reactive pathways for methanol on Au(111) owing to the different oxygen coverages:one is that the intermediate formaldehyde will be constantly oxidated to form formate at high oxygen coverage; the other is that formaldehyde and methoxy can couple to yield methyl formate at low oxygen coverage or without the presence of oxygen atom.