| The thesis is devoted to the study of quantum-well (QW) states of Cu/Co-(Ni)/Cu stack and catalytic effect of nano-structure of gold employing first-principles calculation. The content consists of three parts, presented in chapter four, five and six, respectively.First, quantum-well (QW) states can be realized in Co/Cu slab system due to the confinement of electrons in the system. First principles calculations are preformed to investigate the effects of Ni or Co monolayer on the QW states in Co(100)/Cu(100) system. It is found that the monolayer Ni or Co as heteroge-neous spacer in Cu QW not only can disturb the QW states, but also can create new QW states because of the interfaces introduced, resulting in sub-well con-fining electrons. Monolayer Co and Ni spacer play different roles for modulating QW states due to their different electronic structures.Second, the absorption properties of the stretched gold thin film substrate on TiO2(110) surface were investigated. The absorption energy of O and O2 of freestanding gold thin films with different thickness were calculated. It is found strain can enhance the absorption energy of O atom and O2. Furthermore, the absorption energy of O2 on stretched Au(111) layer substrate on TiO2(110) was calculated, and it is found that there is no enhancement of absorption energy of O2 on stretched ordered Au(111) induced by substrate TiO2.Third, first-principles calculations are performed to study the interaction of medium sized amorphous cluster Au55 with small molecules, such as CO, O2. Complex structure [CO+O2](?)Au55, [CO2+O](?)Au55, [CO+O](?)Au55, [CO2](?)Au55 are compared from the view of total energy and absorption energy. It is found that CO and O2 can be co-adsorbed on Au55. The [CO2+O](?)Au55, [CO2](?)Au55 is favorable state compare to [CO+O2](?)Au55, [CO+O](?)Au55 respectively, which indicates that the CO oxidation can be catalyzed by the Au55. Comparisons be-tween [CO+O2](?)Aun, [CO2+O](?)Aun(n=8,32,55) indicate that, Au55 has com-petitive advantage for CO oxidation comparing on Aug and Au32.Besides, conceptual and theoretical models in pertinent fields were presented in the first three chapter. Chapter one and two introduce concepts and theoret-ical models of the Quantum-Well(QW) and catalysis properties, respectively. Chapter three gives a brief description of the density functional theory based first-principles calculation methods used in the thesis. |
