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采用密度泛函理论系统研究了超薄氧化物膜/金属体系FeO/Pt和FeO2/Pt及其表面不同区域(FCC,HCP和TOP)的几何结构、电子性质及氧的活性.研究发现,表面O-Fe高度差δz作为一个重要的特征结构参数直接影响局域表面静电势和表面氧的结合能:δz越大,静电势越大,氧的结合能越弱.计算发现,在FeO/Pt体系中,δz顺序为FCC>HCP>TOP,而FeO2/Pt中是FCC>TOP>HCP.此外,在FeO/Pt中,电荷转移方向是从氧化物膜到衬底,Fe的表观价态为+2.36,表面功函较纯Pt(111)的变化可忽略;而FeO2/Pt中,电荷转移的方向是从衬底到氧化物,Fe的表观价态为+2.95,表面功函较纯Pt增加1.24eV.进一步分析了电荷转移和表面偶极对电子性质的作用机制.这些研究结果对于认识超薄氧化物薄膜对表面几何结构、电子性质、表面氧活性的调制具有重要的启示意义.
The geometrical structures, electronic properties and oxygen activity of ultra-thin oxide film / metal system FeO / Pt and FeO2 / Pt and their different surface areas (FCC, HCP and TOP) were investigated by using density functional theory O-Fe height difference δz as an important characteristic structure parameter directly affects the binding energy of local surface electrostatic potential and surface oxygen: the larger the δz, the greater the electrostatic potential, the weaker the binding energy of oxygen. Calculations show that in the FeO / Pt In the system, δz order is FCC> HCP> TOP and FCC> TOP> HCP in FeO 2 / Pt. In addition, in FeO / Pt, the charge transfer direction is from the oxide film to the substrate, Is +2.36, the surface work function is less than the pure Pt (111). In FeO2 / Pt, the charge transfer direction is from the substrate to the oxide. The apparent valence state of Fe is +2.95. Pure Pt increased by 1.24eV. The mechanism of charge transfer and surface dipole on the electronic properties were further analyzed.These results are of great significance for understanding the modulation of surface geometry, electronic properties and surface oxygen activity of ultrathin oxide films .