WO3（001）极性表面及氢吸附特性的第一性原理研究

采用基于密度泛函理论的第一性原理方法对WO3 (001)的极性表面及其氢吸附特性进行了理论计算.通过对比WO表面和纯氧表面的表面化学势研究了两个极性表面的热力学稳定性,并分别计算了表面的几何结构和电子结构.结果表明:在贫氧环境中WO表面比较稳定,而在富氧环境中纯氧表面更稳定,WO表面和纯氧表面分别呈现n型半导体和p型半导体特性,表面原子通过调整W-O键长和键角实现表面弛豫.氢原子在两个极性表面不同吸附位置的计算表明:对WO表面和纯氧表面,W5c位和O1c位分别是稳定的吸附位置,且两者具有不同的反应特性.

First-principles Study on WO3(001) Polar Surface and Hydrogen Adsorption

Two different types of WO3(001) polar surface,namely WO surface and pure oxygen surface,were studied by a first-principles calculation method based on density functional theory(DFT).The thermodynamics stability of the two polar surfaces was analyzed by comparing the grand surface potential,which showed ambient oxygen concentration affected the surface stability substantially.WO surface was more stable on oxygen-rich conditions while less stable than pure oxygen surface in oxygen-poor environment.Electronic structure analysis demonstrated that the WO surface model showed an n-type semiconducting characteristics while the pure oxygen surface was p-type.Surface relaxation introduced variation of W-O bond length and angle.Different hydrogen adsorption sites on the two surfaces were calculated and adsorption energies were compared.The results proved that the W5c and O1c atoms were the most stable adsorption sites for WO surface and pure oxygen surface,respectively.The adsorption reaction mechanism was different for these two polar surfaces.