ZnO[0001]表面及其氢吸附性能的第一性原理研究

First- principles Study of ZnO[0001]Surfaces and Hydrogen Adsorption Performance

采用密度泛函理框架下的第一性原理方法,计算了ZnO[0001]两种富裕表面吸附H的电子态密度和吸附能,探究了电子态密度和吸附能随表面厚度变化规律。结果表明,对于Zn富裕和O富裕的表面,随着表面层数的增加,费米能级附近的电子态密度变化很小,说明在一定范围内,增加吸附表面的厚度,对吸附性能的改善很小。Zn富裕表面吸附氢后,电子态密度主峰约向低能方向移动1eV,而强度变化不明显。而对于O富裕的表面,吸附H后,费米能级附近的电子态密度发生明显变化,导电能力增强,说明O富裕的表面对H具有较强的吸附能力。吸附能与层数之间的关系曲线表明:对于Zn富裕的表面,随着层数的增加,吸附能变化较小,分别为-0.37374eV和-0.37488eV,而O富裕的表面,吸附能变化较明显,从-0.32806eV到-0.48497eV,说明O富裕的表面,随着表面层数的增加,对H的吸附能力增强。

The electronic density of states and adsorption energy of Zn O[0001]surface are calculated by employing the first principles based on density functional theory,as well as investigate the influence of the surface thickness to the electronic density of states and adsorption energy. The results show that with increase of the surface layers of Zn rich and O rich surface,the electronic density of states near the Femi level has little change,which indicates that the surface thickness can＇t improve the adsorption performance. For the Zn rich surface adsorb hydrogen,the peak of density of states shifts to the lower energy orientation about 1 e V,while the amplitude did not change significantly. For O rich surface adsorb hydrogen,the density of states near the Femi level has an obvious change and the conductive ability enhanced,which reveal that oxygen rich surface has a strong adsorption ability to the hydrogen atoms. The function plot of the adsorption energy with the surface layers indicates that surface thickness has little effect on the Zn rich surface,the adsorption energy range from- 0. 37374 e V to- 0. 37488 e V,while for the oxygen rich surface,the adsorb energy has an obviously change,range from- 0. 32806 e V to- 0. 48497 e V,which reveal that increase the thickness of oxygen rich surface the adsorption energy can be enhanced.