CO和CH_3O在Cu_2O(111)表面吸附特性及共吸附的理论研究

Theoretical Study on the Properties of CO and CH_3O Adsorption on Cu_2O(111) Surface and Co-adsorption

基于密度泛函理论,采用广义梯度近似方法结合周期平板模型,对Cu2O(111)非极性表面上CO和CH3O的吸附和共吸附进行了系统的研究.计算了CO以4种吸附模式和CH3O以O端在Cu2O(111)表面上的吸附,通过对不同吸附位置的吸附能、几何构型参数和Mulliken电荷的计算和比较发现,Cu2O(111)表面上配位未饱和铜离子(CuCUS)为CO的活性吸附位;配位饱和铜离子(CuCSA)为CH3O的活性吸附位.CO和CH3O吸附于Cu2O(111)表面后,表面弛豫现象明显改善.CO和CH3O与Cu2O(111)表面能够形成共吸附体系,CO和CH3O之间的相互作用力达到75.89 kJ/mol,为典型的化学作用,有助于促进CO和CH3O反应形成表面物种CH3OCO,计算结果与实验事实一致.

Based on density functional theory in the generalized gradient approximation,together with periodic slab model,CO and CH3O adsorption and co-adsorption on Cu2O（111） non-polar surface were systematically investigated.Four molecular orientations of CO and O-down orientation of CH3O over different adsorption sites,CuCUS,CuCSA,OSUF and OSUB of the Cu2O（111） surface were considered.The adsorption energy,geometrical parameter and Mulliken charge indicate that CuCUS is the active site for CO adsorption,CuCSA is the active site for CH3O adsorption.CO and CH3O adsorption mode improves the relaxation of Cu2O（111） surface.In co-adsorption system,the interaction between CO and CH3O is 75.89 kJ/mol,which help to product CH3OCO,the calculated results are in agreement with experimental facts.