氧分子在Cu2O(111)表面吸附与解离的理论研究

本文采用密度泛函方法结合周期性平板模型，研究了氧原子和氧分子在完整和存在缺陷的Cu₂O(111)表面的吸附。计算结果表明氧原子倾向于吸附在配位饱和的Cu_CSA位，而对于氧分子，则强烈倾向于吸附在配位不饱和的Cu_CUS位。氧分子在含有氧空位的缺陷表面的优势吸附位为平行吸附于空位上方的桥位。过渡态的计算表明氧分子在缺陷表面的解离是一个活化能很小的放热过程。

A Theoretical Study of O2 Adsorption and Dissociation on Cu2O(111) Surface

Interaction of atomic and molecular oxygen with perfect and defective Cu₂O(111) surfaces has been studied by periodic density functional theory coupled with slab models. Different kinds of possible modes of O and O₂ adsorbed on Cu₂O(111) surface and possible dissociation pathways were calculated. Meanwhile, different electronic states, i.e., the singlet and the triplet states were considered in the computation. The optimization of the geometry, calculation of the adsorption energy, vibrational frequency and analysis of the Mulliken population were carried out. The results indicate that Cu_CSA site is slightly more favorable than Cu_CUS for O adsorption, and for O₂ adsorption over perfect surface, Cu_CUS site is the most advantageous position, especially for O₂ with end-on type. For O₂ adsorption over the deficient surface, it has a larger adsorption energy compared to O₂ adsorption over the perfect surface and the O-O bond strength is considerably weakened when O₂ lies flatly on the oxygen vacancy site and lies flatly over 1-vacancy bridge site. And the oxygen adspecies is characteristic of a classical O₂^- ion on perfect surface, whereas is O₂^2- ion on oxygen-deficient surface. The calculations for transition states show that the dissociation reaction of O₂ on deficient surface is highly exothermic with a very small barrier height.