CAJ | 학술논문

在密度泛函理论的框架下,采用嵌入点电荷簇模型研究了 O2在具有氧缺陷和镁缺陷 MgO(001)表面上的吸附 .用电荷自洽的方法确定了点电荷的值 .计算结果表明, O2倾向吸附在具有氧缺陷的 MgO(001)表面上 .通过和我们近期研究过的 O2在低配位的边、角上吸附结果相比较,发现具有氧缺陷的 MgO(001)表面更加有利于 O2的吸附和解离.Mü lliken电荷分析表明,电荷由底物向吸附的 O2反键轨道上转移是导致 O2键强削弱的主要原因 .势能曲线表明, O2在具有氧缺陷的 MgO(001)表面上发生解离所需要克服的能垒比在角阳离子端发生解离所需克服的能垒有大幅度降低.
재밀도범함이론적광가하,채용감입점전하족모형연구료 O2재구유양결함화미결함 MgO(001)표면상적흡부 .용전하자흡적방법학정료점전하적치 .계산결과표명, O2경향흡부재구유양결함적 MgO(001)표면상 .통과화아문근기연구과적 O2재저배위적변、각상흡부결과상비교,발현구유양결함적 MgO(001)표면경가유리우 O2적흡부화해리.Mü lliken전하분석표명,전하유저물향흡부적 O2반건궤도상전이시도치 O2건강삭약적주요원인 .세능곡선표명, O2재구유양결함적 MgO(001)표면상발생해리소수요극복적능루비재각양리자단발생해리소수극복적능루유대폭도강저.
The adsorption of O2 at oxygen vacancy site (F, F+ or F2+ site) and magnesium vacancy site (V, V- or V2- site) has been studied using cluster models embedding in a large array of point charges coupled to density functional method at B3LYP/6-31G(d) level. The value of point charges is determined by the self-consistent technique. The calculated results indicate that the MgO(001) surface with oxygen vacancies has more excellent catalyst structure contributing to the adsorptive-decomposition of O2 in comparison with the low-coordinated corner site in the previous study. The adsorption energies for O2 adsorbed on MgO(001) surface with oxygen vacancies are larger than those on MgO(001) surface with magnesium vacancies. Moreover, the MgO(001) surface with magnesium vacancies hardly exhibits catalytic reactivity toward O2 decomposition. The Mü lliken charge analysis illustrates that, for O2 adsorption on MgO(001) surface with oxygen vacancies, the electrons are transferred from the substrate to the adsorbed O2 and occupy the anti-bonding orbital, π of O2. Thus, the O- O bond strength is weakened. Potential energy curve shows that the energy barrier is considerably decreased for O2 adsorbed at oxygen vacancy site of MgO(001) surface when compared to that at corner site in our previous study.