O_2在Pd_2@Au/Pd(100)表面上分解机理研究

Theoretical Studies of O_2 Decomposition Mechanism on Pd_2 @Au/Pd(100)

采用密度泛函理论,在slab模型下,研究了O2分子在Pd2@Au/Pd(100)表面上的吸附与分解.结果表明:O2分子优先吸附于Pd-Pd桥位,O-O键轴平行于表面.O2分子通过其3σg和1πu轨道向表面转移电荷,又通过其1πg轨道接受来自表面的电子,净的结果是每个O原子得到了0.22e.合金表面暴露出来的Pd二聚体团簇为催化分解O2的活性中心.O2分子在Pd2@Au/Pd(100)表面上分解时,首先需要在扩散中断裂O-O键,然后经过一系列O原子的扩散过程,达到稳定的产物结构.

Density functional theory（DFT） and slab model were employed to study the adsorption and decomposition of O2 on Pd2 @Au/Pd（100） surface. O2 with its O-O bond parallel to the surface, preferred the Pd-Pd bridge site. The mixing of O2 36g and 1πu with Pd d states results in the electron transfer from O2 to Pd atoms, on the contrary, the interaction between O2 1πg and Pd d orbitals will cause charge flow from Pd to O2. In the end, each O atom will accept 0.22 e. As a catalytic active center, the exposed Pd binary cluster will decompose O2. The possible decomposition path is the O-O bond breakage when it diffuses toward to the hollow site and then the O atoms experience a series diffusing process and finally anchored to the stable sites.