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Ab Initio Molecular Dynamic Simulations on Pd Clusters Confined in UiO-66-NH2

Chen, De-Li, Wu, Shengnan, Yang, Pengyong, He, Sihui, Dou, Li, Wang, Fang-Fang
The Journal of Physical Chemistry C 2017 v.121 no.16 pp. 8857-8863
chemical structure, coordination polymers, deformation, encapsulation, energy, molecular dynamics, simulation models, thermodynamics
The thermodynamically stable metal organic framework UiO-66-NH₂ has experimentally been demonstrated as an ideal platform to isolate metal clusters within its nanocages; however, the electronic structures and the dynamics of the encapsulated metal clusters are still unclear. Ab initio molecular dynamics simulations combined with density functional theory-based methods were employed to search the stable structures of Pdₙ@UiO-66-NH₂ composites, and their electronic properties were analyzed in detail. We found that the thermodynamics of the composites are highly correlated with charge transfer between the Pdₙ cluster and the UiO-66-NH₂ framework, as well as the deformation energy of the framework. In addition, both ab initio molecular dynamics simulations and density functional theory calculations show that the small Pd clusters can easily diffuse into the tetrahedral cage of UiO-66-NH₂ from the octahedral cage through the window connecting these two types of cages, with a small energy barrier.