Interfacial properties of ZrO2 supported precious metal catalysts: A density functional study

In this study, we performed periodic DFT calculations to clarify the interfacial properties of zirconia-supported precious metal catalyst systems. Atomic precious metals (Pt, Pd and Rh) and four-metal-atom clusters (Pt4, Pd4 and Rh4) were deposited on the ZrO2(1 1 1) surface. The Pt and Rh show much stronger interaction with the ZrO2(1 1 1) surface than the Pd, indicating that the Pt–ZrO2 and Rh–ZrO2 interfaces are energetically more stable than the corresponding Pd–ZrO2 interface. The effect of support relaxation on the adsorption energies reveals that a larger support relaxation effect can be observed on the Pt–ZrO2 interface compared to the Pd–ZrO2 interface. The Pt adsorption was associated with the largest support rearrangement with strong Pt–Zr interaction. The precious metal atoms on the ZrO2(1 1 1) surface were positively charged. The electron transferred from the precious metal to the ZrO2(1 1 1) surface was localized on the Zr atom. Moreover, electron exchanges on the Pt–ZrO2 and Rh–ZrO2 interfaces were more significant than that on the Pd–ZrO2 interface. Additionally, the oxidization effects on the interaction between the precious metals and the ZrO2 support were also investigated. The oxidization weakened the metal–metal interaction of the M4 cluster, while the metal–ZrO2 interaction was increased by the oxidization.