Interfacial properties of ZrO 2 supported precious metal catalysts: A density functional study

Abstract

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 (Pt 4, Pd 4 and Rh 4) were deposited on the ZrO 2(1 1 1) surface. The Pt and Rh show much stronger interaction with the ZrO 2(1 1 1) surface than the Pd, indicating that the Pt–ZrO 2 and Rh–ZrO 2 interfaces are energetically more stable than the corresponding Pd–ZrO 2 interface. The effect of support relaxation on the adsorption energies reveals that a larger support relaxation effect can be observed on the Pt–ZrO 2 interface compared to the Pd–ZrO 2 interface. The Pt adsorption was associated with the largest support rearrangement with strong Pt–Zr interaction. The precious metal atoms on the ZrO 2(1 1 1) surface were positively charged. The electron transferred from the precious metal to the ZrO 2(1 1 1) surface was localized on the Zr atom. Moreover, electron exchanges on the Pt–ZrO 2 and Rh–ZrO 2 interfaces were more significant than that on the Pd–ZrO 2 interface. Additionally, the oxidization effects on the interaction between the precious metals and the ZrO 2 support were also investigated. The oxidization weakened the metal–metal interaction of the M 4 cluster, while the metal–ZrO 2 interaction was increased by the oxidization.