Insight into the effect of CaMnO3 support on the catalytic performance of platinum catalysts

• Uncover the effect of O-vacancies on the electrical conductivity of CaMnO3.
• SMSI is observed between Pt cluster and CaMnO3 compared with Pt5/graphene.
• SMSI in Pt5/CaMnO3 promote dissociation of O2 and the desorption of intermediates.

To explore the effect of strong metal/support interaction (SMSI) on the activity and stability of Pt/CaMnO3 catalyst for oxygen reduction reaction (ORR), we investigate the geometry and electronic structure of CaMnO3-supported Pt5 cluster system, as well as its reactive properties toward ORR using density functional theory. The results show that a moderate amount of O-vacancies obviously improve the electrical conductivity of CaMnO3 through narrowing its energy gap, which induces a lower electron transfer resistance of CaMnO3 particles themselves. When the Pt5 cluster is loaded on CaMnO3, a stronger interaction will form between the Pt5 cluster and CaMnO3 than that between Pt5 cluster and graphene, since more charge transfer from support to CaMnO3, and larger overlap between Op states of CaMnO3 and Ptd states of Pt5 cluster. In addition, for Pt5/CaMnO3, it can be found that charge transfer from catalyst to O2 promotes dissociation of O2, and lowering of d-band center of Pt5 facilitates desorption of intermediates when compared with Pt5/graphene.