First principles study on the oxygen reduction reaction of Ir@Pt core-shell structure

The core-shell nanostructure can combine the properties of the core and the shell, thereby improving the performance of the oxygen reduction reaction (ORR) catalyst. The Ir@Pt core-shell nanostructure (CSNS) is considered to be a potential ORR catalyst due to its properties both of Ir and Pt. In this paper, a complete series of Ir@Pt core-shell nanostructure with different exposure surfaces and monolayers (ML) of Pt shell are designed and scrutinized for ORR activity. The results show that the Ir@Pt CSNSs can effectively reduce the binding energy of all intermediates, and most CSNSs can reduce the overpotential of ORR. At the same time, the formation of CSNS will strengthen the association mechanism but weaken the dissociation mechanism. It is worth noting that the reduction in binding energy can not simply be the same as the reduction in overpotential. The strain effect and the electronic effect act on the change of the overpotential at the same time. However, the electronic effect plays the main role in the overpotential change caused by the change of the number of layers. The analysis of the deformed charge density and charge transfer shows that the electronic effect is only effective within 2ML, the reason for the decrease in binding energy is that a part of electrons in the Ir core transfer to the surface and combine with the intermediates. Among all CSNSs, Ir@Pt 1ML and 2ML have significantly reduced the overpotential of ORR, which indicates that Ir@Pt is a potential ORR catalyst.

Automated summary

The Ir@Pt core-shell nanostructure shows potential as an ORR catalyst, effectively reducing the binding energy of intermediates and overpotential of ORR. The electronic effect plays a major role in the performance change of Ir@Pt CSNS, especially within 2ML of Pt shell layers, where electron transfer and combination with intermediates occur.