A monolayer of Pd on ZrC(0 0 1) speeds up O2 dissociation: An ab initio study

Abstract

We propose the Pd monolayer (ML) on ZrC(001) surface as an effective catalyst for the dissociation of oxygen by density functional theory calculations. We find that the coverage of Pd has a conspicuous impact on the adsorption and dissociation of O2. The strong interaction between the Pd atoms and the ZrC(001) support enhances the reactivity and stability of the electrocatalyst. By comparing the binding energies of Pd-Pd and Pd-C, we conclude that the Pd adatoms do not aggregate to form a cluster and prefer to form a monolayer when the coverage is low. With a monolayer of coverage, the C sites are fully saturated by adsorbed Pd atoms, which prevent the oxidation of the ZrC(001) surface. The dissociation activity of O2 on PdML/ZrC(001) is predicted to be a rival of or even surpass Pt(111). In addition, the high mobility of the dissociated oxygen atoms on PdML/ZrC(001) also benefits the later reaction step for ORR.