Stability and activity of PdCu clusters embedded on pyridinic N-doped graphene: a density functional theory investigation

Abstract

The stability and reactivity of Pd_6-nCu_n (n = 0−3) clusters supported on pyridinic N-doped graphene (PNG) were investigated using the auxiliary density functional theory method. First, the stability of Pd_6-nCu_n (n = 0−3) clusters supported on PNG was analyzed using charge transfer, interaction energy, and electron density critical point calculations. Then, the reactivity of these clusters supported on PNG was computed using frontier molecular orbitals and oxygen adsorption energies. According to the calculated interaction energy, as the Cu content increased, the interaction energy between Pd_6-nCu_n (n = 0−3) clusters and PNG increased. The charge transfer indicated that the clusters donate charge to the PNG. Based on the energy of the frontier orbitals, the Pd₅Cu cluster supported on PNG exhibits the smallest HOMO–LUMO gap inferring that this system is the most reactive, whereas the less reactive system corresponds to the Pd₄Cu₂ cluster supported on PNG. Finally, the oxygen adsorption energies on Pd₆ (−3.86 eV) and Pd₅Cu (−3.87 eV) clusters supported on PNG were similar. However, the Pd₅Cu cluster has a lower Pd content than the Pd₆ cluster. Therefore, this work reveals that PdCu systems supported on PNG could be cheap and efficient catalysts for the oxygen reduction reaction.

GRAPHICAL ABSTRACT

Keywords:

• HOMO–LUMO gap
• Charge transfer
• Critical points
• Oxygen adsorption energy

Acknowledgements

L. López-Sosa acknowledges CONACYT for his postdoctoral fellowship.

Disclosure statement

No potential conflict of interest was reported by the author(s).