Theoretical study of PdNi and PdCu clusters embedded on graphene modified by monovacancy and nitrogen doping

The stability and reactivity of Pd₄Ni₄ and Pd₄Cu₄ clusters embedded on graphene modified by monovacancy and nitrogen doping were investigated using auxiliary density functional theory (ADFT) calculations. The most stable structure of the Pd₄Ni₄ cluster is found in high spin multiplicity, whereas the lowest stable energy structure of the Pd₄Cu₄ cluster is a close shell system. The interaction energies between the bimetallic clusters and the defective graphene systems are significantly higher than those reported in the literature for the Pd-based clusters deposited on pristine graphene. It is observed that the composites studied present a HOMO-LUMO gap less than 1 eV, which suggests that they may present a good chemical reactivity. Therefore, from the results obtained in this work it can be inferred that the single vacancy graphene and pyridinic N-doped graphene are potentially good support materials for Pd-based clusters.