Structures and catalytic properties of PdmAun (m+n=7) bimetallic clusters supported on graphene by first-principles studies

The geometrical structures and catalytic properties of PdmAun (m+n=7) bimetallic clusters supported on perfect graphene are systematically investigated by first-principles calculations and nudged-elastic-band simulations. The lowest energy structure of bimetallic PdmAun cluster trends to form a bilayer configuration. The anchor atoms of the most stable bimetallic clusters adsorbed on graphene are less than four Pd atoms. The stability of Au-based clusters is significantly enhanced by Pd atoms, and the bimetallic clusters of Pd3Au4 and Pd4Au3 show high stability on graphene. Moreover, on Pd2Au5 and Pd3Au4, CO can directly react with the adsorbed O2 with a low barrier of ∼0.20 eV to form an intermediate metastable state (OOCO), and it is easily dissociated into a CO2 and a residual O after crossing a relatively low energy barrier. We indeed suggest the Pd atoms can simultaneously enhance the stability and catalytic reactivity of graphene-supported Au-based nanoclusters.