Selective studies of adsorption of Ag₈M and Ag₁₄M clusters (M = Au, Co and Pt) on alumina substrate

Small silver clusters were used as catalyst for Li-air batteries, which controlled the rate of discharge at the cathode. The gap near the fermi energy was shown to control the oxygen reduction, an important reaction for LiO₂ formation. One can vary the size of the cluster to vary the gap, however, this “knob” provides limited variance. Hence, we study the effect of alloying in combination with size variation of Ag₈M and Ag₁₄M clusters (M = Au, Co and Pt). Using Density Functional Theory (DFT), we determine the most stable geometry of these bimetallic clusters and calculate the binding energies of these clusters on the alumina substrate. We explore how the gap at the Fermi level of the system varies as a function of elemental composition and size of the cluster. Bader charge analysis is also performed to probe how the charges are transferred between the cluster and the substrate. These preliminary studies will open the door for more systematic studies of alloy clusters of different size and stoichiometry for Li-O₂ battery cathode design as well as for general catalysis.