Formation of H₂O₂ on Au₂₀ and Au₁₉Pd Clusters: Understanding the Structure Effect on the Atomic Level

Supported gold nanoparticles are promising catalysts for production of H₂O₂ from O₂ and H₂. Size, structure, and palladium doping effects play the key role in activity and selectivity of a gold catalyst. We performed a study of the influence of Au₂₀ and Au₁₉Pd structure features on the main steps of H₂O₂ formation on the atomic level, using the DFT/PBE approach with relativistic all electron basis set. The top, edge, and facet atoms of the tetrahedral Au₂₀ cluster as well as a palladium atom of Au₁₉Pd located on the top, edge, and facet of a tetrahedron have been considered as active sites of steps involved in H₂O₂ synthesis. The thermodynamic and kinetic data including Gibbs free energies and the activation Gibbs free energies were calculated for the steps determining the formation of H₂O₂ (H_(s) + OOH_(s) = H₂O_2(s), H₂O_2(s) = H₂O_2(g)) and for one step decreasing the selectivity (H₂O_2(s) = OH_(s) + OH_(s)). Gold tends to have low activity and high selectivity in H₂O₂ synthesis regardless of the structure of active site. Low coordinated palladium atoms promote H₂O₂ formation as well as its dissociation. Pd on a facet of a cluster facilitates H₂O₂ production with high activity and selectivity.