DFT Investigation of X55 (X = Ni, Pd, and Pt) Clusters on Ultrathin Supported MgO Films: Evidence of Oxygen Spillover and Relevance for Catalytic Model Studies

The adsorption of X55 (X = Ni, Pd, and Pt) nanoclusters is simulated by using first-principles methods on MgO(100) and on a MgO monolayer supported on Ag(100), considering the presence of interfacial oxygen. On both the free-standing MgO surface and MgO/Ag, all clusters exhibit robust adhesion and negative charge transfer. Ab initio molecular dynamics calculations at 200 K demonstrate the stability of the X55 nanoparticles on the MgO/Ag support. The presence of oxygen segregated at the MgO-Ag interface significantly stabilizes the adsorbed X55 clusters, particularly Ni55, and induces electron withdrawal. Thermodynamically favorable reverse oxygen spillover from the interface to the adsorbed particles occurs for Ni, Pd, and Pt, altering the particles’ charge polarity. Simulation of higher oxygen loading at the surface results in spontaneous spillover, with some oxygen atoms segregating back at the MgO/Ag interface, which can thus act as a buffer during oxidation processes on the metal nanoparticles. Our computational results, which provide detailed insights into the adsorption of X55 nanoclusters on various supports, efficiently present a wide range of scenarios and hypotheses, serving as realistic models for experimental studies.