Single Gold Atom Adsorption on the Fe₃O₄(111) Surface

For understanding the catalytic activity of Fe₃O₄-supported gold catalysts, the adsorption structures and energies of a single Au atom on the six terminations of the Fe₃O₄(111) surface have been computed at the level of density functional theory (GGA+<i>U</i>). For the most stable adsorption configurations, correlation has been found between the surface stability and the Au atom adsorption energy; that is, the more stable the surface, the lower the Au atom adsorption energy. It is also found that the adsorbed Au atom is reduced and has a negative charge on the iron-terminated surfaces, whereas it is oxidized and has a positive charge on the oxygen-terminated surfaces, and the latter is in agreement with the experimental observation. No correlation between the transferred charge and the adsorption energy has been found. Regarding the experimentally observed oxidation of gold nanoparticles on the iron oxide surface, it is possible to produce an oxygen-terminated surface for gold adsorption by synthetic tuning