Cluster–support interaction in Au–Fe3O4 system

Cluster–support interaction in a Au–Fe3O4(0 0 1) system was studied using scanning tunneling microscopy, X-ray photoemission spectroscopy and Mössbauer spectroscopy, in situ, under ultra high vacuum conditions. Deposition of 0.02–5 monolayers of Au resulted in the growth of two- and three-dimensional gold nano-cluster. The positive shift of the Au 4f7/2 electron binding energy for the smallest clusters was correlated with modification of the electronic structure in the surface magnetite layer, as found from Mössbauer analysis, leading to conclusion that a positive charging of small Au clusters can be responsible for their outstanding catalytic activity.