Formation of cobalt oxide clusters on oxygen modified graphene

Abstract: Aim of this thesis is to study and characterize the formation of cobalt oxide clusters on graphene. The performed experiments consist of three different steps. First, a monolayer graphene film is grown with temperature programmed growth and chemical vapor deposition on an Iridium (111) single crystal surface. Second, the graphene film is exposed to oxygen radicals, which bind to the film and form clusters. In the last step, cobalt oxide was deposited onto the O-functionalized graphene film to form cobalt oxide clusters atop the oxygen clusters.\\ The evolution of the experiment is studied with x-ray photoelectron spectroscopy. The recorded data of the C 1s spectrum from the O-functionalization experiment are coherent with recently published literature on the same topic. The Ir 4f$_{7/2}$ suggests that 6.5\% of the carbon atoms are bound in an epoxy group. Furthermore the Ir 4f$_{7/2}$ spectra show exclude intercalataion of oxygen or cobalt oxide. Subsequent deposition of cobalt oxide on the O-functionalized graphene film leads to cobalt oxide in rocksalt structure containing Co$^{2+}$ ions. The ratio of cobalt oxide and the epoxy group is 1:1 which suggest the formation of cobalt oxide cluster onto the oxygen radicals. Nonetheless, further scanning tunneling microscopy experiments have to be performed to describe the stability, structure, size and coverage of these clusters. This is briefly discussed in the outlook.