According to recent theoretical and experimental studies, the formation of bulk or surface oxide phases on transition metals is a common phenomenon under real catalysis conditions. The identification of the actual active phase during catalytic oxidation reactions is therefore a key issue in understanding their reactivity.
We have studied the oxidation of the Rh(110) surface by Scanning Tunneling Microscopy: while a flat trilayer surface oxide forms after HP O2 or UHV atomic-O exposure of the clean surface, a more and more rough oxidized surface results from repeated oxidation/annealing cycles. The increasing roughness is related to the incorporation of oxygen in the sub-surface region and in the bulk, and might be due to the formation of bulk-oxide nano-particles.
Finally, preliminary results on the reactivity at the different oxidation stages will be presented. |