In situ chemical and morphological characterization of copper under near ambient reduction and oxidation conditions

By using spatially resolved photoelectron spectromicroscopy, we have investigated the formation of Cu(I) oxide phases when a bulk Cu foil is exposed to a near ambient pressure of molecular oxygen. The experiment was performed by using a novel cell for in operando measurements capable to overcome the so called ‘pressure gap’. We have found that the oxidation of Cu proceeds through the formation of Cu(I) oxide domains in the micron and submicron range size, the evolution of which affects the overall morphology of the Cu surface as well. Chemical and morphological changes have been simultaneously detected. It was, surprisingly, found that during the oxidation process in many areas domains having +1 valence state do not spread on the metallic regions which homogenously oxidize; no chemical oxidizing wave was detected by the available lateral resolution and time frame.