Structural Transformation of Supported, Intercalated, and Doped Cu Nanostructures on FeO/Pt(111) under Oxidizing and Reducing Conditions

The structural evolution of supported metal catalysts often happens during reaction and can strongly influence their catalytic performance. Thus, understanding the structural transformation of metal catalysts under different conditions is critical to modulating their activity and stability. Here, Cu nanostructures on monolayer FeO film on Pt(111) have been constructed, which are used as model systems to study the structural changes of Cu under different treatment conditions by using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Supported Cu nanostructures on FeO (Cu/FeO/Pt(111)) can be prepared by deposition of Cu at 100 K, and they can transform into intercalated Cu structures (FeO/Cu/Pt(111)) by annealing at 300 K in ultrahigh vacuum and further change to PtCu alloy (FeO/Pt/PtCu) at 700 K. Annealing the supported and intercalated Cu structures in O2 atmosphere induces the formation of Cu dopants in the FeO film (Cu x Fe y O z /Pt­(111)). Furthermore, intercalated and doped Cu nanostructures can be reversibly transformed into each other under redox treatments. The atomic identification of Cu structural evolution and the coordination environments of Cu dopants provide a deep understanding of Cu catalysts under reaction conditions.