Polarity driven morphology of CeO2(1 0 0) islands on Cu(1 1 1)

Abstract

Thin ceria films supported by metal substrates represent important model systems for reactivity studies in heterogeneous catalysis. Here we report the growth study of the polar CeO2(100) phase as part of a mixed CeO2(111)–CeO2(100) thin film supported by Cu(111). The two ceria phases grow on different areas of the substrate, what allows a reliable growth characterization of the CeO2(100) islands on Cu(111). Scanning tunneling microscopy measurements reveal CeO2(100) to grow in the form of highly dispersed three dimensional (3D) islands on a CeO2(100) interfacial layer. The CeO2(100) islands exhibit a 2×2 surface reconstruction. The presence of the surface reconstruction together with the highly dispersed growth of CeO2(100) islands corresponds to the requirement for compensation of the surface dipole moment on the CeO2(100). CeO2(100) islands are further characterized by reflection high energy electron diffraction yielding their epitaxial relations with respect to the Cu(111) substrate. The growth of well characterized CeO2(100) islands supported by Cu(111) represents a starting point for developing a novel template for structure-related reactivity studies of ceria based model catalysts.