TY - GEN A1 - Flege, Jan Ingo A1 - Höcker, Jan A1 - Sadowski, Jerzy T. A1 - Senanayake, Sanjaya D. A1 - Falta, Jens T1 - Nucleation, morphology, and structure of sub‐nm thin ceria islands on Rh(111) T2 - Surface and Interface Analysis N2 - The early stages of ceria growth on Rh(111) at high temperature have been investi-gated by low‐energy electron microscopy and photoemission electron microscopy. Ceria was deposited by reactive Ce deposition at substrate temperatures between 700°C and 900°C in an oxygen ambient of 5 × 10−7 Torr. At 700°C, we observe a high nucleation density of 100‐nm‐sized islands. With elevated temperature, the average island size increases, and the nucleation density decreases. Triangularly shaped islands nucleate preferentially at step edges, with seemingly abrupt interfaces between Ce and Rh. At 900°C, the island edges are still straight, but during growth the islands lose their triangular form. Instead, growth along the substrate step edges becomes favorable, leading to a maze‐like morphology. Atomic force microscopy reveals islands of 0.3 to 0.6‐nm height, consistent with ceria islands formed by one or two trilayers (O―Ce―O) of ceria. Moreover, the second layer of the islands is also triangularly shaped, with lateral dimensions of 50 nm and similar step heights. IV‐LEEM analysis leads to the conclusion that the rhodium surface is covered by a layer of reduced cerium oxide, which is partially overgrown by smaller islands of CeO2. KW - ceria KW - Rh (111) KW - low‐energy electron microscopy (LEEM) KW - photoemission electron microscopy (PEEM) KW - IV-LEEM Y1 - 2019 U6 - https://doi.org/10.1002/sia.6567 SN - 0142-2421 SN - 1096-9918 VL - 51 IS - 1 SP - 110 EP - 114 ER - TY - GEN A1 - Tschammer, Rudi A1 - Buß, Lars A1 - Morales, Carlos A1 - Senanayake, Sanjaya D. A1 - Falta, Jens A1 - Flege, Jan Ingo T1 - In situ characterization of cerium oxide on Au(111) under reducing and oxidizing conditions by low-energy electron microscopy T2 - Verhandlungen der DPG N2 - The development of novel catalysts for a variety of applications is a key challenge for modern catalysis. Inverse metal oxide catalysts consisting of oxide nanoparticles dispersed on a metal support have recently attracted much attention, showing higher activity and selectivity compared to traditional catalytic systems, harnessing synergistic effects attributed to the so-called metal-support interaction. To gain further insights, we deposited cerium oxide nanoparticles on Au(111) and studied this system by low-energy electron microscopy (LEEM) and low-energy electron diffraction (LEED). The prepared samples demonstrate a distinct correlation between the deposition temperature and the structural order of the nanoparticles. This has been expanded upon by exploring the changes induced by reduction with H2 and reoxidation with O2 or CO2, again exhibiting a connection between structural order and activity, while also showing the influence of the oxide-metal interaction on the stability of cerium oxide under reducing conditions. KW - low-energy electron microscopy KW - cerium oxide KW - reduction KW - reoxidation KW - low-energy electron diffraction (LEED) Y1 - 2023 UR - https://www.dpg-verhandlungen.de/year/2023/conference/skm/part/o/session/78/contribution/9 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Tschammer, Rudi A1 - Buß, Lars A1 - Pożarowska, Emilia A1 - Morales, Carlos A1 - Senanayake, Sanjaya D. A1 - Prieto, Mauricio J. A1 - Tănase, Liviu C. A1 - de Souza Caldas, Lucas A1 - Tiwari, Aarti A1 - Schmidt, Thomas A1 - Niño, Miguel A. A1 - Foerster, Michael A1 - Falta, Jens A1 - Flege, Jan Ingo T1 - High-temperature growth of CeOx on Au(111) and behavior under reducing and oxidizing conditions T2 - The journal of physical chemistry C N2 - Inverse oxide–metal model catalysts can show superior activity and selectivity compared with the traditional supported metal–oxide architecture, commonly attributed to the synergistic overlayer–support interaction. We have investigated the growth and redox properties of ceria nanoislands grown on Au(111) between 700 and 890 °C, which yields the CeO2–Au(111) model catalyst system. We have observed a distinct correlation between deposition temperature, structural order, and oxide composition through low-energy electron microscopy, low-energy electron diffraction, intensity–voltage curves, and X-ray absorption spectroscopy. Improved structural order and thermal stability of the oxide have been achieved by increasing the oxygen chemical potential at the substrate surface using reactive oxygen (O/O2) instead of molecular O2 during growth. In situ characterization under reducing (H2) and oxidizing atmospheres (O2, CO2) indicates an irreversible loss of structural order and redox activity at high reduction temperatures, while moderate temperatures result in partial decomposition of the ceria nanoislands (Ce3+/Ce4+) to metallic cerium (Ce0). The weak interaction between Au(111) and CeOx would facilitate its reduction to the Ce0 metallic state, especially considering the comparatively strong interaction between Ce0 and Au0. Besides, the higher reactivity of atomic oxygen promotes a stronger interaction between the gold and oxide islands during the nucleation process, explaining the improved stability. Thus, we propose that by driving the nucleation and growth of the ceria/Au system in a highly oxidizing regime, novel chemical properties can be obtained. KW - Inverse oxide-metal model catalysts KW - Ceria nanoislands KW - Growth KW - Redox properties KW - Low-energy electron microscopy (LEEM) KW - Low-energy electron diffraction (LEED) KW - Intensity–voltage curves KW - X-ray absorption spectroscopy (XAS) Y1 - 2025 U6 - https://doi.org/10.1021/acs.jpcc.4c08072 SN - 1932-7447 VL - 129 IS - 7 SP - 3583 EP - 3594 PB - American Chemical Society (ACS) CY - Washington, DC ER -