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O: Fachverband Oberflächenphysik
O 7: Heterogeneous Catalysis: Experiment
O 7.9: Talk
Monday, March 12, 2018, 12:30–12:45, MA 141
Scanning tunneling microscopy study of the structure and interaction between carbon monoxide and hydrogen on the Ru(0001) surface — •Barbara A J Lechner1,2, Xiaofeng Feng1, Peter J Feibelman3, Jorge I Cerdá4, and Miquel Salmeron1 — 1Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA — 2Department of Chemistry & Catalysis Research Center, Technical University of Munich, Germany — 3Sandia National Laboratories, Albuquerque, NM, USA — 4Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, 28049 Madrid, Spain
As the earth's crude oil supply dwindles, the Fischer-Tropsch process to create hydrocarbon fuels from two abundant resources, carbon monoxide and hydrogen, gains in significance. Here, we use scanning tunneling microscopy (STM) to investigate the spatial arrangement of CO and H coadsorbed on a model catalyst surface, Ru(0001). We find that at cryogenic temperatures, CO forms small triangular islands of up to 21 molecules with hydrogen segregated outside of the islands. Furthermore, whereas for small island sizes (3-6 CO molecules) the molecules adsorb at hcp sites, a registry shift toward top sites occurs for larger islands (10-21 CO molecules). To characterize the CO structures better and to help interpret the data, we carried out density functional theory (DFT) calculations of the structure and simulations of the STM images, which reveal a delicate interplay between the repulsions of the different species.