Publications in Scientific Journals:

P. Ferstl, F. Mittendorfer, J. Redinger, M. Schneider, L. Hammer:
"Monoatomic Co, CoO2, and CoO3 nanowires on Ir(100) and Pt(100) surfaces";
Physical Review B, 96 (2017), 08540701 - 08540712.

English abstract:
In this study, we investigate the structural and chemical changes of monatomic CoO2 chains grown selforganized
on the Ir(100) surface [P. Ferstl et al., Phys. Rev. Lett. 117, 046101 (2016)] and on Pt(100) under
reducing and oxidizing conditions. By a combination of quantitative low-energy electron diffraction, scanning
tunneling microscopy, and density functional theory we show that the cobalt oxide wires are completely reduced
by H2 at temperatures above 320 K and a 3 1 ordered Ir2Co or Pt2Co surface alloy is formed. Depending
on temperature, the surface alloy on Ir(100) is either hydrogen covered (T < 400 K) or clean and eventually
undergoes an irreversible order-disorder transition at about 570 K. The Pt2Co surface alloy disorders with the
desorption of hydrogen, whereby Co submerges into subsurface sites. Vice versa, applying stronger oxidants
than O2 such as NO2 leads to the formation of CoO3 chains on Ir(100) in a 3 1 superstructure. On Pt(100),
such a CoO3 phase could not be prepared so far, which, however, is due to the ultrahigh vacuum conditions of
our experiments. As revealed by theory, this phase will become stable in a regime of higher pressure. In general,
the structures can be reversibly switched on both surfaces using the respective agents O2, NO2, and H2.

Created from the Publication Database of the Vienna University of Technology.