Surface structure of nickel oxide layers on a Rh(111) surface

Abstract

The formation of nickel oxide nanolayers by oxidizing Ni overlayers on Rh(111) has been investigated and their structures are reported as a function of the nickel coverage and oxygen pressure. Scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and diffraction (XPD), and high-resolution electron energy loss spectroscopy (HREELS) have been applied to characterize the structure and stoichiometry of the nickel oxide nanolayers. Several different phases have been observed depending on the strain state of the metallic Ni overlayers. For the pseudomorphic Ni monolayer, two distinctly different oxide phases with (6 ×1)-Ni 5 O 5 and (2√3×2)-Ni 8 O 10 structures have been identified at oxygen-poor (p=5×10 −8 mbar) and oxygen-rich (p≥1×10 −6 mbar) conditions, respectively. Above one monolayer, where the Ni layers are relaxed, bulk-like NiO(100) films form at the O-rich conditions, whereas chemisorbed-type p(2 ×2)O\Ni(111) layers develop in the O-poor regime. X-ray photoelectron diffraction analysis has provided additional insight into the relaxation mechanism and the detailed atomic structure of the Ni-oxide nanolayers.

Intercalation of O2 and N2 in the Graphene/Ni Interfaces of Different Morphologies

“…The first one is very similar to the one presented in Fig. 1(c,d) with a faint moiré structure, whereas for the gr/NiO/Ir(111) patches the corrugation of graphene is much larger due to the formation of the lattice-mismatched NiO/Ir(111) interface which demonstrates the long-range periodicities similar to the one observed for other NiO,CoO/4d,5d-metal(111) interfaces [38][39][40][41]. After intercalation of oxygen in gr/n ML-Ni/Ir(111) with thicker Ni layer of more than 1 ML, the STM images demonstrate stripelike and maze-like long-range ordered structures for the NiO layer under graphene, which is also supported by fast Fourier transformation (FFT) images ( Fig.…”

Key role of rotated domains in oxygen intercalation at graphene on Ni(1 1 1)

“…The component O 1 is compatible both with chemisorbed oxygen on Ni(111) and with the formation of NiO [47][48][49][50][51][52][53]. The component O 2 can be attributed either to the presence of regions of non-stoichiometric NiO rich in Ni 3+ groups [47][48][49][50][51][52] or to oxygen belonging to the top layer of NiO [49,54].…”

Growth from behind: Intercalation-growth of two-dimensional FeO moiré structure underneath of metal-supported graphene

“…The growth of 2D oxides by intercalation may not be limited to FeO. A large number of 2D-oxide monolayers on late transition metal substrates have been explored over the last decade 60 61 62 63 64 65 66 67 68 69 70 . These are the same transition metal substrates that support CVD growth of graphene 8 and thus may allow combining oxide monolayers with graphene.…”