Experimental and Theoretical Study of a Surface Stabilized Monolayer Phase of Nickel Oxide on Pd(100)

Abstract

A surface stabilized monolayer phase of nickel oxide, c(4 x 2)-Ni(3)O(4), has been found to grow epitaxially under reactive deposition conditions on Pd(100), in the presence of other adsorbed phases and in competition with them. High-quality scanning tunneling microscopy data are reported and discussed, including a detailed analysis of the defects and of the border morphology of this new phase. The data are discussed in the light of ab initio simulations of the electronic, energetic, and geometric properties of such a phase. A hybrid-exchange density functional theory approach has been used, and a slab model is adopted where palladium is simulated by a thin film covered on both sides by regular epilayers. A growth model has been developed that explains both the unusual stoichiometry of the phase and the observed defects.

Synergetic Effect of Surface and Subsurface Ni Species at Pt−Ni Bimetallic Catalysts for CO Oxidation

“…More importantly, the oxide nanostructures have monolayer thickness (Figure S1b), similar to NiO nanostructures grown on Pt(111) 66 and Pd(100). 67 It should be noted that, under the same deposition conditions, 3D NiO islands were obtained on the HOPG surface ( Figure S4). Therefore, it can be concluded that the interface confinement effect between oxide overlayers and metal substrates also plays a critical role in stabilization of the 2D NiO nanoislands.…”

Interplay between structural, magnetic, and electronic properties in aFeO∕Pt(111)ultrathin film

“…[1][2][3][4] Films of a few atomic layers may exhibit structures that are completely different from those of bulk oxides and display many different phases, depending on the growth conditions. [5][6][7][8] In some cases, even though the structural and electronic properties of the ultra-thin films are similar to those of the massive material, the films may indeed display unexpected properties. For instance, it has been shown that MgO thin films on Mo(100) or Ag(100) substrates may exhibit modified reactivity towards adsorbed molecules or metals.…”

Silver nanostructures on a c(4×2)-NiOx/Pd(100) monolayer

“…Under these conditions a flat continuous layer of c(4 · 2)-NiO x is formed with very few vacancy islands. For a detailed description of this surface we refer to our previous work [34][35][36][37].…”

“…We have reported previously the structure and morphology of NiO/Pd(1 0 0) ultrathin films, with particular attention towards novel structures and properties stemming from the large lattice mismatch [33][34][35][36][37]. In the monolayer (ML) coverage range a new defective NiO x c(4 · 2) structure (x = 1.33) has been thoroughly investigated by both static and dynamic low energy electron diffraction (LEED) [36], STM [37], and photoemission spectroscopy (both valence and core levels) [38].…”

“…In the monolayer (ML) coverage range a new defective NiO x c(4 · 2) structure (x = 1.33) has been thoroughly investigated by both static and dynamic low energy electron diffraction (LEED) [36], STM [37], and photoemission spectroscopy (both valence and core levels) [38]. In the following we present a morphological and chemical characterization of the Ag/ NiO x /Pd(1 0 0) system, prepared by Ag UHV evaporation on the c(4 · 2) NiO x /Pd(1 0 0) ML film, for different Ag coverages.…”