Diverse reactivity patterns observed in the interaction of oxygen with nickel deposited on gold and tungsten surfaces

Abstract

Interaction of oxygen with nickel overlayers on gold and tungsten surfaces has been investigated by employing core-level spectroscopy. The Ni₂p_3/2 binding energy at a monolayer coverage of nickel (θNi ∼1 ML) is significantly differ compared to that at high coverages or of the bulk nickel. The Ni/Au surface showing a large negative shift in the binding energy (ΔE_c ∼ −0.5 eV) adsorbs oxygen on a prolonged exposure and gives rise to a high proportion of the O¹⁻ species. In contrast, the Ni/W surface with ΔE_c ∼ +0.3 eV reacts vigorously on exposure to oxygen, the O²⁻ species being predominant on the surface. Charge transfer across the Ni/Au(W) interface is suggested to be responsible for the observed diverse reactivity patterns with oxygen. Bimetallic surfaces formed by depositing palladium on silver and tungsten surfaces also exhibit a similar behaviour.