Role of Surface Hydroxyl Groups on Zinc Adsorption Characteristics on α-Al₂O₃(0001) Surfaces: First-Principles Study

Abstract

Adhesion at zinc/alumina interface is a key issue in the field of steelmaking industry, where selective Al oxidation, followed by surface segregation of alumina islands, efficiently impedes wetting of anticorrosive Zn coating on the high strength steel grades. Relying on ab initio total energy calculations, we have examined adsorption of Zn adatoms on different terminations of α-Al2O3(0001) surface under both vacuum conditions and in the presence of surface hydroxyls. Surface configurations with strongly bound Zn and thermodynamic conditions necessary for their stability have been identified. We have shown the existence of a wide range of nonextreme oxygen-rich conditions under which Zn tends to spill over the alumina substrate as an array of strongly adsorbed adatoms, rather than to form metallic clusters weakly bound to the substrate. This effect has been assigned to surface non-neutrality, such as due to surface polarity, or to an excess of surface hydroxyls. Moreover, compared to its direct neighbors in the periodic table (Cu, Ag), we have shown that surface structures with strongly bound adatoms can be stabilized already in much more oxygen-poor conditions.

Effects of surface hydroxylation on adhesion at zinc/silica interfaces

“…This comparison reveals a thermodynamic bias for an exchange between surface hydrogen and zinc atoms present under a wide span of oxygen-moderate and -rich environments. We recall that a similar trend has already been reported for Zn adsorbates at the hydroxylated α-alumina terminations, 32 for which the activated character of the hydrogen-zinc exchange has been explicitly demonstrated by both experiment and first principles calculations. 27 More importantly, all H-lean interface configurations present in the stability diagram Fig.…”

“…Surface pre-hydroxylation may be a promising way to achieve this. Moreover, it has been shown that reaction of metal adatoms with surface OH groups on prehydroxylated alumina results in a formation of strongly bound oxidized species, [28][29][30][31][32] and leads to a substantial improvement of zinc adhesion. 33 .…”

Structural, electronic and adhesion characteristics of zinc/silica interfaces: ab initio study on zinc/β-cristobalite

“…An assessment of zinc/silica interactions under different thermodya CNRS, Institut des Nanosciences de Paris, UMR 7588, F-75005 Paris, France. Fax: ; +33 (0)1 44 27 39 82 Tel: +33 (0)1 44 27 46 17; E-mail: Jacek. Goniakowski@insp namic conditions will help to obtain a more precise understanding of the microscopic mechanisms responsible for the interfacial strength and to define appropriate process parameters promoting the adhesion of zinc coating on Si alloyed grades.…”

Ligand‐Free, Highly Dispersed NiOx Nanocrystal for Efficient, Stable, Low‐Temperature Processable Perovskite Solar Cells

“…These water molecules then lead to the gradual decomposition of MAPbI 3 into MAI and PbI 2 . In addition, hydroxyl groups decompose the perovskite into PbI 2 , CH 3 NH 2 , I, and H 2 O . The generated water would further accelerate the decomposition process.…”

“…[42,43] In addition, hydroxyl groups decompose the perovskite into PbI 2 , CH 3 NH 2 , I, and H 2 O. [44,45] The generated water would further accelerate the decomposition process. Equations (1) and (2) show possible degradation reactions for W-NiO x [40,46] :…”