RESUMO
Correction for 'Insight at the atomic scale of corrosion inhibition: DFT study of 8-hydroxyquinoline on oxidized aluminum surfaces' by Fatah Chiter et al., Phys. Chem. Chem. Phys., 2023, https://doi.org/10.1039/d2cp04626a.
RESUMO
8-Hydroxyquinoline (8-HQ) is a promising organic molecule for the corrosion protection of aluminum and its alloys in the replacement of chromate salts. On the aluminum surface, the presence of an oxide layer naturally formed can influence the inhibition efficiency which depends on molecule-surface interactions. In the present study, we performed quantum chemical calculations on native 8-HQ, tautomer and 8-Q (deprotonated, H-abstracted or radical) molecules, adsorbed on an oxidized aluminum surface (γ-Al2O3(111)/Al(111)). All species have the ability to interact strongly with the oxidized aluminum surface and can form stable and dense organic films. The bonding strength of different species of 8-HQ on oxidized aluminum surfaces is more favorable for 8-Q and tautomer species than for the native 8-HQ molecule. On the surface, the native 8-HQ molecule is physisorbed, forming H-bonds, in contrast to the tautomer and 8-Q species that show the predominance of chemisorption modes, involving both H-bonds and covalent bonds at the molecule/substrate interface. The dispersion energy significantly contributes to the adsorption mechanism and increases with increasing molecular surface coverage, due to attractive molecule-molecule interactions. Regardless of surface coverage and considered reaction mechanisms, the 8-Q species is able to enhance the stability of all aluminum sites, and thus to slow down the anodic reaction. In contrast, the native molecule and the tautomeric form have no significant effect or even weakened the stability of aluminum surface atoms.
RESUMO
8-Hydroxyquinoline (8HQ) is a new green corrosion inhibitor. DFT-D calculations are performed to investigate the adsorption of 8HQ and derivatives on the Al(111) surface from low to high coverage. From θ = 0.20 to 0.66, the adsorption energies are -1.12, -2.41, -1.66 and -3.44 eV per molecule for 8HQ, and its tautomer, its hydrogenated and its dehydrogenated species, independently of the coverage. In contrast, the geometry of the adsorbates changes between coverage up to 0.66 and the full monolayer (θ = 1). The creation of a dipole at the molecule/metal interface reduces the work function of aluminum. To further evaluate the modification of the reactivity of the surface, adsorption of O2 on the Al(111) surface covered by the organic layer is investigated. O2 dissociation takes place for θ = 0.66. When the Al surface is fully covered (θ = 1), the reduction of O2 and the oxidation of Al atoms do not occur.
RESUMO
The 8-hydroxyquinoline (8-HQ) molecule is an efficient corrosion inhibitor for aluminum and is also used in organic electronic devices. In this paper, the adsorption modes of 8-HQ and its derivatives (tautomer, dehydrogenated and hydrogenated species) on the Al(111) surface are characterized using dispersion corrected density functional theory calculations. The 8-HQ molecule is physisorbed and is chemisorbed on the aluminum surface with similar adsorption energy (-0.86 eV to -1.11 eV) and these adsorption modes are stabilized by vdW interactions. The binding of the dehydrogenated species is the strongest one (adsorption energy of -3.27 eV to -3.45 eV), followed by the tautomer molecule (-2.16 eV to -2.39 eV) and the hydrogenated molecule (-1.71 eV) that bind weaker. In all the chemisorbed configurations there is a strong electronic transfer from the Al substrate to the adsorbate (0.72 e to 2.16 e). The adsorbate is strongly distorted and its deformation energy is high (0.55 eV to 2.77 eV). The analysis of the projected density of states onto the orbitals of the molecule and the electronic density variation upon adsorption (Δρ) between the molecule and the surface account for covalent bonding.
