Corrosion protection of Al(111) by 8-hydroxyquinoline: a comprehensive DFT study

Abstract

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.