The Effects of Acid and Water in the Formation of Anodic Alumina: DFT and Experiment Study

The DFT method is employed to study the adsorption and reaction behaviors of HC2O4-, H2PO4-, HSO4- and H2O on neutral and anodic aluminum slabs. With the exception of adsorption, the three acid radicals can successively take the two H atoms from the adsorbed H2O on the anodic aluminum slabs, which is the key step of the formation of anodic alumina. The dehydrogenation reaction is dominated by the Coulombic interaction of O and H, respectively belonging to acid radicals and the adsorbed H2O or OH, rather than by the interaction of electronic orbits located on the two kinds of atoms. The experiment of anodic polarization of aluminum verifies the calculation result well.

Automated summary

The DFT method is used to investigate the adsorption and reaction behaviors of HC2O4-, H2PO4-, HSO4-, and H2O on neutral and anodic aluminum slabs. The key step in the formation of anodic alumina is the successive extraction of two H atoms from adsorbed H2O on the anodic aluminum slabs by the three acid radicals. The dehydrogenation reaction is primarily governed by the Coulombic interaction between O and H, which belong to acid radicals and the adsorbed H2O or OH, respectively, rather than by the interaction of electronic orbits located on the two types of atoms. The experimental results of anodic polarization of aluminum confirm the calculated results well.