Hydrogen Production on Aluminum in Alkaline Media
S.M. Abd El Haleem, S. Abd El Wanees, A. Farouk
Abstract
Abstract The corrosion behavior and hydrogen generation on aluminum in NaOH solutions are followed up using different techniques. The rates of Al2O3 film destruction, metal dissolution, and hydrogen gas production are dependent on the alkali amount and the solution temperature. The existence of two capacitive semicircles at high and low frequencies confirm the charge transfer process on the metal surface. The existence of an inductive loop at intermediate frequencies emphasizes the surface charge due to the building up of oxide film at the Al/Al2O3 interface. Low values of free energy of activation of these processes Ea indicate that these processes are controlled by a diffusion step. The positive values of ΔHa reflect the endothermic nature of the activation processes, while the negative values of ΔSa indicate a decreased disordering of a dissociation step.