Hydrogen Production on Aluminum in Alkaline Media

• Published in: Protection of metals and physical chemistry of surfaces 2021-09, Vol.57 (5), p.906-916
• Main Authors: Abd El Haleem, S. M., El Wanees, S. Abd, Farouk, A.
• Format: Article
• Language: English
• Subjects: Activation energy; Aluminum; Aluminum oxide; Characterization and Evaluation of Materials; Charge transfer; Chemistry and Materials Science; Corrosion and Coatings; Corrosion products; Free energy; Hydrogen production; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Materials Science; Metal surfaces; Metallic Materials; Oxide coatings; Physicochemical Processes at the Interfaces; Surface charge; Tribology
• ISSN: 2070-2051; 2070-206X
• DOI: 10.1134/S2070205121050099

The corrosion behavior and hydrogen generation on aluminum in NaOH solutions are followed up using different techniques. The rates of Al 2 O 3 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/Al 2 O 3 interface. Low values of free energy of activation of these processes E a indicate that these processes are controlled by a diffusion step. The positive values of Δ H a reflect the endothermic nature of the activation processes, while the negative values of Δ S a indicate a decreased disordering of a dissociation step.