AL BACHA, Serge; DESMEDT, Arnaud; ZAKHOUR, Mirvat; NAKHL, Michel; BOBET, Jean-Louis

doi:10.1016/j.elecom.2020.106813

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AL BACHA, Serge
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
Laboratoire de Chimie Physique des Matériaux [LCPM]
Plateforme de Recherche en NanoSciences et NanoTechnologie [PR2N]

DESMEDT, Arnaud
Institut des Sciences Moléculaires [ISM]

ZAKHOUR, Mirvat
Laboratoire de Chimie Physique des Matériaux [LCPM]
Plateforme de Recherche en NanoSciences et NanoTechnologie [PR2N]

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Electrochemistry Communications. 2020-10, vol. 119, p. 106813 (5 p.)

Elsevier

Résumé en anglais

Previous investigations (DFT calculations) showed that hydrogen atoms adsorption and H 2 desorption can occur on MgO and Al 2 O 3 and that H atoms can diffuse on Mg and Al surfaces. However, these three simultaneous actions, i.e. H adsorption, H diffusion and H 2 desorption, have not been experimentally proved. In this paper, we propose a mechanism of formation of H 2 during the corrosion of an intermetallic compound Mg 17 Al 12 in 3.5 wt. % NaCl aqueous solution based on in situ Raman spectroscopy analysis. We found that, through the passivation zone (e.g. E varying from the open circuit potential (OCP) to +100 mV/OCP), the oxide layer is destroyed in favor of the appearance of Mg and H atoms. Moreover, the formed H atoms are adsorbed on the oxide surface and then diffuse on either the oxide surface or the unreacted metal surface where they recombine forming H 2. In situ Raman measurements during anodic polarization experimentally prove, for the first time, the formation of a reaction intermediate which weakens the H-H bond. The obtained results explain the mechanism of hydrogen production under anodic polarization of the intermetallic compound at normal conditions of temperature and pressure.< Réduire

Mots clés en anglais

Hydrogen

Monovalent Mg

Corrosion

Mg17Al12

Raman

Mg+/MgH+

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Mechanism of hydrogen formation during the corrosion of Mg17Al12

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