First-Principles Investigation into the Contributions of ORR and HER in Magnesium Corrosion

Abstract

Recent experiments have demonstrated that oxygen reduction reaction (ORR) can contribute significantly to Mg corrosion in addition to hydrogen reduction reaction (HER). However, its contributions at various stages of Mg corrosion remains unclear. Using DFT calculations, we investigate ORR and HER on both pristine and Fe/Mn alloyed Mg, MgO and Mg(OH) 2 during Mg corrosion. We found that both HER and ORR on pristine and alloyed Mg contribute to the overall cathodic current density: HER contributes much more significantly than ORR, while the ORR contribution is up to the mass transport limit and would diminish over time. In addition, we found that ORR activities on Fe/Mn alloyed MgO are high, suggesting an alternate source of cathodic ORR contribution during the whole course of Mg corrosion. Excellent agreements are found between our findings and a recent experiment. Examined HER and ORR contributions to Mg corrosion using DFT. Evaluated HER and ORR cathodic current densities on Mg, MgO & Mg(OH) 2 . HER contributes mainly to Mg corrosion; ORR is up to mass transport. Identified ORR on alloyed MgO contributes to Mg corrosion significantly.