Consistent high rate oxygen reduction reaction during corrosion of Mg-Ag Alloy

The oxygen reduction reaction (ORR) is faster during Mg corrosion when no barrier corrosion product layer against O2 diffusion formed on the Mg surface. However, in this work, we demonstrate that ORR can be also very fast in the case of thick corrosion product layer for Mg-Ag alloy by simultaneously measuring local concentration of H2 and O2 with micro-probes. The Ag-redeposits spreading through the interfacial Mg(OH)2 layer promoted ORR. The contribution of ORR to the corrosion of Mg-Ag alloy could reach around 30%. These findings emphasize the importance of considering the contribution of ORR during the corrosion of Mg alloys.