The GC study indicates significant differences in the amount of H2 produced in presence of O2 and N2 supplied anodic processes. H2 production is monitored in 20 minutes intervals. Upon assembling, the cell is left at OCP condition with N2 and O2 supply in two different sets (SI Appendix, Fig. ). The amount of H2 detected is higher in the N2 environment than in the O2 environment, as H2 detection is the result of parasitic corrosion reaction occurring on the Zn surface and initial defects propagate corrosion more easily. In the presence of O2, the parasitic ORR initiates defects on Zn surface that results in more corrosion on Zn surface initially but with the time, the parasitic ORR results in the surface passivation as noticed from decreased cell OCP from 1.42 V to 1.14 V within 90 minutes, whereas minute decrease in OCP (1.41 V) was observed in N2 rich condition. Even when the cell is discharged at higher current densities of 5 mA cm -2 , the observed H2 production in GC (Fig. ) is higher in the presence of N2 than that in the O2. It has been observed that H2 formation remains significantly higher in the N2 while it diminishes consistently in O2 as the cell goes towards the failure and reaches to 0 ppm as the cell failed completely in O2 due to complete passivation. It is also observed that switching the supplied gas from N2 to O2 rapidly reduces the amount of H2. In the O2 environment, some of the surface sites undergo side reactions with oxygen, as mentioned before, resulting in less sites available for HER. After the O2 supply, while the further backing of N2 doesn't retrieve the H2 formation (SI Appendix, Fig. ). It is evident from here that the more active Zn surface is exposed in anodic N2 supplied environment. Hence, in the presence of O2 gas, ORR and HER appear as the side reactions of the ZAB. However, by eliminating the O2 reaching at the anode surface, HER stays as the dominant side reaction. This also indicates that O2 reduction is the major parasitic process in the alkaline ZAB than HER. Effective reduction of ORR process in ZAB by protecting the Zn surface can prolong the cell cyclability and energy density (capacity * voltage).