The LSV plot of each catalyst was further corrected using the estimated electrochemically active surface area (ECSA) of each catalyst in order to determine the intrinsic activity of each material for OER(Figure ). Co3O4 has the highest ECSA out of all four catalysts, followed by Co1.7Al1.3O4, Co2.5Ga0.5O4 and then GaCo2O4. After adjusting for the ECSA of all catalysts (Figure ), Co2.5Ga0.5O4 starts outcompeting Co3O4 even earlier, at about 1.52VRHE.