The advanced OER activity is attributed to the fact that in low temperature inter-connected structures have the benefit for giving faster charge transport, alkaline electrolyte be able to simply enter inside these inter-connected structures and facing the active sites easily in this reaction, this reaction can be improved by OER electrocatalytic activity 55. The spinel Co ferrite sintered at T^(?50?^o C) exhibited a lower overpotential compared with other as-synthesized spinel ferrite with sinter at different temperature (T^(?50?^o C-?450?^o C)). at lower temperature Co(OH)2 group is observed, this is significantly donates to the exposure of more active sites56. In other hand, the most of reported overpotential are apparently higher than that of these values of Co spinel ferrites comparison between Co-based electrocatalyst is summarized in Table.
4. For cobalt ferrite, bellow at 250oC shows different structure of Co(OH)2, Co2O3, Fe-OOH, and ?-Fe2O3 mixture exhibit a low OER activity in alkaline media, these four phases could also involvement an equal phase transformation to the oxyhydroxide phase.