Lattice oxygen behavior is further validated by running a control experiment with Pt/C in the same experimental condition (Figure ). Please note that Pt/C is free from any lattice oxygen and should show insignificant reduction current before OER starts and it is clear from Figure that there is only -26 µA/cm 2 in the potential range of 1.0 V to 1.5 V. The current enhances to -43 µA/cm 2 post 1.5 V where the reaction enters the OER regime i.e., 1.55 V. This control experiment clearly confirms that lattice oxygen evolves from perovskite catalyst and the reduction current in Figure and Figure is solely from lattice oxygen.