The global energy crisis coupling with the fast consumption of fossil fuels and the associated environmental issues, has stimulated extensive interest in searching for clean, efficient and sustainable energy storage and conversion systems. Producing oxygen through an oxygen evolution reaction (OER) process can be promising when effective catalysis of water oxidation into oxygen molecules could be achieved. Therefore, developing an efficient OER electro catalyst is vital to the new generation of electrochemical storage and conversion devices such as electrolyzers and metal-air batteries. There are still, however, several challenges that should be solved so that the electrochemical water oxidation process can be economically attractive. One of them is associated with the high overpotential and thereby energy loss at the electrode, where OER occur with a four-electron transfer route, according to the following overall reaction:
2H2O(l) → O2(g) + 4H+ + 4e- (1)
Oxygen reduction reaction (ORR), the reverse reaction of OER, also plays an important role in the electrochemical energy storage and conversion field, including the fuel cells and the metal-air batteries. Advanced ABO3 perovskite oxides with improved catalytic properties have been extensively developed and modified as bifunctional catalysts because of their high versatility in composition, crystalline and electronic structure. In this presentation, Iridum doped (La0.8Sr0.2)1-xMn1-xIrxO3 (x=0, 0.05) and Cobalt doped (La0.8Sr0.2)1-xMn1-xCoxO3 (x=0, 0.05, 0.10) nanoparticles with particle size of 50 nm were succesfully synthesized by the polymer-assisted chemcial solution method as superior bifuctional oxygen catalysts in alkaline solution. The ORR onset potential of the Iridium doped sample is around 0.92 V vs. RHE, which is only 50 mV negative shift relative to the state-of-the-art Pt/C catalyst, whilst the OER onset potential is around 1.55 V, which is comparable to that of the state-of-the-art IrO2 catalyst. The Cobalt doped samples show enhanced OER activity and reduced total potential, but inferior ORR efficiency.