Nanostructured doped ceria for catalytic oxygen reduction and Li2O2 oxidation in non-aqueous electrolytes

Abstract

Herein, we report the catalytic activities of porous nano-crystalline oxides with surface active sites synthesized by a wet chemical route. Zr doped ceria (ZDC) has been tested as active oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts in air electrodes for Li–O₂ batteries. A ZDC-based air electrode exhibits a higher discharge capacity than that of a bare carbon-based air electrode. ZDC loaded in carbon air electrodes delivers a discharge capacity of 8435 mA h g⁻¹. The higher discharge voltages of Li–O₂ cells with ZDC, instead of bare carbon, could have originated from the higher oxygen reduction activity of ZDC. These oxides show a lower potential for Li₂O₂ oxidation than pure carbon. A significant increase in the kinetics for Li₂O₂ oxidation indicates the influence of the ZDC catalyst on the oxygen evolution reaction. The ORR and OER properties of the catalyst are explained in terms of the high fraction of active defect sites on its surface.