Nanostructured doped ceria for catalytic oxygen reduction and Li₂O₂oxidation 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-O 2 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 À1 . The higher discharge voltages of Li-O 2 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 Li 2 O 2 oxidation than pure carbon. A significant increase in the kinetics for Li 2 O 2 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.

Mechanistic study on the activity of manganese oxide catalysts for oxygen reduction reaction in an aprotic electrolyte

“…This is proposed to be due to its mesoporous character exhibiting coordinatively unsaturated Mn 3+ surface ions in combination with the comparably large a-Mn 2 O 3 particle diameters, which results in lower catalyst/carbon contact and hence less contribution of carbon to the ORR mechanism. This proposal is supported by recent reports on Zr doped ceria catalysts in TEGDME-based electrolyte [38], where surface Ce 3+ ions were suggested to act as active centers for oxygen adsorption and superoxide formation. Concerning the influence of the oxidation state, it was shown in X-ray absorption spectroscopy (XAS) and in situ infrared (IR) spectroscopy studies that the presence of different oxidation states of transition metals in Cr, Cr 2 O 3 as well as LaCrO 3 and IrO 2 catalysts has a positive influence on their catalytic activity for the OER process in ether-based and aqueous electrolytes, respectively [39,40].…”

Oxygen vacancies promoting the electrocatalytic performance of CeO2nanorods as cathode materials for Li–O2batteries

“…38,39 Owing to the easy shift between oxidized and reduced states and the highly efficient adsorption of superoxide radicals, CeO2 has been considered as one of the best promising catalyst candidates for promoting both the ORR and the OER in LOBs. [40][41][42] CeO2 have been explored in lots of work on the cathodes for LOBs, serving as not only a catalyst but also an "oxygen pump" to relieve oxygen insufficiency during the ORR. 43,44 However, the role of oxygen vacancies playing in improving the electrochemical performance of LOBs is still unravelled.…”

CeO2 Encapsulated by Iron, Sulfur, and Nitrogen‐Doped Carbons for Enhanced Oxygen Reduction Reaction Catalytic Activity

“…[6] Its excellent catalytic activity benefits from the excellent storage/deoxygenation capacity and a fast transition valence between Ce 3 + and Ce 4 + . [7] However, the application of individual CeO 2 as the electrochemical catalyst is limited mainly because of its low conductivity. [8] Researchers have proposed various strategies to solve this problem, more of which involve the introduction of advanced catalytic materials into CeO 2 , such as carbon-based materials and transition metalbased materials.…”