Vo-riched PrOx is anchored on graphene nanosheets with large specific surface area and high conductivity. Therefore, the active site of oxygen defect in Vo-riched PrOx could be fully exposed to promotes the adsorption and desorption of intermediates, accelerates electron transport, and reduces the reaction energy barrier for excellent OER/ORR activities.

Abstract

The slow reaction kinetics of Li−O is currently the most pressing technical obstacle to the development of lithium-oxygen batteries. The Li₂O₂′s growth/decomposition pathways dominate the battery performance and can be optimized by exploring efficient cathode catalysts. Herein, we prepare regular, polycrystalline, oxygen vacancy (V_O)-riched PrO_x uniformly anchored on few-layered graphene (FLG) nanosheets to boost the Li−O reactions. XRD, TGA, XPS, SEM, TEM, SEAD, and electrochemical test techniques are used to study their chemical composition, microstructure, battery performance, and the effect of FLG on the formation of polycrystalline and V_O. It is confirmed that FLG provides a large specific surface area and good electron transport. Moreover, it works as an anchoring substrate to transform PrO_x from single crystal to polycrystalline, which is beneficial for exposing catalytic sites and V_O and improving the battery performance. This unique composition and structure offer efficient active sites, accelerate electron transport, and regulate the Li₂O₂′s nucleation to form nanofilms or nanosheets on the catalyst. With this cathode catalyst, the battery achieved an ultralow total overpotential of 0.618 V, with a discharge capacity of 11489 mAh g⁻¹ in the ultimate-capacity mode and a superior cyclability of 85 cycles under the limited capacity of 500 mAh g⁻¹.