Interfacial redox reaction-directed synthesis of silver@cerium oxide core–shell nanocomposites as catalysts for rechargeable lithium–air batteries

Abstract A facile oxidation–reduction reaction method has been implemented to prepare pomegranate-like Ag@CeO 2 multicore–shell structured nanocomposites. Under Ar atmosphere, redox reaction automatically occurs between AgNO 3 and Ce(NO 3 ) 3 in an alkaline solution, where Ag + is reduced to Ag nanopartilces and Ce 3+ is simultaneously oxidized to form CeO 2 , followed by the self-assembly to form the pomegranate-like multicore–shell structured Ag@CeO 2 nanocomposites driven by thermodynamic equilibrium. No other organic amines or surfactants are utilized in the whole reaction system and only NaOH instead of organic reducing agent is used to prevent the introduction of a secondary reducing byproduct. The as-obtained pomegranate-like Ag@CeO 2 multicore–shell structured nanocomposites have been characterized as electro-catalysts for the air cathode of lithium–air batteries operated in a simulated air environment. Superior electrochemical performance with high discharge capacity of 3415 mAh g −1 at 100 mA g −1 , stable cycling and small charge/discharge polarization voltage is achieved, which is much better than that of the CeO 2 or simple mixture of CeO 2 and Ag. The enhanced properties can be primarily attributed to the synergy effect between the Ag core and the CeO 2 shell resulting from the unique pomegranate-like multicore–shell nanostructures possessing plenty of active sites to promote the facile formation and decomposition of Li 2 O 2 .