Scalable synthesis and excellent catalytic effect of hydrangea-like RuO2 mesoporous materials for lithium–O2 batteries

Abstract A facile synthesis of hydrangea-like hierarchical microstructure formed from mesoporous RuO 2 nanoplates has been firstly developed, based on a self-assemble method and subsequent calcination. This RuO 2 material displays excellent catalysis towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in Li–O 2 batteries, because of increased catalytic sites, improved Li + ions and electrons transport, and existence of electrolyte-filled intersheet zones between RuO 2 sheets that will supply electrolyte to compensate for the evaporation of electrolyte. Specifically, the cell with the mesoporous RuO 2 as carbon-free catalyst can deliver about 1000 and 700 mA h g –1 for the first and 100th cycle, respectively. Also, the cell used the RuO 2 material as catalyst shows good rate capability with a capacity of about 500 mA h g –1 even at the current density of 1000 mA g –1 . The good electrochemical performance suggests that the unique hierarchical mesoporous RuO 2 could be a promising catalyst for future application in Li–O 2 batteries.