Spatially confined sub-nanometer Pt in RuO2 nanosheet as robust bifunctional oxygen electrocatalyst for stabilizing Li-O2 batteries

Developing a highly active and durable bifunctional oxygen catalyst is the key to boosting lithium-oxygen batteries, but it remains a grand challenge. Herein, we demonstrate a remarkably active and durable bifunctional electrocatalyst (Pt/RuO2/G) with highly exposed active sites for stabilizing Li-O-2 batteries by synergistically coupling the advanced oxygen reduction reaction (ORR) catalyst Pt with the oxygen evolution reaction (OER) catalyst RuO2, strongly anchored on graphene. The combined merits, including 2D porous morphology, ultrathin thickness (similar to 2.5 nm), and a well-dominated (110) plane of ultrasmall RuO2, originating from the efficient spatial confinement, provide the bifunctional Pt/RuO2/G electrocatalyst an extremely narrow OER/ORR voltage gap of only 0.633 V. Moreover, the as-designed Pt/RuO2/G-based Li-O-2 batteries deliver a low initial charge-discharge mid-capacity overpotential (0.78 V) and remarkable lifetime (2,200 h) at 200 mA g(-1), outperforming most Ru-based catalysts for Li-O-2 batteries. This work provides a reliable practical approach for high-performance Li-O-2 batteries.