Ruthenium Oxide Incorporated One-Dimensional Cobalt Oxide Composite Nanowires as Lithium-Oxygen Battery Cathode Catalysts

Abstract

Ruthenium oxide/cobalt oxide composite nanowires (RuO2/Co3O4 NWs) have been synthesized through a simple and efficient electrospinning method for use as bifunctional electrocatalysts in rechargeable lithium-oxygen (Li-O-2) battery cathodes. The as-prepared NWs have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure (XANES) spectroscopy. The intrinsic activities of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) over the obtained composite NWs are studied using a rotating-disk electrode technique. The RuO2/Co3O4 NWs exhibit superior bifunctional electrocatalytic activities for both the ORR and the OER if compared to the activities of the Co3O4 NWs and only Ketjenblack (KB). If the RuO2/Co3O4 NWs are employed as cathode catalysts in Li-O-2 cells, great improvements in terms of the discharge capacity, coulombic efficiency, and cycle stability with low discharge-charge overpotentials are achieved. These can be attributed to the high bifunctional catalytic activities of the RuO2/Co3O4 composite NWs.