Dual Heteroatom-Doped Carbon Nanofoam-Wrapped Iron Monosulfide Nanoparticles: An Efficient Cathode Catalyst for Li-O Batteries.

Cost-effective dual heteroatom-doped 3D carbon nanofoam-wrapped FeS nanoparticles (NPs), FeS-C, act as efficient bifunctional catalysts for Li-O batteries. This cathode exhibits a maximum deep discharge capacity of 14 777.5 mA h g with a 98.1 % columbic efficiency at 0.1 mA cm . The controlled capacity (500 mA h g ) test of this cathode delivers a minimum polarization gap of 0.73 V at 0.1 mA cm and is sustained for 100 cycles with an energy efficiency of approximately 64 % (1st cycle) and 52 % (100th cycle) at 0.3 mA cm , under the potential window of 2.0-4.5 V. X-ray photoelectron spectroscopy reveals the substantial reversible formation and complete decomposition of Li O . The excellent recharging ability, high rate performance, and cycle stability of this catalyst is attributed to the synergistic effect of FeS catalytic behavior and textural properties of heteroatom-doped carbon nanostructures.