Trace Iron-Decorated Nitrogen/Sulfur Co-Doped Hierarchically Porous Carbon for Oxygen Reduction and Lithium–Sulfur Batteries

The development of non-precious metal-based electrocatalysts for oxygen reduction is essential for the practical applications of oxygen-involved electrochemical energy conversion and storage devices. In this work, we report the synthesis of trace iron-decorated nitrogen/sulfur co-doped hierarchically porous carbon through pyrolysis of a polymer network with impregnated silica nanoparticles, zinc acetate, and ferric nitrate, followed by the removal of templates and isolated iron particles. Both micropores and mesopores exist in the thus-synthesized materials with a specific surface area of 1055 m2 g–1. The synthesized electrocatalyst exhibits a promising electrocatalytic activity toward oxygen reduction reactions under both alkaline and acidic conditions as evidenced by half-wave potentials and limiting current density. The half-wave potential of the synthesized material is about 44 mV higher and about 60 mV lower than that of Pt/C under alkaline and acidic conditions, respectively. Moreover, the synthesized material is more electrochemically stable than the commercial Pt/C under both alkaline and acidic conditions. In addition, the synthesized material displays a capacity of 1130 mA h g–1 at 0.2 C as a sulfur host in a Li–S battery, and the capacity decay is 0.114% per cycle at 1.0 C over 400 cycles.