From S-rich polyphenylene sulfide to honeycomb-like porous carbon with ultrahigh specific surface area as bifunctional electrocatalysts for rechargeable Zn-air batteries

Abstract

Porous carbon materials possessing high specific surface area (SSA) are promising electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable Zn-air batteries. However, it is difficult to synthesize porous carbon with high SSA and endow them with high catalytic activity. Herein, Fe, N, S co-doped honeycomb-like porous carbon (Fe–N/S-HPC) with ultrahigh SSA (2223.31 m2 g−1) was achieved through a combined process of KOH activation and pyrolysis using S-rich polyphenylene sulfide (PPS) fibers as precursors. The ultrahigh SSA of Fe–N/S-HPC greatly increases the electrode/electrolyte contact area, while the introduction of heteroatoms (Fe, N, and S) as highly efficient active centers enables the efficient catalytic activity of Fe–N/S-HPC. Notably, the introduced metal presents a unique core-shell structure in Fe–N/S-HPC, with FexOySz as the shell and FexNySz as the core, which can great improve the catalytic activity and durability. Under alkaline conditions, the Fe–N/S-HPC catalyst exhibited outstanding bifunctional oxygen catalytic performance and facilitates the practical application of rechargeable Zn-air batteries. This study not only provides a solution for the rational utilization of PPS fiber waste does not decompose in nature, but also provides new insights for the construction of ultrahigh SSA porous carbon that is needed for industrial applications of rechargeable Zn-air batteries.