Regulating electron region of central Fe atom in iron phthalocyanine by N, S-doped carbon nanofibers as efficient oxygen reduction catalysts for high-performance Zn-air battery

Abstract

Rational design effective and durable non-noble metal-based oxygen reduction reaction (ORR) electrocatalyst is significant and urgent. Herein, the nanostructure consisting of monomeric FePc and one-dimensional N, S co-doped carbon nanofiber (NSCNF) modified with CeO2 was synthesized based on the rational strategy and component regulation. Specifically, the wrapped CeO2 nanoparticles optimize the chemical environment of composite. NSCNF further modulates the electronic environment of iron centers of FePc for accelerating the electron transfer and optimizes the free energies of oxygen intermediates. The resulting FePc@CeO2/NSCNF provides the distinct conductive pathway, high mechanical, and chemical stability, thus preventing the aggregation and dissolution of the active Fe sites during the reaction. More importantly, the S, N-doped carbon, uniform dispersion of Fe sites, and CeO2 synergistically contribute to the overall ORR performance. As expected, the FePc@CeO2/NSCNF demonstrates excellent ORR activity with the onset potential (Eonset) of 1.00 V, half-wave potential (E1/2) of 0.89 V, and good durability. Furthermore, the assembled rechargeable aqueous and flexible solid-state Zn-air batteries using FePc@CeO2/NSCNF electrode deliver outstanding battery performance and good cycling stability, indicative of its potential feasibility for next-generation electronic devices.