Fe, N, S co-doped carbon network derived from acetate-modified Fe-ZIF-8 for oxygen reduction reaction

In this work, potassium acetate (KAc) was added during the synthesis of a Zn-Fe based metal-organic framework (Fe-ZIF-8) to increase the fixed amount of Fe while simultaneously enhancing the number of pores. Electrospinning was utilized to embed KAc-modified Fe-ZIF-8 (Fe-ZIF-8-Ac) into the polyacrylonitrile nanofiber mesh, to obtain a network composite (Fe@NC-Ac) with hierarchical porous structure. Fe@NC-Ac was co-pyrolyzed with thiourea , resulting in Fe, N, S co-doped carbon electrocatalyst . The electrochemical tests indicated that the prepared catalyst displayed relatively remarkable oxygen reduction reaction (ORR) catalytic activity, with an onset potential (E onset ) of 1.08 V (vs. reversible hydrogen electrode, RHE) and a half-wave potential (E 1/2 ) of 0.94 V, both higher than those of the commercial Pt/C (E onset  = 0.95 V and E 1/2  = 0.84 V), respectively. Assembled into Zn-air batteries, the optimized catalyst exhibited higher open circuit voltage (1.698 V) and peak power density (90 mW cm −2 ) than those of the commercial 20 wt% Pt/C (1.402 V and 80 mW cm −2 ), respectively. This work provided a straightforward manufacturing strategy for the design of hierarchical porous carbon-based ORR catalysts with desirable performance.