Fe-N4 engineering of S,N co-doped hierarchical porous carbon-based electrocatalysts for enhanced oxygen reduction in Zn-air battery

The development of high-performance non-noble metal cathode catalysts is a cutting-edge approach for efficient energy conversion and storage devices. Here we describe a in-situ formed template-assisting method to prepare highly active yet stable electrocatalyst (FeSN-HPC), which possesses abundant Fe-N4 sites uniformly dispersed in S,N co-doped hierarchical porous carbon. Compared to commercial Pt/C in alkaline electrolyte, the sample FeSN-HPC displays a superior and enhanced oxygen reduction reaction (ORR) activity (0.86 V of half-wave potential) and stability (only 14 mV degradation of half-wave potential after durability tests). The high electrocatlytic activity of FeSN-HPC mainly originates from the synergistic effect of efficient N dopants (such as pyridinc N, graphitic N and FeII-N4) and the desirable hierarchical porous architecture. Expectedly, the primary Zn-air battery (ZAB) with the FeSN-HPC as cathode electrocatalyst exhibits an outstanding discharge performance with a maximal power density of 200 mW cm-2. Additionally, the sample FeSN-HPC also has promising application potential in solid and flexible ZAB.