Synergistic coupling of FeS/FeNi nanoparticles with 3D N, S dual-doped porous carbon network for bifunctional ORR/OER electrocatalysts and zinc-air batteries

Exploring efficient and durable non-noble metal catalysts toward oxygen reduction/evolution reaction (ORR/OER) is of practical significance in advancing Zn-air batteries. Herein, we introduce a three-dimensional (3D) bifunctional electrocatalyst (Fe/Ni@NSC) consisting of N, S-dual doped mesoporous carbon nanosheets/carbon nanotubes embedded with abundant FeS/FeNi nanoparticles and Fe/Ni-N x sites by integrating rod-like ZIF-L@S-g-C 3 N 4 with Fe/Ni-phen complex and subsequent pyrolysis. The 3D structure not only offers a high surface area for active sites but also accelerates O 2 transport/charge transfer. Leveraging the synergistic effect of the 3D porous carbon network and multiple active sites, Fe/Ni@NSC exhibited outstanding activities in both ORR (half-wave potential, 0.868 V) and OER (overpotential, 317 mV at 10 mA cm −2 ), indicating a low potential gap of 0.679 V, outperforming the Pt/C + RuO 2 benchmarks (0.695 V). The Zn-air batteries based on Fe/Ni@NSC achieved a promising open circuit voltage (1.47 V), peak power density (172.59 mW cm −2 ), as well as long-term cycling stability (370 h). Furthermore, density functional theory (DFT) calculations also demonstrated that the interfacial electronic interaction between FeS and FeNi effectively boosted the bifunctional catalytic performance for ORR/OER. This study lays the foundation for designing low-cost and efficient 3D structure non-noble metal catalysts for more energy conversion and storage devices.