Iron-cobalt dual atomic sites in N, P-codoped carbon nanobelts as a multifunctional catalyst for Zn-air/iodide hybrid batteries.

The exploration of high-performance and multifunctional catalysts is a key issue in Zinc-air/iodide hybrid battery (ZAIHB). In this study, iron‑cobalt dual atomic sites (DAS) embedded in a biomass-derived (N, P) heteroatom-codoped carbon nanobelt (NPCB) framework were designed as a multifunctional catalyst for ZAIHB. Theoretical analysis reveals that the structure matching on both dual-atomic-centers and local electronic engineering contribute to the promoted catalytic activities for oxygen and iodide redox reactions. In addition, the nitrogen (N)-, and phosphorus (P)-codoped carbon nanobelts contributed to the highly porous and freestanding substrate, which endowed rapid kinetics. Benefiting from the above advantageous features, FeCo DAS@NPCB exhibits the excellent multifunctional catalytic properties for oxygen/iodide redox reactions. The full ZAIHB battery with the FeCo DAS@NPCB cathode exhibited high energy efficiency (77.4 %) and a long cycle life (over 300 h). Moreover, the solid-state ZAIHB with a hydrogel electrolyte showed good flexibility and stability during charge/discharge cycling. More impressively, the cell shows high reliability during the transition from exposure to air to an oxygen free environment with the replacement of oxygen reduction reaction (ORR) by iodide reduction reaction (IRR). This unique mechanism results in the high adaptability of the fabricated ZAIHB to serve multifarious working environments. Therefore, this study introduces a novel strategy for the design and construction of multifunctional catalysts, and promotes the rapid development of highly efficient ZAIHB for diverse electronics.