Ion exchange coupled biomineral self-sacrificial template synthesis of N-enriched porous carbon as robust electrocatalyst for rechargeable Zn-air battery

To realize the commercialize of rechargeable Zn-air battery (RZAB), developing metal-free bifunctional electrocatalysts with satisfactory activity for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the emerging issues. Herein, a prawn shells-derived N-enriched porous carbon (PSNC) is synthesized via an ion exchange coupled biomimetic self-sacrificing template strategy. The resulting PSNC displays unique functional components, including the interconnected macro-meso-micropores structure to shorten charge and mass transfer pathway, high content of pyridinic and graphitic nitrogen to construct rich catalytic active site and improve conductivity. As electrocatalysts in alkaline condition, the optimized PSNC-0.8 achieves excellent bifunctional catalytic propriety with a narrow potential gap (Δ E ) value of 0.80 V. Meanwhile, PSNC-0.8-based RZAB displays a high peak power density of 176.5 mW·cm −2 and considerable cycling durability with a small battery efficiency delay of 6.5% after 480 cycles (320 h). This study enlightens a simple and effective conception to design high-performance metal-free bifunctional electrocatalysts from seafood waste. Graphical abstract