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 selfsacrificing 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(ΔE)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.