Hollow Twin Shell Nanocomposite of Ultrafine Fe3(Po4)2 Embedded N,P,S-Doped Hierarchical Carbon as Bifunctional Oxygen Electrocatalyst for Zn-Air Batteries

Here, a Fe3(PO4)2 encapsulated N,P,S-doped hollow dual shell structured carbon-based nanocomposite (H-PZS-Fe-850), with fully open super-macropores, was developed via a simple but efficient coating-activation synthesis strategy. The incorporation of Fe3(PO4)2 in the nanoshell of the composite endowed a fast electron and mass transport activity with the resultant catalyst. As a result, H-PZS-Fe-850 exhibited excellent electrocatalytic activity for both the oxygen reduction (ORR) and oxygen evolution reaction (OER) under alkaline conditions, coupled with super reaction selectivity and stronger long-term stability, compared to the commercial benchmark catalyst (i.e. Pt/C and RuO2). Meanwhile, H-PZS-Fe-850 also presented acceptable ORR performance in the acidic and neutral media. It could be translated to a high performance rechargeable Zn-air battery (ZAB), as evidenced by the prominent charge/discharge performance with long time charging-discharging cycles (>320 h), high specific energy density (827 Wh g-1Zn) and superior discharge power density (211 mW cm-2), exceeding those of Pt/C-IrO2 catalyzed battery. This work provides an attractive guide for the rational preparation of highly performance oxygen electrocatalysts with controlled composition and morphology, accelerating the real applications of ZABs