Hollow twin shell nanocomposite of ultrafine Fe3(PO4)2 embedded N,P,S-doped hierarchical carbon as bifunctional oxygen electrocatalyst for Zn-air batteries

Abstract

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 excellent selectivity and durability, compared to the commercial benchmark catalyst (i. e. Pt/C and IrO2). 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.