FeP/Fe2P heterojunction embedded in N, S, P-doped carbon structure as oxygen reduction reaction electrocatalysts for zinc-air batteries

Abstract

Constructing transition metal compounds (TMC) in carbon-based materials is a desirable strategy for developing efficient oxygen reduction reaction (ORR) electrocatalysts, while the lacked a feasible synthesis method and its unclear catalytic mechanism put a challenge. Here, we report a FeP/Fe2P heterojunction embedded in N, S, P-doped carbon (FeNSPC) catalyst by facile in-situ pyrolysis. Compared with the control sample FeP/Fe2P heterojunction embedded in N, P-doped carbon (FeNPC), the FeNSPC presents higher ORR activity. Furthermore, the S-doping strategy modulates the electronic structure of FeP/Fe2P heterojunction and carbon matrix (the charge distribution/spin density redistribution), thereby endowing a superior ORR activity of FeNSPC. Specifically, the FeNSPC1000 possesses a half-wave potential of 0.83 V. Meanwhile, the FeNSPC1000 only loses 14 mV of the half-wave potential after 3000 cycles, and the relative current of FeNSPC1000 remains 87.8 % after 8 h i-t-test. Moreover, the FeNSPC1000 assembled ZAB shows excellent performance with a specific capacity of 702 mA h g−1 and an energy density of 737 W h kg−1.