Synergistic Fe-Se Atom Pairs as Bifunctional Oxygen Electrocatalysts Boost Low-Temperature Rechargeable Zn-Air Battery.

Herein, we successfully construct bifunctional electrocatalysts by synthesizing atomically dispersed Fe-Se atom pairs supported on N-doped carbon (Fe-Se/NC). The obtained Fe-Se/NC shows a noteworthy bifunctional oxygen catalytic performance with a low potential difference of 0.698 V, far superior to that of reported Fe-based single-atom catalysts. The theoretical calculations reveal that p-d orbital hybridization around the Fe-Se atom pairs leads to remarkably asymmetrical polarized charge distributions. Fe-Se/NC based solid-state rechargeable Zn-air batteries (ZABs-Fe-Se/NC) present stable charge/discharge of 200 h (1090 cycles) at 20 mA cm -2 at 25 °C, which is 6.9 times of ZABs-Pt/C+Ir/C. At extremely low temperature of -40 °C, ZABs-Fe-Se/NC displays an ultra-robust cycling performance of 741 h (4041 cycles) at 1 mA cm -2 , which is about 11.7 times of ZABs-Pt/C+Ir/C. More importantly, ZABs-Fe-Se/NC could be operated for 133 h (725 cycles) even at 5 mA cm -2 at -40 °C.