3d orbital electron engineering in oxygen electrocatalyst for zinc-air batteries

The optimization of 3d electron configurations is considered a feasible approach to improve the catalytic activity of transition metal nitrogen carbon (TM–N–C) electrocatalysts. Herein, by stacking Fe-Ni dual-metal on carbon substrate to obtain (Fe, Ni)@N-MWCNTs as model objects, we reveal that Fe3+ with high spin in Fe-Ni sites which possesses 3d electron configurations suitable for both OER and ORR. Specifically, the metal sites can be effectively activated by both 3d electron configurations optimization and the charges donated from the carbon substrate, which can balance the competition between OER and ORR process, rendering the excellent bifunctional performances with a small potential difference (ΔE = 0.828 V). In addition, it further provides an excellent performance and cycling stability in aqueous zinc-air batteries. The assembled wearable flexible zinc-air batteries also provide stable cycling performance and can be worn as a wristband to light up LED lights.