Engineering the performance of bifunctional oxygen electrocatalysts by modulating the electronic structure of Co2P for rechargeable Zn-air battery

To develop the high-efficiency and low-cost bifunctional electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is very important and challenging for the rechargeable Zn-air batteries (ZABs). The sluggish ion/electron transport kinetics observed during the OER and ORR processes with the Co2P electrocatalyst can be attributed to the strong binding force between the surface Co atoms and the adsorbed intermediates. Herein, the electronic structure optimization is conducted to enhance the ORR and OER electrocatalytic activities of Co2P nanoparticles by doping iron ions. The results show that the Fe doping enable adjust the electronic structure of the Co atom and lower the energy barrier of RDS. Compared with Co2P@NCNT, the (Co0.90Fe0.10)2P@NCNT exhibit higher onset and half-wave potential (0.92 and 0.85 V vs. RHE, respectively) during the ORR process, and lower overpotential (380 mV, the current density is 10 mA∙cm−2) during the OER process. As expected, the ZABs base on (Co0.90Fe0.10)2P@NCNT electrocatalyst display an outstanding specific capacity (928.50 mAh∙g−1Zn), and an excellent peak power density (246.8 mW∙cm−2). This promising work may contribute to the fabrication of efficient electrocatalyst for ZABs.