Three-Dimensional Graphene-Supported Ni 3 Fe/Co 9 S 8 Composites: Rational Design and Active for Oxygen Reversible Electrocatalysis

The development of low-cost and efficient electrocatalysts with a bicomponent active surface for reversible oxygen electrode reactions is highly desirable and challenging. Herein, we develop an effective calcination-hydrothermal approach to fabricate graphene aerogel-anchored Ni Fe-Co S bifunctional electrocatalyst (Ni Fe-Co S /rGO). The mutually beneficial Ni Fe-Co S bifunctional active components efficiently balance the performance of oxygen reduction and oxygen evolution reactions (ORR/OER), in which Co S promotes the ORR and Ni Fe facilitates the OER. This balance behavior has an obvious advantage over that of monocomponent Ni Fe/rGO and Co S /rGO catalysts. Meanwhile, the additional synergy between porous rGO aerogels and Ni Fe-Co S endows the composite with more exposed active sites, faster electrons/ions transport rate, and better structural stability. Benefiting from the reasonable material selection and structural design, the Ni Fe-Co S /rGO exhibits not only outstanding ORR activity with the high onset- and half-wave potentials ( E = 0.91 V and E = 0.80 V) but also satisfactory OER activity with a low overpotential at 10 mA cm (0.39 V). Moreover, rechargeable Zn-air cells equipped with Ni Fe-Co S /rGO exhibit excellent rechargeability and a fast dynamic response.