Rational design of electrocatalysts to replace the noble-metal-based materials for oxygen reactions is highly desirable but challenging for rechargeable metal–air batteries. Herein, we demonstrate a unique two stage encapsulation strategy to regulate the structure and performance of catalysts featured with thin graphene nanosheets coupling with full encapsulated ultrafine and high-loaded (∼25 wt %) transition metal nanoparticles (TMs@NC X ) for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). By optimizing the electronic modulation effect from suitable metal cores, the best NiFe@NC X catalyst exhibits high stability and activity with an onset potential of 1.03 V for ORR and an overpotential of only 0.23 V at 10 mA cm –2 for OER, which is superior to commercial Pt/C and IrO 2 catalysts. Rechargeable Zn–air battery using NiFe@NC X catalyst exhibited an unprecedented small charge–discharge overpotential of 0.78 V at 50 mA cm –2, high reversibility, and stability, holding great promise for the practical implementation of rechargeable metal–air batteries.
No takes yet. Share an insight, caveat, or question.
Zhu et al. (2016) studied this question.