Bimetallic CoZn Nanocrystals Embedded in N-Doped Graphene Layers as Electrocatalysts for Oxygen Reduction Reaction

Abstract In this work, highly active CoZn nanocrystals embedded in N-doped graphene layers (CoZn@NG-nPVP) towards oxygen reduction reaction (ORR) were synthesized through pyrolysis of bimetallic zinc cobalt Prussian blue analogues (i.e., Zn 3 [Co(CN) 6 ] 2 -nPVP), which consists of coordination band between zinc and [Co(CN) 6 ] 3− , with PVP as a structure regulator. The obtained CoZn@NG-nPVP samples display three-dimensional porous microsphere structures. Compared with CoZn@NG samples derived from Zn 3 [Co(CN) 6 ] 2 without PVP, the CoZn@NG-nPVP samples derived from Zn 3 [Co(CN) 6 ] 2 -nPVP with PVP exhibit more carbon defects, larger BET specific surface area, and higher contents of pyridinic-N and graphitic-N, leading to the high activity of the catalyst. The onset potential of CoZn@NG-4PVP-900 catalyst towards ORR is 0.98 V (vs. RHE) and the half-wave potential is 0.87 V (vs. RHE), which are comparable with that of commercial Pt/C. In addition, the electrochemical stability of CoZn@NG-4PVP-900 is much higher than that of commercial Pt/C. Graphic Abstract