Hierarchical Core–Shell Co<sub>2</sub>N/CoP Embedded in N, P‐doped Carbon Nanotubes as Efficient Oxygen Reduction Reaction Catalysts for Zn‐air Batteries
Chongchao Yao, Jiaxin Li, Zhihao Zhang, Chunli Gou, Zhongshen Zhang, Gang Pan, Jing Zhang
Abstract
Abstract Projecting a cost‐effective and highly efficient electrocatalyst for the oxygen reaction reduction (ORR) counts a great deal for Zn‐air batteries. Herein, a hierarchical core–shell ORR catalyst (Co 2 N/CoP@PNCNTs) is developed by embedding cobalt phosphides and/or cobalt nitrides as the core into N, P‐doped carbon nanotubes (PNCNTs) as the shell via one‐step carbonization, nitridation, and phosphorization of pyrolyzing Co‐MOF precursor. The globally N, P‐doped structure of Co 2 N/CoP@PNCNTs demonstrates an outstanding electrocatalytic activity in the alkaline solution with the onset and half‐wave potentials of 1.07 and 0.85 V respectively. Moreover, a Zn‐air battery assembled from Co 2 N/CoP@PNCNTs as the air cathode delivers an open circuit potential of 1.49 V, a maximum power density of 151.1 mW cm −2 and a specific capacity of 823.8 mAh kg −1 . It is reflected that Co 2 N/CoP@PNCNTs provides a long‐term durability with a slight decline of 15 h in the chronoamperometry measurement and an excellent charge–discharge stability with negligible voltage decay for 150 h at 10 mA cm −2 in Zn‐air batteries. The results reveal that Co 2 N/CoP@PNCNTs has superiority over most Co‐N x ‐C or Co x P@C catalysts reported so far. The excellent catalytic properties and stability of Co 2 N/CoP@PNCNTs derive from synergistic effects between Co 2 N/CoP and mesoporous N, P‐doped carbon nanotubes.