Hierarchical Core–Shell Co₂N/CoP Embedded in N, P‐doped Carbon Nanotubes as Efficient Oxygen Reduction Reaction Catalysts for Zn‐air Batteries

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 (Co2N/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 Co2N/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 Co2N/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 Co2N/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 Co2N/CoP@PNCNTs has superiority over most Co‐Nx‐C or CoxP@C catalysts reported so far. The excellent catalytic properties and stability of Co2N/CoP@PNCNTs derive from synergistic effects between Co2N/CoP and mesoporous N, P‐doped carbon nanotubes.

A Review of One‐Dimensional Nanomaterials as Electrode Materials for Oxygen Reduction Reaction Electrocatalysis

“…In addition to the doping of carbon nanotubes with single-component active sites, the development of multi-component synergistic electrocatalysts has also received extensive attention. Yao et al [70] prepared core-shell nanotube-like Co 2 N/CoP@PNCNTs electrocatalysts by pyrolysis using dicyandiamide as the N-doping source and NaH 2 PO 2 as the P-doping source (Figure 5d). The ECSA of Co 2 N/ CoP@PNCNTs was 5.20 cm 2 , which was higher than that of Co 2 N@NCNTs without CoP doping (3.96 cm 2 ).…”

Solution plasma synthesis of perovskite hydroxide CoSn(OH)6 nanocube electrocatalysts toward the oxygen evolution reaction

“…Carbon materials doped with N, B, P have been developed and have achieved high performance in the ORR. 11–18 In addition, it is possible to improve the ORR characteristics by including a metal–N–C bond in the carbon material. 19–24…”

“…Carbon materials doped with N, B, P have been developed and have achieved high performance in the ORR. [11][12][13][14][15][16][17][18] In addition, it is possible to improve the ORR characteristics by including a metal-N-C bond in the carbon material. [19][20][21][22][23][24] Noble metal oxides such as RuO 2 and IrO 2 have been used as catalyst materials for the oxygen evolution reaction (OER) of metalair cells, but these compounds have problems in terms of resource quantity and raw material cost, so they are scarcer and more expensive.…”

A honeycomb carbon substrate anchored with Sn and Sb bimetallic atoms boosts oxygen-reduction electrocatalysis

“…The excellent ORR performance of SnSb-NC may be due to the synergistic effect between metals that changes the adsorption energy of the oxygen intermediate at the active site. 42,43 When tested in a Zn-air battery with the SnSb-NC catalyst as the positive electrode, the battery displayed favorable cycling stability (1106 hours), suggesting its potential use in electrocatalytic reactions related to energy.…”