One-step integration of Co-Ni phosphides in N, P co-doped carbons towards highly efficient oxygen electrocatalysis for rechargeable Zn-air battery

The development of highly efficient and robust bifunctional oxygen electrocatalysts is of great importance for optimizing the performance of rechargeable Zn-air batteries. In this study, Co?Ni phosphides encapsulated in N, P co-doped carbon (CoNiP/PNC) were prepared by a simple one-step pyrolysis method. The obtained catalyst exhibited outstanding oxygen reduction and oxygen evolution reaction (ORR and OER) activities in alkaline media. It exhibited a positive half-wave potential of 0.84 V versus the reversible hydrogen electrode for ORR, as well as a low overpotential of 470 mV to achieve 10 mA cm-2 for OER, comparable with the benchmark Pt/C and IrO2 catalysts. Furthermore, the rechargeable Zn-air battery was fabricated, which showed a high specific capacity of 729.3 mAh gZn-1, a high peak power density of 171.0 mW cm? 2, and good stability. It reveals that the interplay between heteroatom-doped carbon layers and Co?Ni phase leads to the high ORR activity, and the insitu formed bimetallic hydroxides/oxides contribute to the great OER performance. This work would inspire the future development of bifunctional electrocatalysts towards electrocatalysis in energy conversion and storage fields.

Automated summary

In this study, Co-Ni phosphides encapsulated in N, P co-doped carbon were prepared and exhibited outstanding ORR and OER activities. The interplay between heteroatom-doped carbon layers and Co-Ni phase contributed to the high ORR activity, while the in-situ formed bimetallic hydroxides/oxides enhanced the OER performance. This work serves as an inspiration for the future development of bifunctional electrocatalysts in energy conversion and storage fields.