MOF-derived CoP-nitrogen-doped carbon@NiFeP nanoflakes as an efficient and durable electrocatalyst with multiple catalytically active sites for OER, HER, ORR and rechargeable zinc-air batteries

Highly active, long-lasting, and low-cost nanostructured catalysts with efficient oxygen evolution and oxygen reduction reactions (OER and ORR) are critical for achieving high-performance zinc-air batteries. Herein, we developed CoP-nitrogen-doped carbon@NiFeP nanoflakes (CoP-NC@NFP), derived from MOF enriched with multiple active sites, for multifunctional water splitting and zinc-air battery applications. The experimental results revealed that the multiple active catalytic sites of CoP-NC@NFP were responsible for the excellent chargetransfer kinetics and electrocatalytic performance with respect to water splitting. This performance is comparable to that of precious metal catalysts in alkaline electrolytes (OER: overpotential of 270 mV; HER: overpotential of 162 mV; ORR: Tafel slope of 46 mV dec- 1; overall water splitting device: cell voltage of 1.57 V at 10 mA cm- 2) with excellent electrochemical durability. Additionally, the structural stability of the OER and the HER durability of the CoP-NC@NFP electrocatalyst were confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) studies. Most impressively, zinc-air batteries (ZABs) assembled with CoP-NC@NFP as the air-cathode exhibit exceptionally high power density of 93 mW cm-2 and prolonged operational stability over 200 h compared with a ZAB equipped with a benchmark air-cathode. The outcome of this study opens a practical possibility for the preparation of efficient multifunctional catalysts free of noble metals for clean energy production and storage.