Prussian blue analogue-derived CoFe nanocrystals wrapped in nitrogen-doped carbon nanocubes for overall water splitting and Zn-air battery

Controllable synthesis of low-cost, highly effective and operationally durable multifunctional electrocatalysts for oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) is crucial for enhancing the efficiency of water splitting and metal-air batteries. Herein, well-defined bimetallic CoFe alloyed nanocrystals wrapped in nitrogen-doped graphitic carbon nanocubes (CoFe@N-GCNCs-700) are synthesized by pyrolysis of CoFe-based Prussian blue analogue nanocubes@phenolic resin. The resulting CoFe@N-GCNCs-700, as an advanced trifunctional catalyst, exhibits prominent electrocatalytic behaviors for ORR (0.802 V of half-wave potential), OER (273 mV of overpotential at 10 mA cm−2) and HER (91.5 mV of overpotential at 10 mA cm−2) in the alkaline solution. Furthermore, its practicability is further exploited by overall water splitting. The output voltage of only 1.63 V is demanded to achieve a current density of 10 mA cm−2. Besides, the CoFe@N-GCNCs-700 based rechargeable Zn-air batteries exhibit large peak power density (132.5 mW cm−2) and superior cycling stability (100 h without evident degeneration). This research offers some new prospects in fabrication of highly effective multifunctional catalysts for electrochemical energy applications. © 2020 Elsevier B.V.