Ni2P nanoparticles encapsulated in carbon nanotubes as high-performance electrocatalyst for rechargeable zinc-air battery

Designing electrocatalysts with high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance for rechargeable Zn-air batteries (RZAB) is significant yet challenging. Herein, Ni-based phosphide (Ni2P) nanoparticles encapsulated in carbon nanotubes (Ni2P/CNTs) are prepared via chemical vapor deposition (CVD) and phosphating methods. The optimized Ni2P/CNTs exhibit a higher half-wave potential of 0.859 V for ORR and a lower overpotential of 304 mV at 10 mA cm-2 for OER in 1.0 M KOH than reference catalysts, respectively. Furthermore, the RZAB assembled using the Ni2P/CNTs shows a considerable open circuit potential of 1.42 V and a potential power density of 153 mW cm-2, which are higher than commercial Pt/C + RuO2 based batteries.