High-Performance Trifunctional Electrocatalysts Based on FeCo/Co2P Hybrid Nanoparticles for Zinc-Air Battery and Self-Powered Overall Water Splitting

Currently, it is still a significant challenge to simultaneously boost various reactions by one electrocatalyst with high activity, excellent durability, as well as low cost. Herein, hybrid trifunctional electrocatalysts are explored via a facile one-pot strategy toward an efficient oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The catalysts are rationally designed to be composed by FeCo nanoparticles encapsuled in graphitic carbon films, Co2P nanoparticles, and N,P-codoped carbon nanofiber networks. The FeCo nanoparticles and the synergistic effect from Co2P and FeCo nanoparticles make the dominant contributions to the ORR, OER, and HER activities, respectively. Their bifunctional activity parameter ( increment E) for ORR and OER is low to 0.77 V, which is much smaller than those of most nonprecious metal catalysts ever reported, and comparable with state-of-the-art Pt/C and RuO2 (0.78 V). Accordingly, the as-assembled Zn-air battery exhibits a high power density of 154 mW cm(-2) with a low charge-discharge voltage gap of 0.83 V (at 10 mA cm(-2)) and excellent stability. The as-constructed overall water-splitting cell achieves a current density of 10 mA cm(-2) (at 1.68 V), which is comparable to the best reported trifunctional catalysts.