Lawrence Berkeley National Laboratory

Highly active and durable electrocatalysts are of great significance to accelerate the sluggish oxygen evolution and oxygen reduction reaction (OER and ORR) which are indispensable processes in practical devices such as metal–air batteries. Herein, the authors integrate morphological design with compositional manipulation, and successfully achieve well-defined CoNiFe sulfide mesoporous nanospheres (CoNiFe-S MNs). The as-prepared CoNiFe-S MNs exhibit superior OER and ORR catalytic activity, delivering a low overpotential of only 199 mV at a current density of 10 mA cm−2 in 1 m KOH solution and a half-wave potential of 0.78 V in 0.1 m KOH solution toward OER and ORR, respectively. The CoNiFe-S MNs involved Zn–air battery exhibits remarkable charge–discharge performance (voltage gap of 0.76 V at 2 mA cm−2) and high power density (over 140 mW cm−3). Extended-time durability tests validate the structural recoverability of the mesoporous morphology, and the remarkable performance can be attributed to the intrinsic synergistic effect of heterometallic ions. It is believed that the method could pave the way for the design of novel electrocatalysts for Zn–air batteries.