Assembling Amorphous Metal–Organic Frameworks onto Heteroatom‐Doped Carbon Spheres for Remarkable Bifunctional Oxygen Electrocatalysis

Abstract

AbstractMultifunctional electrocatalysts play an increasingly crucial role in various practical electrochemical energy conversion devices. Especially, on the air cathode of rechargeable zinc–air batteries (ZABs), oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), requiring efficient bifunctional electrocatalysts, are switched during discharging and charging process. Here, supported by the theoretical computations, a facile strategy for the in situ assembly of NiFe‐MOFs nanosheets on heteroatoms‐doped porous activated carbon spheres is developed. The newly designed electrocatalyst (NP‐ACSs@NiFe‐MOFs) shows excellent performance toward bifunctional oxygen electrocatalysis. Specifically, a remarkable low value of potential gap (ΔE= 0.61 V), which is the difference between the potential to reach an OER current density of 10 mA cm−2and ORR half‐wave potential, is achieved in 0.1 mKOH. Notably, the aqueous ZAB based on NP‐ACSs@NiFe‐MOFs shows super cycle stability with small voltage gap of only 0.79 V when cycled for 450 h at 10 mA cm−2. Also, the quasi‐solid‐state ZAB indicates excellent flexibility and cycling stability. This study presents a facile strategy for the rational integration of different catalytically active components, and can be extended to prepare other strongly competitive multifunctional electrocatalysts.