Pyrolysis-free coupling strategy to synthesize two-dimensional oxygen reaction electrocatalysts for rechargeable Zn-air batteries

Abstract

Although rechargeable Zn-air batteries (ZABs) representing one of the most prospective energy devices, their practical applications are primarily restricted by sluggish oxygen reduction and evolution reactions (ORR/OER). We herein propose a pyrolysis-free coupling strategy to prepare two-dimensional ORR/OER bifunctional electrocatalysts, in which atomic Fe-N4 moieties from planar iron phthalocyanine molecules for ORR and ultrathin FeCo hydroxides for OER are anchored on graphene by ultrasound-assisted coupling interactions. The obtained catalyst exhibits a small OER-ORR potential difference of 0.64 V. When used in ZABs, excellent performance is achieved such as a large power density (216 mW cm−2), a high specific capacity (743 mAh g−1), and stable charge–discharge voltage platform, demonstrating its great potential in the applications of energy devices.