Iron phthalocyanine coupled with nickel-iron selenide layered hydroxide derivative as dual-functional oxygen electrocatalyst for rechargeable zinc-air batteries

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for dual-functional non-precious metal electrocatalysts are promising alternatives for Pt/Ru-based materials in rechargeable zinc-air batteries (ZABs). However, how to achieve dual-functional oxygen electrocatalytic activity on single-component catalysts and identify the sites responsible for ORR and OER still face many challenges. Herein, an efficient and stable dual-functional electrocatalyst is fabricated by a two-step hydrothermal method with iron phthalocyanine (FePc) π-π stacking on nickel-iron selenide layered hydroxide derivatives (Se/Ni3Se4/Fe3O4). The as-prepared multi-component catalyst (named as FePc/Se@NiFe) exhibits better oxygen electrocatalytic properties than Pt/Ru-based catalysts, with a half-wave potential (E1/2) of 0.90 V and an overpotential of 10 mA cm-2 (Ej10) of 320 mV. More importantly, chronoamperometry (I-T) and accelerated durability tests (ADT) show the unordinary stability of the catalyst. Both physical characterization and experimental results verify that the Fe-N4 moieties and Ni3Se4 crystalline phase are the main active sites for ORR and OER activities, respectively. The small potential gap (ΔE = Ej10 - E1/2 = 0.622 V) represents superior dual-functional activities of the FePc/Se@NiFe catalyst. Subsequently, the ZABs assembled using FePc/Se@NiFe exhibit excellent performances. This study offers a promising design concept for promoting further development of high-performance ORR and OER electrocatalysts and their application in ZAB.