Coupling of iron (II) phthalocyanine and layered double hydroxide via carbon nanotubes media with pyrolysis-free for high-stability rechargeable zinc-air batteries.

Abstract

Developing high-efficiency bifunctional electrocatalysts capable of overcoming the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is an urgent challenge for rechargeable zinc-air batteries (RZABs). Herein, we successfully prepared an excellent bifunctional catalysts through facile pyrolysis-free method. Nickel/iron layered double hydroxide (NiFe-LDH) with OER activity was in situ grown on carbon nanotubes (CNTs) and iron (II) phthalocyanine (FePc) with ORR activity was introduced through π-π interaction and covalent functionalization. Furthermore, the intervention of CNTs transform the electronic structure of NiFe-LDH to further enhance OER activity, while solve the problems of poor electrical conductivity and aggregation of FePc. The prepared bifunctional catalyst FePc-LDH@CNTs exhibits preeminent electrocatalystic performance for ORR (E_1/2 = 0.815 V) as well as OER (E_j=10 = 1.447 V). It displays a prominent bifunctionality which ΔE is only 0.632 V. Moreover, the liquid RZABs based on the FePc-LDH@CNTs demonstrate a significant specific capacity (810.4 mAh g^-1) and robust stability (840 h), superior to commerical Pt/C + RuO₂. As flexible RZABs, it maintains superb stability (100 h) and can drive water splitting to produce H₂ smoothly. In addition, the reasons for the failure are dissected by analyzing the components of the battery after cycles. This study provides a novel facile direction to prepare high-efficient and stable bifunctional oxygen electrocatalysts without pyrolysis.