Interfacial Engineering of Leaf-like Bimetallic MOF-Based Co@NC Nanoarrays Coupled with Ultrathin CoFe-LDH Nanosheets for Rechargeable and Flexible Zn-Air Batteries

Abstract

Exploring high-efficiency, low-cost, and long-life bifunctional self-supporting electrocatalysts is of great significance for the practical application of advanced rechargeable Zn-air batteries (ZABs), especially flexible solid-state ZABs. Herein, ultrathin CoFe-layered double hydroxide (CoFe-LDH) nanosheets are strongly coupled on the surface of leaf-like bimetallic metal-organic frameworks (MOFs)-derived hybrid carbon (Co@NC) nanoflake nanoarrays supported by carbon cloth (CC) via a facile and scalable method for rechargeable and flexible ZABs. This interfacial engineering for CoFe-LDHs on Co@NC improves the electronic conductivity of CoFe-LDH nanosheets as well as achieves the balance of oxygen evolution reduction (OER) and oxygen reduction reaction (ORR) activity. The unique three-dimensional (3D) open interconnected hierarchical structure facilitates the transport of substances during the electrochemical process while ensuring adequate exposure of OER/ORR active centers. When applied as an additive-free air cathode in rechargeable liquid ZABs, CC/Co@NC/CoFe-LDH-700 demonstrates high open-circuit potential of 1.47 V, maximum power density of 129.3 mW cm−2, and satisfactory specific capacity of 710.7 mAh g−1Zn. Further, the flexible all-solid-state ZAB assembled by CC/Co@NC/CoFe-LDH-700 displays gratifying mechanical flexibility and stable cycling performance over 40 h. More significantly, the series-connected flexible ZAB is further verified as a chain power supply for LED strips and performs well throughout the bending process, showing great application prospects in portable and wearable electronics. This work sheds new light on the design of high-performance self-supporting non-precious metal bifunctional electrocatalysts for OER/ORR and air cathodes for rechargeable ZABs.

A green synthetic approach: crystalline–amorphous interface CoFe-LDH as a sustainable electrocatalyst for water oxidation with low cell voltage and evaluation of its sustainability standards

“…6). [32][33][34][35] These ndings conrmed the electron transfer from Fe to Co atoms, and hence a Co-Fe synergistic effect may exist. The stronger Co-Fe synergistic effect in Co 4 Fe 6 -LDH gave rise to the best electrocatalytic performance towards the oxygen evolution reaction.…”

Synergetic Engineering of Metal–Organic Framework Derived FeNi Layered Double Hydroxides for Efficient and Stable Overall Water Splitting

“…To date, various strategies have been used to improve the OER performance of LDHs. In particular, LDH electrocatalysts with hierarchical structures composed of nanosheets synthesized with metal–organic frameworks as precursors exhibit ideal advantages as electrocatalysts for water splitting due to their large surface area and short mass transport diffusion length. , For example, to enhance species transit during electrochemical processes while assuring adequate exposure to electrocatalytically active sites, Ma et al created a three-dimensional (3D) hierarchical structure of Co@NC/CoFe-LDHs electrode. The electrocatalyst demonstrated a good OER performance and a low overpotential of 224 mV at a current density of 10 mA cm –2 .…”