52 / 2019-09-30 14:27:25

Two Dimension ZIF-derived Ultra-thin Cu-N/C Nanosheets as High Performance Oxygen Reduction Electrocatalysts for High-Performance Zn-Air Batteries

two-dimensional zeolitic-imidazolate frameworks; N-Cu(II)-Cu(0); Cu-N-C; ultra-thin carbon layer; primary Zn-air batteries

Bottom-up construction of high-performance and long-term durability transition copper-nitrogen-carbon (Cu-N-C) electrocatalysts for oxygen reduction reaction (ORR) still remains great challenge. Herein, we propose a temperature-controlled with confinement effect synthesis strategy for fabrication of a novel two-dimension dual-metal (Cu/Zn) zeolitic imidazolate frameworks material, which presents an ultrathin nanosheet morphology after high-temperature thermal treatment (denoted as Cu-N-UNS). By controlling the reaction temperature as well as regulating the ratio of metal ions and taking advantages of the confinement effect of surfactants, the rational-designed ultra-thin carbon layer not only prevents aggregation of the transition Cu particles and avoids direct contact with reactants and electrolyte solutions to enhance the durability of electrocatalyst, but also shortens the electronic transmission path between active transition metal species and carbon surface. Therefore, the electrocatalyst exhibits excellent electrocatalytic performance for ORR (E1/2≈0.898 V), which is superior to those of state-of-the-art benchmark noble-metal electrocatalysts. Moreover, the evenly distribution of Cu-N-C and existence of N-Cu(II)-Cu(0) active sites make a great contribution to the electrocatalyst activity. Notably, the implementation of Cu-N-UNS serves as bifunctional air electrodes for Zn-air batteries also performs a high peak power density of ≈134.7 mW cm-2 at current density of ≈231.9 mA cm-2 with a remarkable durability.

Foundation: National Natural Science Foundation of China (21671136) and Shenzhen Science and Technology Project Program (JCYJ20180305125729925).