Porous core-shell zeolitic imidazolate framework-derived Co/NPC@ZnO-decorated reduced graphene oxide for lightweight and broadband electromagnetic wave absorber

High-efficiency microwave absorbers, characteristic of thin thickness, lightweight, broad bandwidth and strong absorptivity, have presented the immense potential in daily communication and radar stealth. Herein, a novel 3D heterostructured material with high specific surface area and high porosity, namely Co/NPC@ZnO/rGO, was constructed via a facile four-step method, in which porous core-shell Co/NPC@ZnO NPs with the diameter of around 700 nm prepared by the direct pyrolysis of ZIF-67@ZnO NPs were uniformly implanted onto and tightly wrapped in pleated rGO nanosheets. Benefiting from the well-designed components and configurations that can lead to the desirable impedance matching, occupying a crucial position in the entire absorption process; and the enhanced attenuation capacity derived from unique porous and core-shell architectures; the as-prepared composites evenly mixing the paraffin matrix with 30 wt% display the dramatically exceptional microwave absorbency, achieving the optimal reflection loss(RL) of -45.4 dB at thickness of only 2 mm, and especially, the valid response bandwidth of 5.4 GHz, when the mass percentage of Co/NPC@ZnO to GO is 3:1. Additionally, coupling with the merit of lightweight originating from the porous appearance of Co/NPC@ZnO and the inherent nature of rGO, this research exhibits the tremendous reference value for the assembly of ideal lightweight and wideband microwave absorbents in the future. (C) 2019 Published by Elsevier B.V.