Co/C Composite Derived from a Newly Constructed Metal–Organic Framework for Effective Microwave Absorption

Abstract

The discovery of efficient electromagnetic wave absorbing materials for solving serious electromagnetic wave pollution is an urgent task. By rational design and assembly, a new three-dimensional metal–organic framework (MOF, CPT-1-Co) with the Co ions was constructed and employed as the precursor for the fabrication of Co/C composites via pyrolysis at high temperatures. The resultant Co/C composite pyrolyzed at 700 °C can absorb more than 90% of an EM wave at 2–18 GHz by the alternation of fabrication thickness. The effective absorption bandwidth can reach as high as 5.4 GHz at a thin thickness of 1.7 mm, which is superior to that of most EM wave absorbers. The bottom-up protocol in this report represents the first attempt to pyrolyze a new MOF for microwave absorber fabrication, which will provide valuable insight for designing more advanced MOFs and their applications in efficient electromagnetic wave absorption.

Electromagnetic wave absorbing properties of glucose‐derived carbon‐rich SiOC ceramics annealed at different temperatures

“…[37][38][39][40][41][42] It is obvious that the SiOC ceramics have the relatively weak electromagnetic wave absorption capability. [37][38][39][40][41][42] It is obvious that the SiOC ceramics have the relatively weak electromagnetic wave absorption capability.…”

Enhanced electromagnetic wave absorbing properties of Si‐O‐C ceramics with in‐situ formed 1D nanostructures

“…ε r and µ r are the measured relative complex permittivity and permeability, respectively. [34][35][36] For EMW absorbing material, a wide effective absorbing band is more important than a low RL. 12 EMW absorbing properties of various PDCs with and without catalysts pyrolyzed at different temperatures are concluded in Figure 9.…”

“…derived from different precursors pyrolyzed with the presence or absence of catalyst, 1,6,9,10,13,14,16,17,20,[27][28][29][30][31][32][33] the metal-loaded carbon material as a kind of wave absorbing filler incorporated into the pyrolyzed matrix with low conductivity also presents excellent wave absorbing properties, such as Co and Fe 3 O 4 . [34][35][36] For EMW absorbing material, a wide effective absorbing band is more important than a low RL. Compared with the recently reported polymer-derived Si-O-C absorbers, the catalytically pyrolyzed Si-O-C at 1500°C in this work without any additive filler achieves wider and lower absorbing band and RL in X band .…”

Enhanced electromagnetic wave absorption of Fe‐doped silicon oxycarbide nanocomposites

“…Nowadays, with the rapid development of the radar technology, wearable electronic products and wireless communication, the electromagnetic radiation and interface have already caused serious electromagnetic pollution, as well as military stealth technology . Despite numerous works have focused on electromagnetic interface (EMI) shielding materials, the ideal EMI shielding materials with lightweight, high flexibility, thermally and chemically stable with high‐efficiency over a broad absorption frequency range are still deemed for engineering . To achieve such ideal goal, the electromagnetic wave consumed by dielectric loss, magnetic loss and other energy loss mechanisms should be further enhanced .…”

“…[1][2][3][4][5] Despite numerous works have focused on electromagnetic interface (EMI) shielding materials, the ideal EMI shielding materials with lightweight, high flexibility, thermally and chemically stable with high-efficiency over a broad absorption frequency range are still deemed for engineering. [6][7][8] To achieve such ideal goal, the electromagnetic wave consumed by dielectric loss, magnetic loss and other energy loss mechanisms should be further enhanced. 9,10 Several categories of dielectric materials, such as graphene, [11][12][13][14] carbon nanotubes (CNTs), [15][16][17][18][19] and conducting polymers 20,21 can be considered as an excellent absorption material for the sake of large dielectric loss tangent.…”