High-Performance Electromagnetic Wave Absorbers Based on Two Kinds of Nickel-Based MOF-Derived Ni@C Microspheres

Abstract

Metal–organic framework (MOF)-derived composites on the microwave absorption have received extensive attention. However, which kind of organic ligand corresponding MOF derivative has better electromagnetic wave absorption performance is an urgent problem to be solved. In this work, two kinds of Ni@C derived from the Ni-based MOFs with two kinds of organic ligands (dimethylimidazole as a ligand named as Ni-ZIF and trimesic acid as a ligand named as Ni-BTC) were successfully obtained. The compositions, morphologies, and electromagnetic properties of two composites were well controlled. As a result, both kinds of Ni@C exhibited the good microwave absorption properties. Comparatively speaking, the Ni@C derived from Ni-ZIF performs better. The Ni@C-ZIF microspheres with a 40% mass filling ratio exhibited a strong reflection loss of −86.8 dB at 13.2 GHz when the matching thickness was 2.7 mm, and the corresponding effective absorption bandwidth was 7.4 GHz (4–11.4 GHz) with the thickness ranging from 1.5 to 4.0 mm. The impedance matching, multiple reflection, and interfacial polarization among Ni and C were beneficial to the enhancement of microwave attenuation, which N-doping introduced by nitrogen-containing ligands leads to excellent microwave absorption properties. Therefore, this work can give insights into understanding the absorbing mechanism as well as provide a simple and flexible paradigm for the design and synthesis of the absorber with the tunable and high-efficiency performances.

Synthesis of Controllable Nickel Chalcogenide Nano‐Hollow Spheres and Their Tunable Absorbing Properties

“…Thus, the theoretical reflection loss (RL) values of nickel chalcogenide hollow spheres with different filler loadings at various thicknesses can be obtained through Equations (1) and (2). Figure 5 shows the calculated theoretical RLs of the nickel chalcogenide hollow spheres-paraffin composites with different thicknesses (2-5 mm) in the range of 2-18 GHz with a loading of 20 wt%.…”

“…In recent years, with the wide application of electronic products, serious environmental pollution has been generated owing to a large amount of electromagnetic radiation, which has bringing great harm to human life. [1][2][3][4] It is urgent time to solve the problem of electromagnetic wave pollution. At present, both electromagnetic shielding and electromagnetic wave absorbing materials are available to mitigate electromagnetic interference.…”

Nickel Carbon Composite With Carbon Nanotubes for Efficient Electromagnetic Wave Absorption

“…In Fig. 5(d), the XPS spectrum of Ni 2p displays two shake-up satellites and two primary peaks at the binding energy of 854.08 and 871.25 eV, corresponding to the Ni 2p 3/2 and Ni 2p 1/2 for metallic Ni, respectively [16,37].…”

“…Wang and co-workers [15] used Co-MOF-74 as the precursor to fabricate porous Co-C core-shell nanocomposites with RL max of -62.12 dB at 11.85 GHz. Ni/C composite prepared by pyrolyzed nickel based MOF at high temperatures showed a strong RL of -86.8 dB at the thickness of 2.7 mm [16]. Nevertheless, for MOFs derived metal/carbon composites, it is still di cult to achieve excellent EM wave absorption performances with low-thickness regions and broad effective absorption bandwidth (EAB).…”

High‐performance N, P‐CNL nanocomposites as catalyst for oxygen reduction reaction in fuel cell

“…Transition metal/heteroatom-doped carbon materials (MNCs) have become the most promising alternative to replace commercial platinum carbon (Pt/C) catalysts due to their low cost, wide range of raw materials, high activity, high stability, and resistance to methanol. 17,18 The combination of transition metal salts and nitrogen-doped carbon materials (such as nitrogen-doped carbon nanotubes, 5,[19][20][21][22] nitrogen-doped carbon nanofibers, 23,24 nitrogen-doped carbon spheres, [25][26][27][28] nitrogen-doped graphene, 13,[29][30][31][32][33] etc.) display superior performance according to the current research.…”