Excellent Electromagnetic Absorption Capability of Ni/Carbon Based Conductive and Magnetic Foams Synthesized via a Green One Pot Route

Abstract

Electromagnetic microwave absorption materials have attracted a great deal of attention. Foams for the low density and tunable porosity are considered as ideal microwave absorbents, while with the requirement of improving their inherent electromagnetic properties. In this manuscript, an innovative, easy, and green method was presented to synthesize an electromagnetic functionalized Ni/carbon foam, in which the formation of Ni nanoparticles and carbon occurred simultaneously from an affordable alginate/Ni(2+) foam precursor. The resultant Ni/carbon foam had a low density (0.1 g/cm(-3)) and high Ni nanoparticles loading (42 wt %). These Ni nanoparticles with a diameter of about 50-100 nm were highly crystallized and evenly embedded in porous graphite carbon without aggregation. Also, the resultant foam had a high surface area (451 m(2) g(-1)) and porosity and showed a moderate conductivity (6 S/m) and significant magnetism. Due to these special characteristics, the Ni/carbon foam exhibited greatly enhanced microwave absorption ability. Only with 10 wt % of functional fillers being used in the test template, the Ni/carbon foam based composite could reach an effective absorption bandwidth (below -10 dB) of 4.5 GHz and the minimum reflection value of -45 dB at 13.3 GHz with a thickness of 2 mm, while the traditional carbon foam and nano-Ni powder both showed very weak microwave absorption (the minimum reflection value < -10 dB). This foam was demonstrated to be a lightweight, high performance, and low filler loading microwave absorbing material. Furthermore, the detailed absorption mechanism of the foam was investigated. The result showed that the derived strong dielectric loss, including conductivity loss, interface polarization loss, weak magnetic loss, and naoporosity, contributes a great electromagnetic absorption.

Manganese and Zinc Spinel Ferrites Blended with Multi-Walled Carbon Nanotubes as Microwave Absorbing Materials

“…Small differences in permeability can even affect the microwave absorption properties of the materials [44]. It will be seen later that the magnetic characteristics contributed well to the RL values in Figure 12.…”

“…The space-charge polarization can contribute an extra relaxation, resulting in an increase of the dielectric loss to some degree [43]. For ferrite materials, it should be noted the value of ε′ is considerably bigger than that of µ′, which is related to loss tangent factors [44].…”

Capacitive deionization of NaCl solutions with ambient pressure dried carbon aerogel microsphere electrodes

“…The spectrum is subjected to peak tting using the soware Origin to resolve the curve into 2 Gaussian bands. 30,31 The tting results of the sample are given in Table 1.…”

“…The high ratio of mesoporosity can signicantly improve the desalination performance of the carbon-based electrode materials in CDI. 31 It is clear that the synthesized CA microspheres are propitious to the application of CDI as they have appropriate PSD and high available surface area. Therefore, the CA microspheres synthesized by emulsion polymerization and ambient drying may show great CDI performance when used as electrode material.…”

NaCl leached sustainable porous flexible Fe3O4 decorated RGO-polyaniline/PVDF composite for durable application against electromagnetic pollution

“…The electromagnetic (EM) waves emitted from ubiquitous sources of electronic gadgets or equipment and interacts with each other, creating serious Electromagnetic Interference (EMI) problems or EMI pollution that has negative influence on the human health, environmental pollution, and normal performance of electronic equipment [2]. In July 1967 it was claimed that 134 lives and electronics equipment (cost $72 million) were damaged due to undesirable interference from EM waves at the USS Forrestal off the coast of Vietnam [3].…”