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

Electromagnetic microwave absorption materials have attracted a great deal of attention. Foams for the low density and tunable porosity, are considered as an ideal microwave absorbents, while with requirement of improving their inherent electromagnetic property. 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/Ni2+ 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 m2 g-1) and porosity and showed a moderate conductivity (6 S/m) and significant magnetism. Due to these special characters, 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 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 as a light weight, 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 together contribute a great electromagnetic absorption.