NiCo@NPC@CF nanocomposites derived from NiCo-MOF/cotton for high-performance electromagnetic wave absorption

Abstract

Electromagnetic (EM) wave absorption materials with a light weight and low-cost are in urgent need, because of the increasing radiation interference and pollution by EM. Although a large number of carbon materials have been explored as EM wave absorbers, most of them exhibit a quite limited EM wave absorption performance because of their unstable structure, low permittivity and poor impedance matching. To overcome this limitation, a series of NiCo@nanoporous carbon@carbon fiber nanocomposites (NiCo@NPC@CF-x, x = 600, 700 or 800) composed of a micro-to-nano hierarchical porous carbon structure and flower-like NiCo@C particles using Ni/Co-MOF particles and biomass cotton as precursors, are fabricated. Benefiting from the participation of biomass cotton, the minimum reflection loss (RL_min) of hierarchical NiCo@NPC@CF is dramatically enhanced to −46.5 dB with a wide effective absorption bandwidth (EAB) of 10.0 GHz at a thickness of 3.5 mm. The total shielding effectiveness (SE_T) value of NiCo@NPC@CF-800 is 30.58 dB, suggesting that the sample is sufficient to shield more than 99.99% of incident EM waves. The carbonized 1D CFs facilitated the microwave energy dissipated by electron transportation and improved the impedance matching. The improvement of the wave absorption capacity was mainly attributed to the synergistic effect of the hierarchical pore structure, better impedance matching and a larger attenuation constant. Therefore, this work provides a feasible strategy to design and synthesize excellent EM wave absorbers and shielding materials by using the combination of MOFs and biomass materials as precursors.