Synergistically assembled MWCNT/graphene foam with highly efficient microwave absorption in both C and X bands

It is a great challenge to fabricate lightweight microwave absorption materials (MAMs) with strong electromagnetic wave attenuation over wide frequency range. In this work, ultralight multiwalled carbon nanotube (MWCNT)/graphene foams (CGFs) are prepared through a facile solvothermal method and their microwave absorption (MA) properties are fully investigated. The CGFs exhibit tunable complex permittivity and conductivity through regulating MWCNT loading and thermal reduction temperature. The addition of MWCNT remarkably enhances the MA intensity of CGFs in low frequency. A minimum reflection loss value of -39.5 dB and average absorption intensity exceeding 22.5 dB in both C (4-8 GHz) and X (8-12 GHz) bands are obtained. For the optimized CGF, the qualified bandwidth with reflection loss less than -10 dB reaches up to 16 GHz, which covers the whole measured range of 2-18 GHz and shares the widest qualified bandwidth among open literature reports. Furthermore, a specific MA performance of 12243 dB cm(2) g(-1) is realized, which is one of the best results among various MAMs. The synergistic effect of MWCNT and graphene and thus obtained three dimensional high loss multilevel network architecture are thought to be the primary causes for the excellent MA performance of CGFs. (C) 2017 Elsevier Ltd. All rights reserved.