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Liu L.,North China Electrical Power University | Bian X.-M.,North China Electrical Power University | Hou Z.-L.,Beijing University of Chemical Technology | Wang C.-Y.,Third Institution of China Aerospace Science and Industry | And 4 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2016

To understand the principles and mechanisms of the graphene-based electromagnetic response composites, we prepare magnetic graphene–Fe3O4 (G–F) hybrid materials and study the electromagnetic properties in the frequency region of 2–18 GHz. The introduction of Fe3O4 nanoparticles is found to play a dominant role in the complex permittivity, resulting in changing the surface polarization and interfacial resistivity of the graphene-based fillers. These influences have been found to greatly impact the corresponding microwave absorption and electromagnetic shielding performance. Owing to the syngeneic effects of G and Fe3O4, the wax-based composites with G–F presented effective microwave absorption (<−10 dB) and sufficient electromagnetic shielding performance (>20 dB) in the investigated region. The associated mechanisms based on tuning the electromagnetic response of the graphene-based composites via the unique Fe3O4 interfaces have been intensively discussed, which promises great guidance in rationally designing and fabricating advanced graphene-based electromagnetic response materials. © 2015, Springer Science+Business Media New York. Source


Song W.-L.,University of Science and Technology Beijing | Wang J.,University of Science and Technology Beijing | Fan L.-Z.,University of Science and Technology Beijing | Li Y.,Beijing Institute of Technology | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2014

Lightweight carbon materials of effective electromagnetic interference (EMI) shielding have attracted increasing interest because of rapid development of smart communication devices. To meet the requirement in portable electronic devices, flexible shielding materials with ultrathin characteristic have been pursued for this purpose. In this work, we demonstrated a facile strategy for scalable fabrication of flexible all-carbon networks, where the insulting polymeric frames and interfaces have been well eliminated. Microscopically, a novel carbon nanofiber-graphene nanosheet-carbon nanofiber (CNF-GN-CNF) heterojunction, which plays the dominant role as the interfacial modifier, has been observed in the as-fabricated networks. With the presence of CNF-GN-CNF heterojunctions, the all-carbon networks exhibit much increased electrical properties, resulting in the great enhancement of EMI shielding performance. The related mechanism for engineering the CNF interfaces based on the CNF-GN-CNF heterojunctions has been discussed. Implication of the results suggests that the lightweight all-carbon networks, whose thickness and density are much smaller than other graphene/polymer composites, present more promising potential as thin shielding materials in flexible portable electronics. © 2014 American Chemical Society. Source


Song W.-L.,University of Science and Technology Beijing | Guan X.-T.,University of Science and Technology Beijing | Fan L.-Z.,University of Science and Technology Beijing | Cao W.-Q.,Beijing Institute of Technology | And 3 more authors.
Materials Research Bulletin | Year: 2015

Graphene oxides (GO) have been widely utilized for preparing conductive heterostructures via converting insulating GO back to conductive reduced GO (RGO). Such conversion may substantially impact the results if the introduced heterostructures are sensitive to the conversion processes. To avoid the concerns, herein a novel Fe3O4/graphene (Fe3O4/GN) heterostructure of high electrical conductivity have been prepared by directly using highly conductive GN without any reducing agent or post-treatment. Results of the electrical properties, magnetic properties, complex permittivity and permeability suggest that the Fe3O4/GN interfaces are responsible for the influence of the corresponding properties. The intrinsically conductive features coupled with the Fe3O4/GN interfaces allow the heterostructures to possess sufficient microwave absorption at relatively low filler loading, with tunable effective absorption bandwidth observed over 4-18 GHz. Fundamental mechanisms indicate the advantages of the simple strategies and resulting heterostructures promise a great arena for advanced graphene heterostructures that are not achievable upon RGO. © 2015 Elsevier Ltd. All rights reserved. Source


Song W.-L.,University of Science and Technology Beijing | Guan X.-T.,University of Science and Technology Beijing | Fan L.-Z.,University of Science and Technology Beijing | Cao W.-Q.,Beijing Institute of Technology | And 2 more authors.
Carbon | Year: 2015

For extending graphene aerogels for broad applications, here we demonstrate a simple and universal approach for scalable fabricating novel dual carbon three-dimensional (3D) hybrid structures, where the interspace of a 3D carbon texture has been modified by in situ generating graphene aerogels. Owing to the unique exceptional 3D carbon bi-frameworks of enhanced electrical conductivity and flexibility, the as-prepared graphene aerogel-carbon texture hybrid presents an ultra-light feature (0.07 g cm-3 in density), with highly effective electromagnetic interference (EMI) shielding performance up to 27 dB and 37 dB (in the X band region) at thicknesses of 2 and 3 mm, respectively. According to the mechanisms in EMI shielding, the fundamental criteria for evaluating a shielding material has been discussed and the excellent shielding performance coupled with the ultra-low density allows such 3D all-carbon hybrids to show more advantageous than the other carbon-based shielding composites. Implication of the results suggests that the strategy of various advantages could be widely extended to a variety of applications, promising a great platform for large-scale fabricating porous graphene-based materials into high-performance products. © 2015 Elsevier Ltd.All rights reserved. Source


Liu L.,North China Electrical Power University | Bian X.-M.,North China Electrical Power University | Hou Z.-L.,Beijing University of Chemical Technology | Zhu J.-Y.,North China Electrical Power University | And 2 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2016

In this work, silica template was utilized into the phenol resin to fabricate a novel nanoscale polygonal carbon (NPC) toward effective microwave absorption fillers. The as-prepared NPC with polygonal features presents substantial improvement in the complex permittivity of the wax-based composites. The porous structure coupled with electrical conduction and polygonal characteristic enables the NPC to form an effective electrical loss network via the formation of unique 3D pathways. Therefore, the composite embedded with NPC delivers strong microwave absorption up to −38 dB at a low filler loading of 3 wt%, with a much broadened effective absorption bandwidth in the range of 7–13 GHz. In addition, the fundamental mechanisms of the complex permittivity and broadened effective absorption bandwidth have been intensively discussed, indicating more advantages in comparison with some graphene- or carbon nanotube-based fillers. The results suggest that the exclusive performance induced by the NPC promises great potential in the achievement of advanced microwave absorption composites with low-loading fillers. © 2016 Springer Science+Business Media New York Source

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