Interfacial interactions and synergistic effect of CoNi nanocrystals and nitrogen-doped graphene in a composite microwave absorber

We reported a facile one-pot polyol route for the fabrication of CoNi/nitrogen-doped graphene hybrids as synergistic microwave absorber. Microstructure investigations suggest that all the CoNi nanocrystals are uniformly anchored on the nitrogen-doped graphene nanosheets without aggregation and the hybrids are stable under ultrasound treatment, which suggest that these nonvalent CoNi alloys are in-situ grown on nitrogen-doped graphene with a strong interaction. Taking both the synergistic benefits of magnetic CoNi nanocrystals and electric nitrogen-doped graphene, the CoNi/nitrogen-doped graphene hybrids show a maximum reflection loss of 22 dB at 10 GHz with a matching thickness of only 2.0 mm, and the effective absorption bandwidth with reflection loss exceeding 10 dB is 3.6-18 GHz with the absorber thickness of 1.35-5.0 mm. Compared with the single CoNi nanocrystals and graphene oxide, the CoNi/nitrogen-doped graphene hybrids show improved microwave absorption properties. These results indicate that the interface interactions and synergistic effect between the CoNi nanocrystals and nitrogen-doped graphene play a significant role on the enhancement of microwave absorption properties. This work suggests that the CoNi/nitrogen-doped graphene hybrids can be used as candidate materials for the design and manufacture of electronic nanodevices with high efficient microwave absorption properties. (C) 2016 Elsevier Ltd. All rights reserved.