具有宽频与可控微波吸收性能的石墨烯空心微球的自组装

Self-assembly of Graphene Hollow Microspheres with Wideband and Controllable Microwave Absorption Properties

用简单高效的两步法制备了一种包覆有四氧化三铁的还原石墨烯空心微球(Air@r GO€Fe_3O_4)。两步法包括油包水乳化技术和高温煅烧技术。Air@r GO€Fe_3O_4空心微球的介电损耗和磁损耗优异,使其具有良好的微波吸收性能。空心微球在石蜡中的添加量为33.3%、厚度为2.8 mm的微球在10 GHz处有最小反射率,为-52 d B,反射率小于-10 d B的频率范围为7.5~14.7 GHz。调节各成分的配比和样品厚度可控制空心微球的吸波性能。随着四氧化三铁含量的提高,微球的最小反射率的峰值位置向高频移动。Air@r GO€Fe_3O_4空心微球有吸收频率范围宽、吸收强度大以及吸波性能可调控等优点,使其成为具有潜在应用价值的高性能吸波材料。

Fe_3O_4 nanoparticles coated hollow microspheres of reduced graphene oxide（Air@r GO€Fe_3O_4） were synthesized via a simple and efficient two-step method consisting of water-in-oil（W/O）emulsion technique and subsequent annealing process. The Air@r GO €Fe_3O_4 hollow microspheres showed good electromagnetic properties because of the coexistence of magnetic loss and dielectric loss to microwave. The microwave absorbing bandwidth（reflection loss-10 d B） for Air@r GO€Fe_3O_4 of thickness in 2.8 mm（with 33.3 mass% paraffin） locates in the range of 7.5~14.7 GHz, while a minimum reflection loss-52 d B at 10.0 GHz. More interestingly, the microwave absorbing properties of the hollow microspheres can be easily controlled by tuning the ratio of the two components in the composites and the thickness of samples, and as the Fe_3O_4 content increase, the minimum reflection loss valve of Air@r GO€Fe_3O_4 microspheres move to higher frequency range. These Air@r GO€Fe_3O_4 hollow microspheres are great potential candidate as microwave absorbents due to their excellent properties such as wide absorbing frequency, strong absorption, low density and controllable absorbing properties.