Flower-like BiOI microsphere/Ni@C nanocapsule hybrid composites and their efficient microwave absorbing activity

At present, microwave absorbers are prepared by dispersing absorbing nanomaterials in a binder, which can lead to the aggregation of nanomaterials in the binder and further affect the optimization of the absorption performances. Hybrid micro/nano-scale structures are beneficial for buffering agglomeration phenomena and the construction of multiple interfaces. Here, Ni@C nanocapsules are conjugated onto flower-like BiOI microspheres, forming micro/nano-scale hybrid composites. The multiple interfaces between BiOI microspheres and Ni@C nanocapsules can bring enhanced dielectric loss and increased attenuation constant, resulting in the enhancement of absorption capacity (the optimal reflection loss reaches -61.35 dB), increased width of the effective absorption band (the maximum effective bandwidth, f(Emax), is 5.86 GHz) and the reduction of absorption thickness (the thickness corresponding to f(Emax) is 1.7 nun). This study highlights a simple idea for the optimization of electromagnetic absorbing performance, which is of great significance in the development of microwave absorbers.