Surface Architecture of Ni-Based Metal Organic Framework Hollow Spheres for Adjustable Microwave Absorption

Ni-based metal organic framework (MOF) hollow spheres were successfully synthesized by hydrothermal method. After carbonization in nitrogen at 600 ℃, a surface layer made of different Ni architectures are formed. The shape and size of the surface architectures (e.g. needles or pillars) can be adjusted effectively by controlling the duration of the hydrothermal reaction, leading to variable anisotropy and electromagnetic properties. The investigation of the microwave attenuation performance reveals that the paraffin wax composite (50 wt.%) of Ni-MOF with 8 hours and 10 hours reaction time could exhibit multiple resonance behavior in permeability curves due to different anisotropy of the magnetic Ni architectures on the surface and that in the shell of the hollow Ni-MOF spheres. Such multi-resonance behavior could also benefit the bandwidth of the Ni-MOF hollow sphere absorber. It is found that the 8 hours and 10 hours samples could reach a broad effective absorption bandwidth (EAB, RL< -10 dB) of about 6.8...