MOFs derived flower-like nickel and carbon composites with controllable structure toward efficient microwave absorption

Controlling the structure of microwave absorption materials to ameliorate the microwave absorption performance is attracting extensive interest. Here, the flower-like nickel and carbon composites are fabricated by using metal organic frameworks (MOFs) as sacrificial precursors. By simply changing the conditions of the solvothermal reaction, the structure of flower-like Ni MOF precursors evolve from solid to yolk-shell and hollow. After annealed at 600 degrees C under Ar atmosphere, the resultant hollow flower-like nickel and carbon composite displays strongest reflection loss of -59.38 dB and the effective absorption bandwidth is 5.22 GHz at thickness of 3.0 mm. More importantly, the effective absorption bandwidth is as wide as 6.4 GHz at thickness of 2.4 mm. The synergistic effect of hollow and flower structure help to improve the polarization and stimulate the multiple reflections and scattering of electromagnetic waves. This work confirms that the design of microstructure is a promising route to moderate the microwave absorption performance.