Multi-dimensional nano-microstructures design of MOF-derived CoSe2@N-C composites toward excellent microwave absorption

Nano-microstructures design enabled the controlled tuning of electromagnetic parameters to obtain highperformance microwave absorption materials (MAM). Herein, Metal-Organic Frameworks-derived (MOFsderived) CoSe2@Nitrogen-doped Carbon (CoSe2@N-C) materials with controllable nano-microstructures also exhibit tunable morphologies from dodecahedra-, cube-, fusiform-to sheet-like by adjusting the solvent and the molar ratio of cobalt/ligand. The organic frameworks are maintained by pyrolysis selenization, forming a unique CoSe2@N-C three-dimensional conduction network that broadens electron transport and electromagnetic wave multiple reflection routes, enhances conduction loss capability, and optimizes impedance matching. The confinement of ligand-derived carbon can avoid the agglomeration of CoSe2, forming rich heterogeneous interfaces within CoSe2@N-C, enhancing interfacial polarization loss. Symmetric models are developed to reveal the importance of destructive interference on the microwave absorption property. In addition, dipole polarization of defects and doped-nitrogen further encourages the enhancement of the microwave absorption properties of CoSe2@N-C. The CoSe2@N-C-d exhibits the best microwave absorption properties with a minimum reflection loss (RLmin) of -42.31 dB at 15.62 GHz in a thickness of 1.5 mm, and an effective absorption bandwidth of 4.25 GHz. The excellent absorption performance of CoSe2@N-C paves the way for the design and synthesis of highperformance absorbers.