Metal-organic frameworks self-templated cubic hollow Co/N/C@MnO2 composites for electromagnetic wave absorption

Green and facile strategies for fabricating hollow microwave absorption materials without harmful solvent etching have attracted extensive attention but still remain a challenge. Herein, the cubic hollow Co/N/C@MnO2 composites were prepared through metal-organic frameworks (MOFs) self-templated eco-friendly method with polydopamine (PDA) as carbon source and hierarchical MnO2 nanosheets were incorporated for improving impedance mismatch caused by excessive permittivity in Co/N/C. Such a uniform distribution of Co particles in the N-doped porous carbon matrix, in association with the hollow structure and hierarchical MnO2 nanosheets, endow the composites with enhanced electromagnetic (EM) wave absorption. Notably, Co/N/C@MnO2 sample with a filler loading of 15 wt% shows extraordinary EM wave absorbing performance with the minimum reflection loss (RL) of -58.9 dB and wide absorption bandwidth of 5.5 GHz. Several minimum RL values at a thickness in the range of 1.5-5 mm, are below than -50 dB, outperforming many similar materials reported previously. Besides, the possible microwave absorption mechanism was elaborated in detail. Our work provides an environmentally friendly and facile route for fabricating MOFs self-templated hollow carbon-based microwave absorbers. (C) 2019 Elsevier Ltd. All rights reserved.