Preparationof Heteroatom-Doped Mesoporous Hollow Carbonmicropheres and the Electromagnetic Wave Absorbing Properties

At present, the development of high-efficiency electromagnetic wave (EMW) absorbing materials has received close attention. Aiming at the problems of weak absorption strength and narrow frequency band of pure dielectric absorbing materials, poroushollow carbon microspheres (PCHM) with uniform mesoporous shells were prepared by a simple SiO₂ hard template method. Heteroatom-doped porous hollow carbon microspheres (Heteroatom-doped-PCHM) were prepared by controlling the doping mass ratios of PCHM to thiourea (1 : 5, 1 : 10, and 1 : 15), and the morphology, structure and electromagnetic wave absorption property of the samples were evaluated. The results show that when the doping mass ratio is 1 : 10, the prepared sample (Heteroatom-doped-PCHM-10) has a minimum reflection loss (RL_min) of –48.2 dB at the thickness of 3.0 mm, and a maximum effective absorption bandwidth (EAB_max) is 6.21 GHz at the thickness of 2.5 mm. Heteroatom-doped-PCHM-10 has the most suitable hollow cavity structure and the most suitable mesoporous structure. It has the controllable complex dielectric constant and a variety of attenuation mechanisms, including interface polarization, dipole polarization and conduction loss, and has excellent electromagnetic wave absorption property. Heteroatom-doped PCHM is characterized as a promising electromagnetic wave absorber with high absorption capacity, light weight and wide effective absorption bandwidth.