The electromagnetic properties and microwave absorption of mesoporous carbon

Abstract

The electromagnetic properties and microwave absorption of a series of ordered mesoporous carbon from different carbonization temperatures are investigated. The degree of graphitization of mesoporous carbon is gradually increased with increasing carbonization temperature, leading to a sudden increase in complex permittivity and negative imaginary part of complex permeability. The microwave absorption behaviors calculated from measured complex permittivity and complex permeability suggest that the optimum sample, MC-650 (mesoporous carbon obtained at 650 °C), exhibits very strong reflection loss (−27.1 dB at 16.2 GHz) and wide response bandwidth (4.8–18 GHz over −10 dB) due to its well matched characteristic impedance and dielectric loss. By comparing the electromagnetic properties and microwave absorption of disordered mesoporous carbon and nonporous carbon materials, it can be concluded that the degree of graphitization is the primary factor affecting the microwave absorbing properties of carbon materials. In the case of a relatively high degree of graphitization, the carbon materials with different porous structure show very similar reflection losses. Only for the samples with the appropriate degree of graphitization, pore structure and degree of order will also play important roles, which can not only improve characteristic impedance, but also increase the reflection loss.