Cornstalk-derived macroporous carbon materials with enhanced microwave absorption
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Cornstalk-derived macroporous carbon materials with enhanced microwave absorption Jinfeng Li1, Nan Zhang1, Hongtao Zhao1,*, Zhigang Li1, Bo Tian1, and Yunchen Du2,*
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Institute of Technical Physics, Heilongjiang Academy of Science, Harbin 150009, China MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
Received: 31 July 2020
ABSTRACT
Accepted: 29 September 2020
Biomass transformation is being considered as a green and sustainable strategy for carbon-based functional materials in many fields. To produce porous structure favorable for microwave absorption, we demonstrate herein the successful synthesis of macroporous carbon materials with cornstalk as a biomass precursor. It is found that two kinds of typical biological structures in cornstalk, linear vascular bundles and parenchyma cells, can be well preserved during high-temperature pyrolysis. Mercury intrusion porosimetry and N2 adsorption indicate that these cornstalk-derived carbon materials have very high porosity, which is mainly from desirable macroporous structure rather than conventional micro/mesopores. Electromagnetic (EM) analysis reveals that dielectric loss is the only pathway for the consumption of EM energy, and high pyrolysis temperature favors strong dielectric loss through conductive loss and interfacial polarization loss. Meanwhile, pyrolysis temperature also affects the matching degree of characteristic impedance. When the pyrolysis temperature reaches 750 °C, good dielectric loss and impedance matching endow the sample (CSC750) with excellent microwave absorption performance, including strong reflection loss, broad response bandwidth, and relatively thin absorber thickness. The advantages of macroporous structure are further highlighted in impedance matching and multiple reflection by comparing with a macroporefree counterpart.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Jinfeng Li and Nan Zhang contribute equally to this work.
Address correspondence to E-mail: [email protected]; [email protected]
https://doi.org/10.1007/s10854-020-04571-5
J Mater Sci: Mater Electron
1 Introduction Microwave absorption is emerging as a promising strategy for the precaution of electromagnetic (EM) pollution, because it provides a more sustainable pathway to fundamentally eliminate incident EM waves as compared with conventional shielding strategy [1–3]. As a medium for energy dissipation, microwave absorbing materials (MAMs) can convert EM energy into heat or energy in other forms, and determine the efficiency of EM attenuation to a great extent [4, 5]. Magnetic materials, especially magnetic metals, were used to be typical MAMs in the past decades, whereas some intrinsic drawbacks, such as high density, easy corrosion, and low Curie temperature, make them incapable of being the next generation of MAMs [6, 7]. Carbon materials, e.g., carbon nanotubes (CNTs), carbon nanofiber
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