Hierarchical porous carbon derived from green cyclodextrin metal‐organic framework and its application in microwave absorption

Abstract

γ‐cyclodextrin (CD)‐metal‐organic framework (MOF)‐K is developed as a new kind of green template for the preparation of hierarchical porous carbon (HPC). Three‐level porous structure (micro‐, meso‐, and macro‐pores) has been successful constructed by calcined γ‐CD‐MOF‐K at 600°C. The fabricated carbon (HPC‐600) shows good microwave adsorption ability due to its unique hierarchical porous structure (macropores allow microwave enter the interior of the absorbents, and then micro‐ and meso‐pores attenuate the incident microwave effectively by multiple reflections and polarization loss caused.) The minimum reflection loss (RL) is − 23.5 dB and the effective absorption bandwidth (EAB, RL≤− 10 dB) is 4.3 GHz. This work provides a good reference for efficient and environment‐friendly microwave absorbents. In addition, the applications of HPC‐600 may further expand to adsorption, sensing and supercapacitors due to the hierarchically porous structure.

State of the Art and Prospects in Metal-Organic Framework-Derived Microwave Absorption Materials

“…Furthermore, different pore sizes correspond to different microwave length, which indicates that the gradient distribution of pore structure is beneficial to broaden the EAB [ 149 ]. Besides, macropores can facilitate the impedance match of MAMs, while mesopores and micropores can enhance the multiple reflection of microwave inside the MAMs [ 109 ]. There are many approaches to construct MAMs with multiple pore sizes such as etching [ 176 ] and template method [ 42 ].…”

“…For instance, Zhang et al fabricated ingenious hierarchical porous carbon (HPC) materials using γ-CD-MOF-K as carbonizing template with K 2+ acted as activator in the formation of HPC (Fig. 8 g) [ 109 ]. The HPC-600 was obtained by directly pyrolyzing γ-CD-MOF-k at 600 °C, and the HPC-600-900 was fabricated by calcining HPC-600 at 900 °C subsequently.…”

Cyclodextrin metal–organic frameworks and derivatives: recent developments and applications

“…The few compounds synthesized until now have shown auspicious performance in isomer separation, agriculture, watertreatment, and microwave absorption. [69][70][71]172 3.3.1 Synthesis CD-MOF derived materials. The most common and important compounds derived from CD-MOFs are nanoporous carbon (NPC) materials.…”

“…Interestingly, it was found that the unique hierarchical structure of g-CD-MOF derived HPC endows it with microwave absorption abilities. 172 At first, the large number of macro-pores allows the electromagnetic waves to enter the interior of the structure due to the good impedance matching of the material. Then, the incident microwave can be effectively attenuated by multiple reflections and polarization loss in the micro-and meso-pores.…”

“…The few compounds synthesized until now have shown auspicious performance in isomer separation, agriculture, water-treatment, and microwave absorption. 69–71,172…”