A facile and large-scale route to prepare nitrogen/oxygen (N/O) co-doped two-dimensional carbon nanomesh with excellent microwave absorption properties

Two-dimensional porous carbon materials have been considered good candidates for developing lightweight microwave absorbers because of their low density and tunable dielectric constant. However, large-scale synthesis, with precise control of the microstructure, by a simple method, remains is still a great challenging. Herein, a two-dimensional N/O co-doped carbon nanomesh (NOCN) was prepared via large-scale route by simple carbonization of analogue polyurea (PU) nanosheet consisted of p-phenyldiisocyanate and urea, and the graphitization degree, porous structure, sheet size and the heteroatom doping content could be easily adjusted by controlling carbonization temperature. Thus, the electromagnetic parameter and the corresponding microwave absorption can be regulated. When the carbonization temperature was 900 °C (NOCN-900), the obtained sample exhibited the best microwave absorption performance, and the reflection loss (RL) value was -54.2 dB with an effective absorption bandwidth (EAB) of 7.44 GHz at a thickness of 2.3 under fill loading of only 5 wt%. The facile and large-scale synthesis route combined with excellent performance makes NOCN-900 to be a great promising candidate for practical application.

Quadrangular cone carbon-constructed effective 3D network for a lightweight and broadband microwave absorbent

Quadrangular cone carbon-constructed 3D network shows an excellent broadband performance of 6.7 GHz at an ultra-low filler loading of only 1.04 wt%.

Recent progress of MOF-derived porous carbon materials for microwave absorption

Microwave absorbing materials (MAM) have attracted considerable attention over the years in stealth and information technologies. Metal–organic framework (MOF) with a unique microstructure and electronic state has become an attractive focus as self-sacrificing precursors of microwave absorbers. The MOF-derived porous carbon (PC) materials exhibit a high absorbing performance due to the stable three-dimensional structure and homogeneous distribution of metal particles. MOF-derived PC materials are promising for ideal MAM via tuning of the structure and composition, resulting in appropriate impedance matching and the synergistic effect between magnetic and dielectric loss. In this review, the MOF-derived PC materials and their basic absorption mechanisms (dielectric loss, magnetic loss and impedance matching) are introduced, as well as the characters of various MOF-derived PC materials. In addition, this review provides a comprehensive introduction and tabulates the recent progress based on the classification of the MOF-derived metallic state, such as pure PC (without reduced metals), mono-metal/PC, multi-metal/PC, metal oxides/PC and other derived PC composites. Finally, the challenges faced by MOF-derived PC materials are overviewed, and their further development is mentioned.

MOF-derived PC materials with unique characteristic have been widely concerned as microwave absorbers over the years.