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.