Novel nanoporous carbon derived from metal-organic frameworks with tunable electromagnetic wave absorption capabilities

Nanoporous carbon materials derived from metal organic frameworks (MOFs) have attracted considerable attention due to their low density for microwave absorption. Nevertheless, their poor impedance matching has reduced the absorber performance. The design and fabrication of complex nanocarbon materials with outstanding impedance matching is still a challenge. Here, we prepared a core-shell structured ZIF-8@ZIF-67 crystal through a new seed-mediated growth method. After the thermal treatment of ZIF-8@ZIF-67 crystals, we obtained selectively nanoporous carbon materials consisting of ZnO/NPC as the cores and highly graphitic Co/NPC as the shells. The shell thicknesses of ZIF-67 can be tuned simply by varying the feeding molar ratios of Co2+/Zn2+. The composites exhibited excellent impedance matching and strong absorption. The composite ZnO/NPC@Co/NPC-0.5 samples filling with 50 wt% of paraffin show a maximum reflection loss (RL) of -28.8 dB at a thickness of 1.9 mm. In addition, a broad absorption bandwidth for RL <-10 dB which covers from 13.8-18 GHz can be obtained. Our study not only bridges diverse carbon-based materials with infinite metal-organic frameworks but also opens a new avenue for artificially designed nano-architectures with target functionalities.