Facile preparation of ultralight porous carbon hollow nanoboxes for electromagnetic wave absorption

Strong absorption, thin thickness, low density and broad band are ideal characteristics of electromagnetic wave absorption (EWA) materials. In this work, ultralight porous carbon hollow nanoboxes (PCHN), which have low density and high specific surface area, are successfully prepared by the vapor deposition and etching process. Excellent EWA performances are achieved in the filler with only 3 wt%. A minimum reflection loss (RLmin)value of −30.46 dB (2.2 mm) along with an efficient absorption bandwidth (EAB) (RL ≤ −10 dB) of 5.44 GHz is achieved. And the EAB (RL ≤ −20 dB, corresponding to 99% absorption) can be tuned in the frequency band of 4.88–17.04 GHz via adjusting the thickness from 6.0 to 1.9 mm. The excellent EWA performance is attributed to conduction loss, interfacial polarization, and good impedance matching. Moreover, the adjacent carbon micro-sheets can provide multiple positions for EW reflection, which prolongs the propagation paths of EW and is conducive to the consumption of EW energy. The light weight, broad band and superior RLmin value make the as-prepared PCHN promising candidates for practical EWA applications.