Graphene‐Based Composites Combining Both Excellent Terahertz Shielding and Stealth Performance

Strong terahertz‐response material which exhibits both excellent terahertz shielding and stealth performance is promising in practical applications of terahertz technology. Here, ultralight graphene foam (GF) and multiwalled carbon nanotubes/multiwalled graphene foam (MGF) have been first demonstrated to achieve both superior terahertz shielding and stealth performance due to the dominant absorption loss with negligible reflection. The terahertz shielding effectiveness values of GF and MGF, both 3 mm thick, reach up to 74 and 61 dB. Meanwhile, their average terahertz reflection loss values are achieved up to 23 and 30 dB, respectively, which are the best results in existing broadband terahertz shielding/stealth materials. Importantly, their qualified absorption bandwidths (reflection loss value larger than 10 dB) cover the entire measured frequency band of 0.1–1.6 THz. Furthermore, the quantitative relationships between the terahertz shielding effectiveness, reflection loss, and material parameters are accurately established, which should facilitate the material design for terahertz shielding and stealth. Comprehensively considering the important indicators of density, bandwidth, and intensity, the specific average terahertz shielding coefficient and the specific average terahertz absorption performance are achieved up to 1.1 × 105 and 3.6 × 104 dB cm3 g−1, respectively, which is over thousands of times larger than other kinds of materials reported previously. Graphene‐based composites combining both outstanding terahertz shielding and stealth performance are first demonstrated. The composites present maximum average shielding effectiveness of 74 dB and reflection loss value of 30 dB in the whole measured band due to the dominant absorption loss with negligible reflection (