High-performance microwave absorption of 3D Bi2Te2.7Se0.3/Graphene foam

Graphene foam (GF) has grabbed considerable attention for microwave absorption (MA) due to its high specific surface area, rich micro-nano structures and versatile processing. However, restricted by the intrinsic electromagnetic properties of graphene, the MA property of GF is usually unsatisfactory. To further improve the absorption strength of GF, groundbreakingly, the thermoelectric material Bi2Te2.7Se0.3 (BTS) and graphene are combined to form Bi2Te2.7Se0.3/GF (BTSGF) composites through a solvothermal self-assembly method. BTSGF composites have achieved much enhanced MA properties. The minimal reflection loss (RLmin) and the qualified absorption bandwidth of BTS9GF-200 (90 wt% BTS, annealed at 200 °C) reaches improved −73.0 dB and 5.32 GHz, respectively. Meanwhile, BTS3GF-300 (30 wt% BTS, annealed at 300 °C) exhibits an impressive qualified absorption bandwidth of 8.9 GHz and achieves an enhanced RLmin of −58 dB. The enhanced MA performance of BTSGF stems from various synergistic effects of BTS and GF, such as conduction loss and polarization. More importantly, BTS's thermal energy-electric energy conversion capability is believed to can quickly convert heat into electricity and strengthen the attenuation of electromagnetic waves. Therefore, a new electromagnetic wave-thermo-electric loss MA mechanism is proposed, which is of great significance to the study of thermoelectric materials as high-efficiency MA materials. Bismuth telluride/graphene foams (BTSGFs) are prepared using a facile solvothermal self-assembly method, followed by adjusting BTS loadings and annealing temperatures. The minimal reflection loss (RLmin) and the qualified bandwidth (reflection loss less than −10 dB) of BTS9GF-200 achieve −73.0 dB as well as 5.32 GHz, respectively. In addition, the RLmin of BTS3GF-300 achieves −58 dB and the qualified bandwidth reaches to 8.9 GHz. Besides, the mechanism for the BTSGFs performances dependence on the BTS contents and annealing temperatures of the BTSGFs is revealed. It is the first time to utilize Bismuth telluride as a microwave absorbing material that broaden the ranges of absorbing materials. [Display omitted]