Construction of a novel point-layer structure BNNSs/GQDs composites and research on the regulation of its microwave absorption performance by N and F-doped GQDs

To explore the improvement of microwave absorption performance of boron nitride nanosheets (BNNSs) after doping with graphene quantum dots (GQDs). Herein, a series of point-layer structure BNNSs supported by GQDs composite absorbing materials were designed and prepared. The influence of the substrate on the wave absorption intensity was investigated by loading the same GQDs with BNNSs of different scales. Among them, the BG-1400 with BNNSs-1400 as the substrate and GQDs as the load has the best microwave absorption performance. Its minimum reflection loss ( RL min ) reaches −60.3 dB and the effective absorption frequency band is 8.5 GHz. In order to further analyze the factors influencing the effective absorption frequency bands of BNNSs/GQDs composites, BNG-1400 and BFG-1400 were prepared by loading N-GQDs and F-GQDs respectively on the BNNSs-1400 substrate, and their RL min and effective absorption frequency bands were -57.3 dB, −57.7 dB and 11.3 GHz, 13.4 GHz, respectively. The effective absorption frequency bands of BNG-1400 and BFG-1400 have been significantly improved compared with BG-1400.This indicates that the substrate size of the BNNSs/GQDs composite material can control its absorption intensity, while different doped elements in GQDs can adjust its effective absorption frequency band. This discovery lays the foundation for the research on the controllable adjustment of the wave absorption performance of BNNSs/GQDs composite absorbing materials.