Construction of 0D/2D heterojunction in 3D MXene/GQDs hybrid aerogels for enhanced broad electromagnetic wave absorption

Significant efforts have been made towards designing and fabricating MXene/carbon hybrid aerogels for electromagnetic wave (EMW) absorption applications. Carbon nano-species, such as 2D graphene and 1D carbon nanotubes (CNTs), have been widely incorporated into MXene/carbon aerogels. However, they often exhibit poor impedance matching due to their high conductivity, thus limiting further improvements in EMW absorption performance. Unlike 2D graphene and 1D CNTs/nanofibers, graphene quantum dots (GQDs) exhibit intriguing chemical and physical properties, as well as a zero-band electronic structure. To the best of our knowledge, the EMW response behavior of 0D/2D MXene/GQDs heterojunction in 3D aerogels has not yet been explored. Herein, we develop a unique approach for the controlled synthesis of 3D MXene/GQDs composite aerogels featuring with abundant 0D/2D heterojunctions. It was found that GQDs have a significant effect on the microstructure of MXene/GQDs aerogels. As the amount of GQD increases, more developed porous structures in aerogels are formed. The introduction of GQDs leads to the formation of numerous 0D/2D heterointerfaces and plays a key role in modulating the electromagnetic (EM) parameters and optimizing the impedance matching of 3D MXene/GQDs aerogels, thereby enhancing their absorption capabilities. The obtained MXene/GQDs aerogels exhibit a remarkable EMW response behavior, with a strong minimum reflection loss (RLmin) of -53.21 dB and a broad effective absorption bandwidth (EAB) of 7.90 GHz at 2.5 mm. The multiple dissipation modes and optimized impedance matching significantly contribute to the enhanced EMW absorption capabilities. This investigation offers a new boulevard for developing advanced 3D MXene-based hybrid aerogels beyond EM response.