Nitrogen-doped modified graphene aerogel enhancing interfacial bonding with lithium aluminium silicate ceramics for broadband microwave absorption

Abstract

The swift progression of e-communication technology has resulted in significant electromagnetic pollution, necessitating the urgent need for effective microwave-absorbing materials to mitigate this issue. Augmenting heterogeneous phase interfaces and incorporating heteroatoms constitute viable strategies for enhancing the electromagnetic properties of functional materials. In this study, a series of lithium aluminium silicate glass-ceramic/nitrogen-doped graphene (LAS/N-GF) aerogels was synthesised via the hydrothermal and freeze-drying methods. An innovative bonding mechanism for the heterogeneous phase interface was revealed, in which nitrogen doping enabled the formation of lattice defects in LAS ceramic particles and graphene and promoted a closed approach for unsaturated carbon and silicon atoms to form carbon-silicon bonds through the electrostatic force generated by interfacial polarization. Given that covalent bonds are widely recognized as stable carrier channels, the presence of carbon-silicon bonds at the interface facilitates electron migration, ultimately leading to improved microwave absorption. The maximum absorptivity of the LAS/N-GF aerogels could reach −47.98 dB at 8.96 GHz with a filler loading as low as 10 wt%. It is noteworthy that the LAS/N-GF aerogel exhibits an effective absorption bandwidth of 8.34 GHz, which fully spans the entire X-band and more than two-thirds of the Ku-band. Such exceptional performance is rarely observed in dielectric loss materials. Finally, the application potential of the LAS/N-GF aerogels in microwave absorbers was simulated and analysed. The unique chemical phenomenon stemming from the bonding at the carbon material-ceramic interface offers a fresh perspective in interface science, enabling a deeper comprehension of the underlying mechanism of microwave absorption.