Graphene Aerogels With Spherical Pore Structure for Broad Frequency Regulation and Enhanced Low-Frequency Response

Conventional microwave absorbers, with their fixed operating frequencies and narrow bandwidths, are fundamentally limited in the face of advancing multifrequency radar systems. Strain tuning is highly favored as a dynamic regulation strategy because of its simple operation and rapid response. However, achieving broadband tunability and strong low-frequency absorption in strain-tunable microwave absorbers remains challenging, as even slight compression can lead to significant increases in conductivity. Herein, we develop a spherical-pore-structured graphene aerogel (SPGA) through a microbubble-templating method. The spherical-pore topology effectively suppresses strain-induced percolation of conductive networks, rendering the electrical conductivity only weakly dependent on strain. SPGA achieves dynamic frequency tuning across 3.6-18 GHz while maintaining strong absorption under compressive strains of up to 70%. Simultaneously, it delivers enhanced low-frequency absorption with an effective absorption bandwidth of 2.56 GHz, spanning 91% of the low-frequency microwave spectrum. These results demonstrate the potential of topology-guided structural design for strain-tunable microwave absorption and suggest a viable route for the rational design of intelligent microwave absorbers.