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

ABSTRACT

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.