Multidimensional synergistic design of Co/halloysite/graphene oxide composites for broadband electromagnetic wave absorption

To address the problem of narrow bandwidth in conventional electromagnetic wave (EMW) absorbing materials, which severely limits their practical applications. We proposed an integrated strategy that combined microstructural regulation of multi-dimensional composites with macroscopic structural design. A ternary Co/HNTs/GO composite was fabricated, in which one-dimensional halloysite nanotubes (HNTs) acted as a lightweight framework, two-dimensional graphene oxide (GO) established a conductive network, and Co nanoparticles introduced magnetic loss. This multi-dimensional synergistic architecture enhanced interfacial polarization, conductive pathways, and magnetic loss. After calcination optimization, the composite achieved a minimum reflection loss (RL min ) of −57.52 dB with an effective absorption bandwidth (EAB) of 5.02 GHz. Moreover, the absorption frequency was tuned across 4–18 GHz by varying the sample thickness from 2 to 5 mm. In addition, a step-pyramid structure optimized by electromagnetic simulation further expanded the EAB to 12.4 GHz (5.6–18 GHz), fully covering the X and Ku bands. This integrated material-structure strategy provided a promising paradigm for the rational design of broadband and high-performance EMW absorbers.