Hydrogel Infusion Additive Manufacturing of Customized Hierarchical Porous Cobalt/Carbon Composites for Electromagnetic Wave Absorption

Abstract

Magnetic-metal/carbon composites are crucial electromagnetic wave absorbing materials, of which both composition and structures critically determine the electromagnetic attenuation efficiency. However, achieving precise customization of such composites with hierarchical porous architectures still remains a significant challenge. Herein, we proposed a novel hydrogel infusion additive manufacturing strategy, assisted by subsequent microwave plasma-assisted reduction and pyrolysis, to fabricate structurally customized hierarchical porous cobalt/carbon composites. This integrated approach combined digital design with additive manufacturing to fabricate complex multiscale geometries unattainable by conventional methods, while the subsequent MPAR-CVD process preserved their structural integrity. Three distinct structural designs (teardrop, sprung and octet) were realized to demonstrate the feasibility of this strategy. Among them, the Co/C-octet composite exhibited exceptional performance, achieving a minimum reflection loss of -58.48 dB at 2.7 mm thickness and an effective absorption bandwidth of 4.48 GHz (10.64-15.12 GHz). The customized Co/C composites achieved exceptional electromagnetic wave absorption by leveraging a synergistic combination of their intrinsic dielectric-magnetic properties and a unique 3D hierarchical structure. This architecture extended the propagation path and promoted impedance matching. Theoretical simulations revealed that the 3D hierarchical configurations led to divergent interface and defect distributions, thereby effectively tailoring conductive and polarization losses for enhanced microwave attenuation. This work not only presented a high-performance EMW absorber but also offered a new pathway for designing structurally customized magnetic metal/carbon-based composites.