Toward dynamic tuning of 6G mid-band signals: synergistic interfacial polarization and confinement effects for precise electromagnetic attenuation.

The advancement of 6G communication technology demands electromagnetic wave (EMW) absorbers with both high performance and precise frequency tunability across the X (8-12 GHz) and Ku (12-18 GHz) bands. Herein, a Co-N/Co/C modified WPU composite derived from a metal-organic framework precursor is developed, which concurrently incorporates cobalt single atoms and cobalt nanoparticles. The resulting absorber exhibits an ultralow reflection loss of -64.0 dB at 14.4 GHz and a broad effective absorption bandwidth of 5.6 GHz, fully covering the Ku band with a low filler loading of 12.5 wt% and a thin thickness of 2.3 mm. To further tailor absorption toward the X band, two synergistic strategies are proposed. The first involves B/P co-doping to create asymmetric coordination sites for electronic confinement, while the second employs low-temperature pyrolysis to retain ZnO, which helps construct abundant heterointerfaces and boost interfacial polarization. By integrating atomic scale confinement with heterointerface engineering, this work offers a rational and versatile design pathway to lightweight, high performance EMW absorbing materials for next generation 6G applications.