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

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.