Electrochemically Mediated Interfacial Charge Polarization in Heterostructured Flexible Films for Dynamic Electromagnetism Regulation

ABSTRACT Tunable electromagnetic waves (EMWs) response and dynamic regulation play a critical role in fields such as radar and satellite communication, ranging from radiation protection to signal compatibility. However, the modulation capability and thin‐film development of current electromagnetic materials are limited in the integration development in an effective dynamic electromagnetic environment, owing to their conductivity‐dominated single response mechanism. Unlike the previously reported conductivity‐dominant mechanism, this work proposes a design strategy based on H + ‐induced electron‐interface cooperative regulation by constructing an ultrathin acetylene black/H x WO 3 (AB/H x WO 3 ) heterostructure film device for real‐time electromagnetic wave modulation. Specifically, the controllable transformation of H x WO 3 from the initial monoclinic phase to the tetragonal phase and eventually to the cubic phase driven by H + insertion triggers the valence state evolution from W 6+ to W 4+ and the reduction of the work function, which significantly enhances the n ‐type doping effect and promoting the increase in free electron density, thereby achieving tunable EMWs reflective shielding efficiency (SE R : 3.7 to 6.0 dB). Meanwhile, the introduction of AB leads to the reconstruction of the energy band structure during the protonation of WO 3 , inducing strong polarization domains and a mass of dipoles at the AB/H x WO 3 heterointerface, which significantly enhances the polarization loss capacity and thereby promotes significant modulation in EMWs absorption shielding efficiency (SE A : 9.9 to 18.0 dB). Based on the above electron density and interface polarization synergistic enhancement mechanism, the AB/H x WO 3 electrode with a thickness of only 80.16 µm achieves significant modulation of the total shielding efficiency from 13.6 to 24.0 dB in X‐band and obtains an exceptionally large thickness‐normalized specific shielding efficiency (ΔSSE T ) of 130 dB mm −1 , significantly outperforming previous reports. These findings underscore the great potential of this lightweight, ultrathin device for integrated electronics and adaptive electromagnetic environment applications.