Absorption-Dominated Electromagnetic Interference Shielding via Dual-Gradient Functionalized Carbon Nanotube Composites

Electromagnetic interference (EMI) shielding materials with high efficiency and absorption-dominated performance are crucial for addressing the challenges posed by electromagnetic wave pollution in modern electronics. In this work, we developed a high-performance EMI shielding material by integrating functionalized CNTs (f-CNTs) into a dual gradient conductivity–porosity structure. The multilayer structure was fabricated using a facile hot-pressing method, enabling the combination of films with varying porosity and conductivity. This approach facilitates the scalable production of large-area shielding materials and allows for the customization of EMI shielding properties by adjusting the layer characteristics. The resulting composite exhibited outstanding EMI shielding effectiveness (SE) of up to 60.5 dB across the X-band frequency range, with an absorptivity of approximately 0.77. The porosity gradient effectively minimized impedance mismatch, enhancing absorption and internal scattering, while the conductivity gradient promoted the dissipation of residual EM waves through Ohmic loss and interfacial polarization. These synergistic effects contributed to the absorption-dominant shielding mechanism. This study introduces a design and fabrication strategy for high-performance EMI shielding materials, combining gradient porosity and conductivity to achieve superior absorption and shielding efficiency. The proposed method offers a scalable and versatile approach for tailoring electromagnetic shielding materials.