3D porous nickel metal foam/polyaniline heterostructure with excellent electromagnetic interference shielding capability and superior absorption based on pre-constructed macroscopic conductive framework

Abstract

The integration of dielectric and magnetic components is a promising strategy for fabricating electromagnetic interference shielding materials with peculiar characteristics. To further promote the shielding capability while still maintaining the high absorption performance, rational and meticulous structural design is urgently required for their practical application as advanced shielding materials. In this work, a highly porous nickel metal foam (NF) with the macroscopic pre-constructed conductive framework is selected as the substrate. Then, the polyaniline (PANI) coating layer is successfully intertwined on NF by a facile in-situ polymerization technology. Finally, the NF/PANI composite foam (NPF) with a unique three-dimensional (3D) porous heterostructure is created. Although the thickness is only increased by 2.7% of the pristine NF, the shielding effectiveness of NPF heterostructure is significantly improved, even reaching 93.8 dB (~99.99999996% radiation can be shielded). In particular, NPF possesses superior characteristics of absorption loss per unit thickness (147.64 dB/mm) among previously reported shielding materials. Such extraordinary performance could be ascribed to the 3D porous heterostructure, the presence of abundant interfaces, and dielectric-magnetic integration in NPF. These characteristics dramatically improve the interfacial polarization, dielectric polarization, dipole relaxation, attenuation constant, and multiple reflection. Both power balance analysis and the comparison between the absorption and reflection behaviors suggest that absorption dominates the shielding mechanism. The excellent comprehensive shielding capability endows such heterostructure with great application prospects in electronic devices. Furthermore, a prototype for achieving high-performance shielding materials based on 3D porous heterostructure is also provided.