In Situ Fabrication of Magnetic and Hierarchically Porous Carbon Films for Efficient Electromagnetic Wave Shielding and Absorption

Abstract

Carbon-based materials have been recognized as a promising method to eliminate electromagnetic interference (EMI) shielding and electromagnetic (EM) wave absorption. However, developing lightweight, ultrathin, and efficient EM wave-shielding and wave-absorbing materials remains a challenge. Herein, a series of magnetic porous carbon composite films with a hierarchical network structure were fabricated via pyrolysis of porous polyimide (PI) films containing magnetic metallic salts of Fe­(acac)3 and Ni­(acac)2. After pyrolysis, the obtained uniform porous carbon films (CFs) possess a favorable EMI-shielding efficiency (SE) of 46 dB in the X-band with a thickness of ∼0.3 mm. In addition, a higher EMI SE of 58 dB can be achieved by increasing the thickness of the porous CF-20Ni to 0.53 mm. Moreover, the CF-20Ni composites also present effective EM wave-absorbing performance of RLmin = – 30.2 dB with a loading amount of 20 wt % at 13.0 GHz owing to the hierarchically conductive carbon skeleton, magnetic Ni nanoparticles, and dielectric interlaced carbon nanotube cluster within the micropores. These novel lightweight and ultrathin porous CFs are expected to be attractive candidates for efficient EM wave absorption and EMI shielding.

Atomic Structure and Binding of Carbon Atoms

“…A structural and electrical relationship establish between amorphous carbon and graphene in deposited carbon films by hot filament CVD [41]. A recent study investigates porous carbon films for efficient electromagnetic applications [42]. Vertical mesoporous carbon films were investigated by studying their electrochemical sensors application [43].…”

Flexible Polypyrrole-Coated Polyamide Based Mats for Broadband Microwave Absorption and Electromagnetic Interference Shielding with Low Reflection

“…39,40 Among them, carbon aerogels have aroused a wide interest due to their 3D pore structure, continuous conductive matrix, low density, and electrical conductivity. 41,42 In addition, two-dimensional transition metal (MXene) films have also received broad attention in recent years due to their extraordinary conductivity (5.8 × 10 4 S•m −1 ), 43 which could turn out over 60 dB EMI SE for foam and textiles. 44−46 For example, Zong et al reported that MXene-derived titanium carbon nanotubes (CNT) and cellulose-derived carbon aerogels were prepared by grafting, freeze-drying, and pyrolysing, which achieves an efficient EMI shielding effect of 72.9 dB.…”

“…The EM shielding and absorbing ability of composite materials can be effectively enhanced by adjusting the distribution of their conductive components and structures. − Hence, it is an effective strategy to reduce the impedance mismatch by constructing a porous conductive network to reduce R and SE R values, such as conductive air gel, foam, and 3D braided fabric. , Among them, carbon aerogels have aroused a wide interest due to their 3D pore structure, continuous conductive matrix, low density, and electrical conductivity. , In addition, two-dimensional transition metal (MXene) films have also received broad attention in recent years due to their extraordinary conductivity (5.8 × 10 4 S·m –1 ), which could turn out over 60 dB EMI SE for foam and textiles. − For example, Zong et al reported that MXene-derived titanium carbon nanotubes (CNT) and cellulose-derived carbon aerogels were prepared by grafting, freeze-drying, and pyrolysing, which achieves an efficient EMI shielding effect of 72.9 dB …”

Cross-Linked and Rigid Polyimide Composite Foams with Prominent Fire Resistant, Thermal Insulating, and Wave-Transparent Properties

“…The obtained PI foams usually consist of aromatic structures which render the foams with advanced high temperature resistance, flame retardancy, and radiation resistance properties. Numerous efforts have focused on improving the mechanical properties of PI foams by modifying their molecular structures. , Li et al , introduced a rigid 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) monomer with higher rigidity into the PI molecular chains. With increasing BIA content, smaller and closed cells were obtained, and the density of the prepared PI foam could be controlled in the range of 20–100 kg·m –3 .…”