Balancing Between Polarization and Conduction Loss toward Strong Electromagnetic Wave Absorption of Hard Carbon Particles with Morphology Heterogeneity.

The heterostructure and hierarchical morphology of carbonaceous absorbents play an important role in the construction of high-performance electromagnetic wave absorbing materials. Herein, novel micron-scale hard carbon particles with morphology heterogeneity were developed as lightweight superior electromagnetic wave absorbents via a facile and ecofriendly process. The as-prepared hard carbon particle composed of pseudographite and a highly disordered region shows a unique heterostructure. Concurrently, constructing a multilevel geometric shape and size can cause a decrease of the percolation threshold and an excellent balance between polarization and conduction loss, which enhances the electromagnetic wave absorption significantly. The composites (thickness d = 2.36 mm) filled with morphology-heterogeneity hard carbon particles (15 wt %) achieve an excellent electromagnetic wave absorption with a minimum reflection loss of -78.0 dB at 10.2 GHz and effective absorption bandwidth (<-10 dB) of 3.1 GHz (8.8-11.9 GHz). Compared to the traditional carbonaceous absorbents with complex microstructures and/or multiple chemical components, this work presents a feasible idea for the development of an efficient carbonaceous absorbent to realize practical applications.

Flexible and Transparent Ferroferric Oxide-Modified Silver Nanowire Film for Efficient Electromagnetic Interference Shielding.

Transparent and flexible electromagnetic interference (EMI) shielding film is highly desirable due to the fast-growing flexible electronics. A silver nanowire (Ag NW) film is considered to be an ideal candidate for a transparent and flexible EMI shielding film but suffers low EMI shielding effectiveness (SE) at high transparency and poor bending durability. Herein, we introduce ferroferric oxide (Fe3O4) into a Ag NW film and demonstrate a robust EMI shielding film, which exhibits SE of 24.9 dB at 8.2 GHz and optical transparency of 90%. Fe3O4 exhibits roles of the improved absorption loss for electromagnetic radiation due to its high permeability, the enhanced reflection loss for electromagnetic radiation by increasing the conductivity of Ag NWs film, and the improved stability for the enhanced adhesion of the Ag NW EMI shielding film. Our work provides a facile method for high-performance transparent EMI shielding film, which exhibits great potential for protection for electronic devices.