Identification of the Intrinsic Dielectric Properties of Metal Single Atoms for Electromagnetic Wave Absorption

Abstract

Atomically dispersed metals on N-doped carbon supports (M–NxCs) have great potential applications in various fields. However, a precise understanding of the definitive relationship between the configuration of metal single atoms and the dielectric loss properties of M–NxCs at the atomic-level is still lacking. Herein, we report a general approach to synthesize a series of three-dimensional (3D) honeycomb-like M–NxC (M = Mn, Fe, Co, Cu, or Ni) containing metal single atoms. Experimental results indicate that 3D M–NxCs exhibit a greatly enhanced dielectric loss compared with that of the NC matrix. Theoretical calculations demonstrate that the density of states of the d orbitals near the Fermi level is significantly increased and additional electrical dipoles are induced due to the destruction of the symmetry of the local microstructure, which enhances conductive loss and dipolar polarization loss of 3D M–NxCs, respectively. Consequently, these 3D M–NxCs exhibit excellent electromagnetic wave absorption properties, outperforming the most commonly reported absorbers. This study systematically explains the mechanism of dielectric loss at the atomic level for the first time and is of significance to the rational design of high-efficiency electromagnetic wave absorbing materials containing metal single atoms.

An Equivalent Substitute Strategy for Constructing 3D Ordered Porous Carbon Foams and Their Electromagnetic Attenuation Mechanism

“…Furthermore, the pyridine-type nitrogen atom that was embedded in the carbon lattice structure can improve the conductivity of EDCF, which is easy to migrate and transmit electrons and dissipates the energy of electromagnetic waves through polarization relaxation. Many defects and functional groups containing N, O, and P atoms result in localized states of Fermi level, which is also conducive to the absorption and attenuation of electromagnetic waves [ 74 ]. In the solid-air interface, a large amount of charge in the external electromagnetic field is accumulated, resulting in strong space charge polarization, which plays a positive role in attenuating EMW energy [ 75 ].…”

Sub‐Nanometer Fe Clusters Confined in Carbon Nanocages for Boosting Dielectric Polarization and Broadband Electromagnetic Wave Absorption

“…demonstrated that the synergistic effects constructed in N‐doped core‐shell heterojunctions can enhance the EM wave absorption properties at gigahertz. [ 23 ] Moreover, the hetero‐substituted microwave absorbers with 3D structures could thus establish an interconnected network and promote improved dielectric loss capacities, [ 24 ] such as the honeycomb‐like M–N x C, [ 25 ] hollow N‐doped carbon nanoplates, [ 26 ] and N‐doped graphene aerogels. [ 27 ]…”

“…Electromagnetic (EM) wave absorption materials have attracted considerable attention because of widely applications of electronic devices and communications facilities. [1][2][3][4][5] The EM wave absorption performances are strictly related to the complex permittivity (ε r ) and permeability (μ r ) and their impedance matching, which are mainly associated with dielectric loss capacities, [24] such as the honeycomb-like M-N x C, [25] hollow N-doped carbon nanoplates, [26] and N-doped graphene aerogels. [27] In this study, we achieved various hetero-substitutions in the nitrogen-substituted carbon nanocages (NCNs), including single Fe atoms, subnanometer Fe clusters, and Fe 3 O 4 nanoparticles, by carbonizing the metal-organic frameworks composites under proper temperatures.…”

Wrinkled Titanium Carbide (MXene) with Surface Charge Polarizations through Chemical Etching for Superior Electromagnetic Interference Shielding

“…[24] Interestingly, un-artificial wrinkles within 2D MXene nano-sheets, which are introduced inevitably during the acid etching due to defect-or dislocation-induced stress, have a strong influence on their chemical and electrical properties. [25] Enhanced absorption has been realized in carbon-based materials with the doping of metal single-atoms, [26,27] where the electric dipole can play a key role. [28] Therefore, the effective engineering of wrinkles in MXenes offers new possibilities to construct high-performance EMI shielding films with electric-dipole-induced EW absorption.…”