Exploring the Ni 3d Orbital Unpaired Electrons Induced Polarization Loss Based on Ni Single‐Atoms Model Absorber

Abstract

Single-atoms (SAs) strategies have been proved to be effective in modulating electromagnetic wave (EMW) absorption, however, the establishment of a definitive relationship between metal SAs electronic configurations and physical loss mechanisms has been still absent, especially on the atomic scale. Herein, stable Ni-SAsx/N-doped carbon (NC) absorbers are fabricated with the strategy of ligand polymerization. The morphology, composition, electrical conductivity, defects, and electronic interactions of the material can be well tailored by Ni species modulation engineering. Theoretical and experimental results show that the atomically dispersed individual Ni atoms contribute to enhanced EMW absorption performance through excess Ni 3d orbital unpaired electron induced polarization loss. Benefiting from it, Ni-SAs3/NC with the highest Ni SAy-Nx (y > 1, x > 1) polar/defect centers exhibit excellent EMW absorption with an effective absorption bandwidth of 7.08 GHz at a matched thickness of 2.50 mm. Radar cross-section simulations further demonstrate its potential for practical application as EMW absorber. This study reveals the continuous evolution of microscopic electromagnetic loss mechanism (i.e., conduction loss→ unique polarization loss→ conduction loss) for the first time, which provides insight into the deep design of absorbers from atom-scale view.

Surface engineering of nanoflower-like MoS2 decorated porous Si3N4 ceramics for electromagnetic wave absorption

“…In all samples, the peaks of N–Si bonds were shifted toward higher binding energies (Fig. S4d†), indicating electron transfer from Si 3 N 4 to MoS 2 , 39,47 which further demonstrated strong interactions between Si 3 N 4 and MoS 2 . Fig.…”

“…These defects can break the lattice period and tune electric eld and electric transport paths, thus impeding the movement of free electrons and generating charge aggregation. 39,40 The uneven distribution of the charge around the defects produced a large number of dipoles. The dipoles rotated repeatedly under the alternating electromagnetic eld, thus generating polarization relaxation for EMW dissipation.…”

“…8c were attributed to resonance within the material. 39 Fig. 9 compares the EMW absorption performance of MoS 2 / Si 3 N 4 ceramics prepared in this work with contemporary ceramic materials.…”

Regulated electron migration in sandwich-like m-Ti3C2/Fe3O4 composites derived from electrostatic assembly boosted electromagnetic wave absorption

“…41,42 High 3 ′′ denotes a desirable ability to dissipate EM energy but is hardly conducive to impedance matching, which results in the total reection of the EM wave. [43][44][45][46] Pure Fe 3 O 4 nanoparticles exhibit utterly low 3 ′′ on the contrast (Fig. S3a †), revealing their negligible dielectric loss capacity.…”

“…In order to get insights into the evolution of EM wave absorption performance, impedance matching calculations are carried out. According to transmission line theory, impedance matching can be calculated using the following equation: 44,62…”