Simultaneous Manipulation of Interfacial and Defects Polarization toward Zn/Co Phase and Ion Hybrids for Electromagnetic Wave Absorption

Abstract

Rational manipulation of multimetal hybrid materials (HMs) with tunable substitution or phases is evolving as an effective strategy to meet the controllable electromagnetic (EM) properties and EM wave (EMW) absorption. Herein, a new thermodynamic and kinetic cocontrol strategy is proposed to construct Zn/Co bimetal HMs with tuning ion and phase hybridization for synergistic effect on EM properties for the first time. Auxiliary chelating agent triethanolamine (TEA) dominates the phase separation by stepwise Zn/Co deposition in metal-organic frameworks, then the pyrolysis process under gradient temperature give rise to controllable ion hybridization products due to thermal motion. Benefiting from the tunable collaboration between defects polarization and interfacial polarization, the 700 °C HMs exhibit ultrahigh EM parameters and EMW absorption, of which products with no TEA deliver the effective absorbing bandwidth of 4.80 GHz (1.6 mm) and minimum reflection loss of −45.85 dB. The results indicated that synergistic effect of ion and phase hybridization can improve the defects induced "polarization centers" and coherent interfaces induced interfacial polarization. Furthermore, the comprehensive research and deep understanding on respective contribution of hybridization forms provide a precise inspiration in developing bimetal and even multimetal ferrite with tunable hybridization structure.

Enhancing the Low/Middle‐Frequency Electromagnetic Wave Absorption of Metal Sulfides through F− Regulation Engineering

“…As shown in Figure 6f, these defects would disrupt the lattice period and trigger abundant defect-induced dipoles, which acted as "polarization centers" to enhance defect-induced polarization and the relevant Debye relaxation process under the external EM field. [27,36] Furthermore, as shown in Figure 6g, because of the coexistence of acanthosphere-like structures, ample heterojunction interfaces, enriched defect levels, and strong electronic interactions (Figure 6d), F-12 exhibited improved electronic conductivity relative to F-0 and F-2 (Figure 6c), which was advantageous for the improved conduction loss. Thus, compared with others, the enhanced F − -regulated dielectric loss consisted of interfacial polarization, defect-induced polarization, and conduction loss, which accounted for the excellent EWM absorption capacity of F-12.…”

Dielectric Loss Mechanism in Electromagnetic Wave Absorbing Materials

“…Reproduced with permission. [176] Copyright 2021, Wiley-VCH. f) Simulated density of states (DOS) of H-MoO 3 with different content of hydrogen in the lattice, g) RL value curves before and after hydrogenation of MoO 3 samples, h) MoO 3 semiconductor was used as a representative to illustrate the mechanism of proton hydrogenation, and the electron cloud distribution of Mo-O and Mo-O-H. Reproduced with permission.…”

“…Recently, a thermodynamic and kinetic control strategy is proposed to construct Zn/Co bimetal HMs with tuning ion and phase hybridization for synergistic effect on EM properties (Figure 11d ). [ 176 ] Kinetic control process is achieved by different combination ability of Zn and Co ions toward chelating agent triethanolamine (TEA) while thermodynamic control is realized through gradient temperature treatment. At a low calcination temperature of 600 ℃, interfacial polarization is the dominated loss mechanism due to the coexistence of hexagonal ZnO, cubic Co, and transition state hexagonal Co when TEA content increment from 0 to 8 mmol.…”

Size-Dependent Oxidation-Induced Phase Engineering for MOFs Derivatives Via Spatial Confinement Strategy Toward Enhanced Microwave Absorption

“…2 j, the lattice spacing of 0.205 nm corresponds to the (111) plane of Co crystal and the spacing of 0.245 nm is assigned to the (311) plane of Co 3 O 4 , respectively. The clear grain boundaries with phase inversion, as indicated by blue area, imply that Co and Co 3 O 4 are separated with each other, verifying the phase conversion and generating phase hybridization with obvious coherent interfaces [ 34 ]. Simultaneously, a large number of defects can be observed (red circles), and both of the coherent interfaces and defects will trigger strong dipolar/interfacial polarization.…”