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

Abstract

Precisely reducing the size of metal-organic frameworks (MOFs) derivatives is an effective strategy to manipulate their phase engineering owing to size-dependent oxidation; however, the underlying relationship between the size of derivatives and phase engineering has not been clarified so far. Herein, a spatial confined growth strategy is proposed to encapsulate small-size MOFs derivatives into hollow carbon nanocages. It realizes that the hollow cavity shows a significant spatial confinement effect on the size of confined MOFs crystals and subsequently affects the dielectric polarization due to the phase hybridization with tunable coherent interfaces and heterojunctions owing to size-dependent oxidation motion, yielding to satisfied microwave attenuation with an optimal reflection loss of −50.6 dB and effective bandwidth of 6.6 GHz. Meanwhile, the effect of phase hybridization on dielectric polarization is deeply visualized, and the simulated calculation and electron holograms demonstrate that dielectric polarization is shown to be dominant dissipation mechanism in determining microwave absorption. This spatial confined growth strategy provides a versatile methodology for manipulating the size of MOFs derivatives and the understanding of size-dependent oxidation-induced phase hybridization offers a precise inspiration in optimizing dielectric polarization and microwave attenuation in theory.

Hydrogel-based composites beyond the porous architectures for electromagnetic interference shielding

“…Eventually, the Co/C@CNF aerogel reached an EMI SE of around 35.1 dB at a density of 1.74 mg•cm −3 , and the corresponding SSE was 20,172.4 dB•cm 3 •g −1 . Wang et al also reported the enhancement in EMI SE of CNF/MXene aerogels (CTA) with aligned porous structure [120]. After annealing, anisotropic morphology could be well preserved (Fig.…”

MXene-Reinforced Liquid Metal/Polymer Fibers via Interface Engineering for Wearable Multifunctional Textiles

“…Due to the high conductivity, the impedance mismatch at the interfaces between fiber and air leads to strong reflection of EM waves (Figure S24). Meanwhile, a large induced current is generated inside the fibers because of the high conductivity, which can significantly convert EM energy into thermal energy. , Besides, polarization relaxation loss and magnetic loss also contribute to the attenuation of EM waves inside the fibers. − Figure S25 presents the frequency dependence of the complex permittivity (ε r = ε′ – i ε″) and complex permeability (μ r = μ′ – i μ″) of the M 0.1 LM 5 S textile. The presence of resonant peak in the imaginary permittivity (ε″) curve and the Cole–Cole semicircles in ε″−ε′ curve demonstrate the generation of polarization relaxation loss (Figure S25a,b).…”

Ion‐Exchange Strategy for Metal‐Organic Frameworks‐Derived Composites with Tunable Hollow Porous and Microwave Absorption

“…Set the fully open boundary condition and selected the monitoring frequency of 14 GHz. The incident angle of the electromagnetic wave was adjusted (‐60°‐60°), and the value was calculated by S (the area of the simulation model), λ (electromagnetic wave wavelength), E s (the electric field intensity), and E i (the incident wave): [ 64 ] $$\[ \begin{array}{*{20}{c}}{RSC\left( {dB\,{m^2}} \right) = 10\log {{\left( {\left( {4\pi S/{\lambda ^2}} \right)|{E_S}/{E_{\rm{i}}}|} \right)}^2}}\end{array} \]$$…”

“…Set the fully open boundary condition and selected the monitoring frequency of 14 GHz. The incident angle of the electromagnetic wave was adjusted (−60°-60°), and the value was calculated by S (the area of the simulation model), λ (electromagnetic wave wavelength), E s (the electric field intensity), and E i (the incident wave): [64] RSC dBm S E E S π λ ( )…”