Oxygen Vacancy‐Induced Dielectric Polarization Prevails in the Electromagnetic Wave‐Absorbing Mechanism for Mn‐Based MOFs‐Derived Composites

Abstract

Polymeric metal-organic framework (MOF)-derived composites are promising functional materials because of their exceptional chemical homogeneity, designable components, and adjustable pore size. The modulation of oxygen and Mn vacancies via the introduction of heteroatoms and changes in the annealing temperature in MOFs-derived composites can be a possible solution to investigate the polarization loss mechanism, which facilitates the improvement of electromagnetic loss capacity. Herein, the design of laminate-stacked sphere-shaped trimetallic CoNiMn-MOFs is presented. The derived CoNi/ MnO@C composites retain the original topography of the MOFs. The concentration of oxygen vacancies increases with the incorporation of heteroatoms, but decreases with annealing temperature, which prevails in the polarization loss mechanism rather than the contribution of Mn 2+ vacancies and heterogeneous interfaces. Therefore, the minimum reflection loss of the CoNi/MnO@C sample demonstrates −55.2 dB at 2.6 mm and the broad effective absorption bandwidth reaches 8.0 GHz at 2.1 mm. This work is expected to provide meaningful insights into the significant effect of ion vacancy modulation on the EM wave-absorbing performance of Mn-based MOFs-derived composites.

Ambient-pressure ozone treatment enables tuning of oxygen vacancy concentration in the La1−xSrxFeO3−δ (0 ≤ x ≤ 1) perovskite oxides

“…[12][13][14] The oxygen vacancies can also affect other applications of oxides and their hybrids, such as electromagnetic wave absorption. [15][16][17][18] However, a versatile strategy of controlling the oxygen vacancy in metal oxides remains lacking. Hence, this work focuses on method development of tuning the oxygen vacancy density of metal oxides, in particular perovskite oxides such as La 1Àx Sr x FeO 3Àd (0 r x r 1, 0 r d r 0.5x), which are known to have a wide range of non-stoichiometry.…”

Facile synthesis of ultralight S-doped Co3O4 microflowers@reduced graphene oxide aerogels with defect and interface engineering for broadband electromagnetic wave absorption

“…Thereinto, vulcanization of Co 3 O 4 becomes an effective method of increasing defects, such as oxygen vacancies, causing dipole polarization loss. 29 The study of the EMA properties of cobalt sulfides is mainly focused on Co 1− x S, 30 CoS, 31 CoS 2 , 32 and Co 9 S 8 . 33 To further improve dipole polarization, defect engineering can modulate electromagnetic parameters and improve the EMA performance.…”

Efficient Heat Shielding and Ultraviolet Isolating Transparent Wood via In Situ Generation of TiO2 Nanoparticles

“…Among them, glass is widely used in architectural windows due to its low coefficient of thermal expansion (7−10 ppm K −1 ) and good transparency. 4,5 To meet the needs of impact resistance and sound insulation in daily life, the weight of glass continues to increase as it progresses from a single layer to multi-layer, which increases the safety hazard during transportation. Besides, concrete is the central part of the building material for supporting loads and resisting various forces (walls and roofs).…”

“…The development of the world economy is accompanied by energy consumption, of which residential consumption accounts for 30–40% of global consumption, and this proportion is still increasing. − As is known, the residential materials mainly include glass, concrete, and wood. Among them, glass is widely used in architectural windows due to its low coefficient of thermal expansion (7–10 ppm K –1 ) and good transparency. , To meet the needs of impact resistance and sound insulation in daily life, the weight of glass continues to increase as it progresses from a single layer to multi-layer, which increases the safety hazard during transportation. Besides, concrete is the central part of the building material for supporting loads and resisting various forces (walls and roofs).…”