Engineering Phase to Reinforce Dielectric Polarization in Nickel Sulfide Heterostructure for Electromagnetic Wave Absorption

Abstract

Engineering phase transition in micro‐nanomaterials to optimize the dielectric properties and further enhance the electromagnetic microwave absorption (EMA) performance is highly desirable. However, the severe synthesis conditions restrict the design of EMA materials featuring controllable phases, which hinders the tunability of effective absorption bandwidth (EAB) and leads to an unclear loss mechanism. Herein, a seed phase decomposition‐controlled strategy is proposed to induct nickel sulfide (NiSx) absorbers with controllable phases and hollow sphere nature. Transmission electron microscopy holography and theoretical calculations evidence that the reconstruction of atoms in phase transition induces numerous heterogeneous interfaces and lattice defects/sulfur vacancies to cause varied work functions and local electronic redistribution, which contributes to reinforced dielectric polarization. As a result, the optimized NiS2/NiS heterostructure enables enhanced EM attenuation capability with a wide EAB of 5.04 GHz at only 1.6 mm, compared to that of NiS2 and NiS. Moreover, the correlation between EAB and NiS phase content is demonstrated as the “volcano” feature. This study on the concept of phase transition of micro‐nanomaterials can offer a novel approach to constructing highly efficient absorbers for EMA and other functionalities.

Nanozyme Catalytic Performance Enhancement through Defect and Electronic Structure Regulation of Metal-Doped NiCo2O4@Pd

“…Reconstruction of the hologram images (Figure a2–d2), the phase shift profiles can be further transformed into electrostatic potential according to the Poisson’s eq (Figure S12). , The corresponding conversion results of charge density curves were calculated in Figure a3–d3. The Fe-NiCo 2 O 4 @Pd exhibit intense electron redistribution at the interface of Fe-NiCo 2 O 4 and Pd.…”