Visualizing Nanoscale Interlayer Magnetic Interactions and Unconventional Low-Frequency Behaviors in Ferromagnetic Multishelled Structures.

Precise manipulation of van der Waals forces within 2D atomic layers allows for exact control over electron-phonon coupling, leading to the exceptional quantum properties. However, applying this technique to diverse structures such as 3D materials is challenging. Therefore, investigating new hierarchical structures and different interlayer forces is crucial for overcoming these limitations and discovering novel physical properties. In this work, a multishelled ferromagnetic material with controllable shell numbers is developed. By strategically regulating the magnetic interactions between these shells, the magnetic properties of each shell are fine-tuned. This approach reveals distinctive magnetic characteristics including regulated magnetic domain configurations and enhanced effective fields. The nanoscale magnetic interactions between the shells are observed and analyzed, which shed light on the modified magnetic properties of each shell, enhancing the understanding and control of ferromagnetic materials. The distinctive magnetic interaction significantly boosts electromagnetic absorption at low-frequency frequencies used by fifth-generation wireless devices, outperforming ferromagnetic materials without multilayer structures by several folds. The application of magnetic interactions in materials science reveals thrilling prospects for technological and electronic innovation.

The activation of oxygen through oxygen vacancies in BiOCl/PPy to inhibit toxic intermediates and enhance the activity of photocatalytic nitric oxide removal.

Photocatalysis is regarded as a promising technology for indoor air purification. Despite much effort, the inhibition of toxic intermediates and the promotion of nitric oxide (NO) oxidation activity still limit real applications due to catalyst design constraints. In order to circumvent this issue, oxygen vacancies were fabricated through a strong interaction between BiOCl and polypyrrole (PPy) based on computational predictions. Oxygen vacancies worked as sites to activate O2 molecules, and the relative barrier energies of NO oxidation were significantly reduced due to the O2 activation process. With the oxygen vacancy modification, the oxidizability of BiOCl was improved, and the generation of the superoxide radical (˙O2-) was promoted on BiOCl/PPy, while the hydroxyl radical (˙OH) remained unchanged under visible light irradiation. As a result, the efficiency of NO oxidation increased from 12% to 28%, while the NO2 production was inhibited completely. Finally, in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) investigations were conducted to shed light on the mechanism of the NO oxidation process. This work provides an in-depth understanding of the interaction between oxygen vacancies and O2 during the NO oxidation process, which offers a scheme to control the oxidation reaction.