No abstract

An ultralight Ni-MOF-rGO aerogel which possess the merits of not only broad bandwidth and strong absorption but also lightweight and thin matching thickness is fabricated through a hydrothermal treatment, freeze-drying, and annealing procedure. The Ni@C microspheres are dispersed randomly and evenly on the graphene oxide (GO) nanosheets, which can be proved through SEM and TEM results. The electromagnetic parameters of the composite can be adjusted by changing the mass ratio of the MOF and GO to endow the material with both good impedance matching and superior electromagnetic wave absorption performances. Consequently, the resulting composite shows outstanding microwave absorption performance, which achieves strong absorption (−51.19 dB) and broad effective absorption bandwidth (6.32 GHz) with a thickness of 1.9 mm while the filling content is only 2 wt %. In addition, the multiple loss mechanisms of the Ni-MOF-rGO aerogel are illustrated, including conduction loss, dipolar polarization, interfacial polarization, magnetic resonance, and eddy current loss. In a word, the extraordinary microwave absorption performance is ascribed to the synergistic effects of the unique multiple layered structure of GO and the hollow core−shell structure of the Ni@C microsphere. This work demonstrates that the ultralight aerogel with excellent electromagnetic wave absorption performance is a promising strategy for microwave absorption application.

No abstract

Abstract— A novel reflective display based on electrowetting technology has gained much attention because of its readability in sun light. This technology can provide high‐efficiency control of the display pixel reflectivity. In the on‐state, the oil droplet is expected to move to the same corner regularly. To realize uniform motion of the oil, it is possible to provide a symmetry‐breaking mechanism in the pixel. However, depending on the uniformity of the processing and the size of the built‐in symmetry breaking, it is possible that the oil actually moves to a different position. The visibility of defects, by the representation of oil‐motion non‐uniformity, depending on different notch pattern, notch size, and defect type, has been investigated in the perception experiments. Results indicate that the influence of the defects is more obvious for the more preferred pattern. The larger the notch sizes, the easier the defects can be observed. The best notch pattern is pointed out. When designing an electrowetting display, these results need to be considered to eliminate the influence of oil‐motion non‐uniformity on the image quality by making the droplet as small as possible or by adding optical layers such as diffusers films.

Recently, the development of composite materials composed of magnetic materials and MXene has attracted significant attention. However, the thickness and microwave absorption performance of the composite is still barely satisfactory. In this work, the C-N@NiFe2O4@MXene/Ni nanocomposites were successfully synthesized in situ by hydrothermal and calcination methods. Benefiting from the introduction of the carbon-nitrogen(C-N) network structure, the overall dielectric properties are improved effectively, consequently reducing the thickness of the composite while maintaining excellent absorption performance. As a result, the minimum reflection loss of C-N@NiFe2O4@MXene/Ni can reach −50.51 dB at 17.3 GHz at an ultralow thickness of 1.5 mm, with an effective absorption bandwidth of 4.95 GHz (13.02–18 GHz). This research provides a novel strategy for materials to maintain good absorption performance at an ultralow thickness level.