We demonstrate a dual-band, polarization-insensitive, ultrathin and flexible metamaterial absorber (MA), based on high-order magnetic resonance. By exploiting a flexible polyimide substrate, the thickness of MA came to be 1/148 of the working wavelength. The absorption performance of the proposed structure was investigated for both planar and bending models. In the case of the planar model, a single peak was achieved at a frequency of 4.3 GHz, with an absorption of 98%. Furthermore, additional high-order absorption peaks were obtained by the bending structure on a cylindrical surface, while the fundamental peak with a high absorption was maintained well. Our work might be useful for the realization and the development of future devices, such as emitters, detectors, sensors, and energy converters.
The optical properties of MoS2 and WS2 monolayers are significantly influenced by fabrication methods, especially with respect to the behavior of excitons at the K−point of the Brillouin zone. Using spectroscopic ellipsometry, we obtain the complex dielectric functions of monolayers of these materials from cryogenic to room temperatures over the energy range 1.5 to 6.0 eV. The excitonic structure of each sample is analyzed meticulously by fitting the data to a standard analytical function to extract the energy positions of the excitons at each temperature. At low temperatures, excitonic structures are blue-shifted and sharpened due to the reduction in phonon noise and lattice distance. The excitons of monolayers fabricated by MOCVD separate into sub-structures at low temperatures, while monolayers grown by LPCVD and APCVD remain a single peak. The origin of these peaks as charged or neutral excitons follows from their temperature dependences.
We report the complex dielectric function ε = ε1 + iε2 of MoS2/WS2 and WS2/MoS2 heterostructures and their constituent monolayers MoS2 and WS2 for an energy range from 1.5 to 6.0 eV and temperatures from 39 to 300 K. Comparisons between the optical properties of the heterostructures and their monolayers were conducted. Critical-point (CP) energies of the heterostructures were traced back to their origins in the monolayers. Low-temperature measurements confirmed the existence of only three excitonic CPs from 1.5 to 2.5 eV due to the overlap of trion B− of the MoS2 monolayer and exciton A0 of the WS2 monolayer. Due to the dielectric screening effect, most CPs exhibit red shifts in the heterostructures compared to their monolayer counterparts.
Polydopamine (PDA) is an emerging biomimetic material that stimulates the distinctive physicochemical properties of the blue mussel byssus. In this study, we report a rapid and facile method for the decoration of gold nanoparticles (AuNPs) onto the mussel-inspired polydopamine nanospheres (PDA NSs) via cold atmospheric plasma treatment. After 10 min of plasma treatment, AuNPs with a size of 10.3 ± 2.0 nm were formed on the surface of PDA NSs. This reaction was performed without the need for any additional reducing agents, thereby eliminating the use of harsh chemicals during the process. The synthesized AuNP-decorated PDA nanohybrids (PDA-Au) exhibit effective catalytic activity for the decoloration of Rhodamine B, with a pseudo-first-order rate constant of 1.405 min−1. The green synthesis approach in this work highlights the potential of plasma-assisted methods for decorating biomimetic materials with metallic nanoparticles for catalytic and environmental applications.
Plasma–liquid interactions (PLIs) have emerged as a rapid and reagent-minimized platform for the synthesis of gold nanomaterials (GNMs) with tunable size, morphology, crystallinity, and surface chemistry. In contrast to conventional wet-chemical routes, non-thermal atmospheric-pressure plasmas reduce HAuCl4 through highly reactive species generated at the gas–liquid interface. This review consolidates the field by classifying PLIs systems into four categories based on the discharge configuration, including plasma electrochemistry, plasma jet, solution plasma, and plasma aerosol, and critically compares their mechanisms and operational parameters. We show that the relative weighting of key process variables is strongly configuration-specific, with short-lived species initiating burst nucleation and long-lived neutrals sustaining autocatalytic growth. Furthermore, the review highlights how the distinct characteristics of each PLI configuration affect nanoparticle formation, morphology evolution, and physicochemical properties, providing practical guidance for selecting appropriate plasma systems for the controlled synthesis of gold nanomaterials.
In this study, SiOx/spherical graphite (SiOx/SG) composites were successfully prepared as high-performance anode materials for lithium-ion batteries through the combination of thermal plasma and ball milling approach. The thermal plasma method enabled the production of SiOx nanoparticles with controlled morphology and particle size, ensuring high purity and homogeneity. These nanoparticles were then uniformly dispersed into spherical graphite (SG) via ball milling, forming a composite with enhanced structural stability and electrochemical performance. The resulting SiOx/SG composite exhibited superior electrochemical properties, including high specific capacity, excellent cycling stability, and improved rate capability. This synergistic approach offers an efficient, scalable, and industrially viable route for developing advanced anode materials for next-generation lithium-ion batteries.