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Upcoming advancements in flexible technology require mechanically compliant dielectric materials. Current dielectrics have either high dielectric constant, K (e.g., metal oxides) or good flexibility (e.g., polymers). Here, we achieve a golden mean of these properties and obtain a lightweight, viscoelastic, high-K dielectric material by combining two nonpolar, brittle constituents, namely, sulfur (S) and selenium (Se). This S-Se alloy retains polymer-like mechanical flexibility along with a dielectric strength (40 kV/mm) and a high dielectric constant (K = 74 at 1 MHz) similar to those of established metal oxides. Our theoretical model suggests that the principal reason is the strong dipole moment generated due to the unique structural orientation between S and Se atoms. The S-Se alloys can bridge the chasm between mechanically soft and high-K dielectric materials toward several flexible device applications.

Until now, materials with high elasticity at deep cryogenic temperatures have not been observed. Previous reports indicated that graphene and carbon nanotube-based porous materials can exhibit reversible mechano-elastic behavior from liquid nitrogen temperature up to nearly a thousand degrees Celsius. Here, we report wide temperature-invariant large-strain super-elastic behavior in three-dimensionally cross-linked graphene materials that persists even to a liquid helium temperature of 4 K, a property not previously observed for any other material. To understand the mechanical properties of these graphene materials, we show by in situ experiments and modeling results that these remarkable properties are the synergetic results of the unique architecture and intrinsic elastic/flexibility properties of individual graphene sheets and the covalent junctions between the sheets that persist even at harsh temperatures. These results suggest possible applications for such materials at extremely low temperature environments such as those in outer space.

Two-dimensional (2D) chromium telluride Cr2Te3 exhibits strong ferromagnetic ordering with high coercivity at low temperatures and paramagnetic behavior when approaching room temperature. The spin states of monolayer Cr2Te3 show ferromagnetic ordering in the ground state. In situ Raman analysis reveals a reversible structure transformation and hence proves ferromagnetic to paramagnetic transition during low-temperature heating cycles (0–25 °C). The magnetic phase transition near room temperature in 2D Cr2Te3 prompted an exploratory study of these layered materials for energy application. We demonstrate that the low-temperature ferromagnetic behavior can be used to magnetically deice material surfaces using an external magnetic source, avoiding the use of harsh chemicals and high temperatures. The hydrophobic nature and dipole interactions of H2O molecules with the surface of the 2D Cr2Te3 coating aid in the condensation of ice droplets formed on the surfaces. First-principles calculations also confirm the observed crystal structure, surface interaction, and magnetic properties of 2D Cr2Te3. [ABSTRACT FROM AUTHOR]

Silica‐rich Green Graphene® (GG) derived from agricultural residue is incorporated into a floor epoxy (FEP) matrix. The inclusion of GG particles within the FEP matrix has demonstrated a significant positive impact, resulting in improved optical and mechanical properties and increased durability of the floor coatings. The addition of GG into the original FEP reduces surface pores, with the glazier appearance of the composite coating attributed to a smooth surface enhancing light reflection. It is noteworthy that the FEP exhibits a high coefficient of friction (CoF), thereby constraining its potential in tribo‐logical applications. Nano‐indentation and tribo‐logical tests confirm that, incorporation of the 0.5 wt% GG in the FEP matrix results in a 130.15% improvement in hardness, a 10.45% decrease of nano‐scratch depth, a 34.55% decrease in wear rate, and a 33.33% decrease in CoF w.r.t pristine FEP sample. Tensile testing reveals a significant 37% enhancement in fracture strain, along with improvements of 12.3% in specific flexural strength and 43% in energy absorption. The utilization of GG derived from green processes, such as pyrolysis of residual agro‐biomass, presents an environmentally conscious alternative to conventional polluting as well as nonrenewable materials employed in epoxy‐based floor coatings. Highlights: Green graphene/floor epoxy (GG/FEP) composites present a glazier appearance attributed to a smooth surface enhancing light reflection.GG particles enhance the hardness and tribo‐logical performance of the composite.GG/FEP composites show a synergistic enhancement in flexural strength.GG presents a sustainable and economically viable material for the epoxy‐based flooring industry. [ABSTRACT FROM AUTHOR]

Here metal support interaction (MSI) is demonstrated in a high entropy alloy (HEA: CoCuFeMnNi) supported CeO2. The HEA behaves as an active dry reforming catalyst only when it is supported over CeO2 oxide, clearly demonstrating MSI. Based on spectroscopic and microscopic observations, it is envisaged that the substitutional effect is the one that causes the lattice oxygen activation, an important active species during DRM reaction. Transient studies are performed to understand the surface chemistry of the interaction between methane and CO2 in the presence of a catalyst, which results in a methane decomposition first to generate hydrogen and carbon and followed by a CO2 reaction to give CO using deposited carbon. The experimental observations are further proven by mechanistic study with DFT calculations which show a major contribution of H‐assisted CO2 dissociation and pre‐H2 releasing carbon depositing CH4 dissociation and a minor contribution of pre‐CO releasing H2 formation. This MSI moves the d‐band center of the Co atoms of CoCuFeMnNi/CeO2 to the closest position of the Fermi level as compared to the isolated nanoparticles. This study can be taken as a proof of concept to demonstrate that MSI can be generated in the HEA/CeO2 catalysts for a generic heterogeneous gas phase reaction. [ABSTRACT FROM AUTHOR]

Photo-induced non-radiative energy dissipation is a potential pathway to induce structural-phase transitions in two-dimensional materials. For advancing this field, a quantitative understanding of real-time atomic motion and lattice temperature is required. However, this understanding has been incomplete due to a lack of suitable experimental techniques. Here, we use ultrafast electron diffraction to directly probe the subpicosecond conversion of photoenergy to lattice vibrations in a model bilayered semiconductor, molybdenum diselenide. We find that when creating a high charge carrier density, the energy is efficiently transferred to the lattice within one picosecond. First-principles nonadiabatic quantum molecular dynamics simulations reproduce the observed ultrafast increase in lattice temperature and the corresponding conversion of photoenergy to lattice vibrations. Nonadiabatic quantum simulations further suggest that a softening of vibrational modes in the excited state is involved in efficient and rapid energy transfer between the electronic system and the lattice.

This study comprehensively investigates for the first time the photocatalytic potential of a magnetic high entropy oxide (HEO), i.e., (FeCoNiCuZn)aOb, and unravels the fundamental mechanisms governing its exceptional performance over conventional semiconductor photocatalysts in degrading two common antibiotic pollutants, viz., sulfamethoxazole (SMX) and ofloxacin (OFX), in their aqueous phase. Synthesized via a facile, robust, and straightforward approach, the (FeCoNiCuZn)aOb nanoparticles (NPs) exhibit a remarkable photocatalytic degradation efficiency of 97% and 95% for SMX and OFX, respectively, upon exposure to visible light for 90 min. This outstanding activity can be primarily attributed to the coexistence of a vast number of distinct multielement active sites and numerous surface oxygen defects, intense and broadband absorption in the visible spectral region, and enhanced charge separation and transfer, as verified through optical, electrochemical, and photophysical analyses. Additionally, investigation into the contribution of active oxygen species reveals the predominant role of superoxide anions in the degradation and mineralization of antibiotics. In order to showcase the versatility of (FeCoNiCuZn)aOb NPs in water and wastewater treatment, the simultaneous dissociation of SMX and OFX is directly tested in six different real water matrixes, with the mean degradation efficiency decreasing in the sequence: groundwater (89%) > tap water (81%) > surface water (78%) > municipal wastewater (71%) > hospital wastewater (66%) > pharmaceutical wastewater (55%). Further, the HEO NPs can be readily separated from the reaction mixture via magnetic decantation, and reused multiple times without significant loss in stability or activity. These findings highlight the enormous potential of (FeCoNiCuZn)aOb NPs as next-generation photocatalysts for the removal of antibiotic residues from urban water systems. [ABSTRACT FROM AUTHOR]

Non-noble nanomaterial-based quasicrystals (QC) are attractive structures due to their potential surface plasmon resonance (SPR) properties and ability to be easily exfoliated into two-dimensional (2D) sheets. Interaction with and sensing of organic molecules are applications where such 2D materials are a viable option due to their large surface area to volume ratio, providing abundant active sites for molecular interactions. In this work, a titanium-based multicomponent alloy (Ti45Zr38Ni17) was exfoliated into a 2D quasicrystal (2D-Ti QC) from its bulk form via liquid-phase exfoliation. Structural and optical experimental techniques were used to characterize the 2D-Ti QC. Its plasmonic nature was verified and demonstrated via the absorbance spectrum, light localization images, and far-field diffraction patterns. Dopamine sensing was demonstrated using the absorbance spectra of optically active 2D-Ti QC. The linear range of detection was obtained as ∼13–91 nM (200–1400 ppb). Molecular dynamics (MD) simulations of Ti QC were conducted to investigate its structural stability. The interaction between 2D-Ti QC and dopamine was investigated by using DFT simulations. In this way, the potential of 2D-Ti QC to be used as an organic molecule sensor has been experimentally and theoretically demonstrated. [ABSTRACT FROM AUTHOR]