Naktal

Anisotropic 2D layered material rhenium disulfide (ReS₂) with high crystal quality and uniform monolayer thickness is synthesized by using tellurium-assisted epitaxial growth on mica substrate. Benefit from the lower eutectic temperature of rhenium-tellurium binary eutectic, ReS₂ can grow from rhenium (melting point at 3180 °C) and sulfur precursors in the temperature range of 460–900 °C with high efficiency.

A high-performance ReS₂-based thin-film transistor and photodetector with high on/off-current ratio (10⁴), high mobility (7.6 cm² V⁻¹ s⁻¹), high photoresponsivity (2.5 × 10⁷ A W⁻¹), and fast temporal response (rising and decaying time of 670 ms and 5.6 s, respectively) through O₂ plasma treatment is reported.

A 2D system of Er-doped MoS₂ layered nanosheets is developed. Structural studies indicate that the Er atoms can be substitutionally introduced into MoS₂ to form stable doping. Density functional theory calculation implies that the system remains stable. Both NIR-to-NIR up-conversion and down-conversion light-emissions are observed in 2D transition metal dichalcogenides, ascribed to the energy transition from Er³⁺ dopants.

MoS2 monolayers, a two-dimensional (2D) direct semiconductor material with an energy gap of 1.9 eV, offer many opportunities to be explored in different electronic devices. Defects often play dominant roles in the electronic and optical properties of semiconductor devices. However, little experimental information about intrinsic and extrinsic defects or impurities is available for this 2D system, and even for macroscopic 3D samples for which MoS2 shows an indirect bandgap of 1.3 eV. In this work, we evaluate the nature of impurities with unpaired spins using electron paramagnetic resonance (EPR) in different geological macroscopic samples. Regarding the fact that monolayers are mostly obtained from natural crystals, we expect that the majority of impurities found in macroscopic samples are also randomly present in MoS2 monolayers. By EPR at low temperatures, rhenium donors and sulfur vacancy acceptors are identified as the main impurities in bulk MoS2 with a corresponding donor concentration of about 10^8–12 defects/cm² for MoS2 monolayer. Electrical transport experiments as a function of temperature are in good agreement with the EPR results, revealing a shallow donor state with an ionization energy of 89 meV and a concentration of 7 × 10¹⁵cm⁻³, which we attribute to rhenium, as well as a second deeper donor state with ionization energy of 241 meV with high concentration of 2 × 10¹⁹cm⁻³ and net acceptor concentration of 5 × 10¹⁸cm⁻³ related to sulfur vacancies.

Superior chemical sensing performance of black phosphorus (BP) is demonstrated by comparison with MoS₂ and graphene. Dynamic sensing measurements of multichannel detection show that BP displays highly sensitive, selective, and fast-responsive NO₂ sensing performance compared to the other representative 2D sensing materials.

Through billions of years of evolution and natural selection, biological systems have developed strategies to achieve advantageous unification between structure and bulk properties. The discovery of these fascinating properties and phenomena has triggered increasing interest in identifying characteristics of biological materials, through modern characterization and modeling techniques. In an effort to produce better engineered materials, scientists and engineers have developed new methods and approaches to construct artificial advanced materials that resemble natural architecture and function. A brief review of typical naturally occurring materials is presented here, with a focus on chemical composition, nano-structure, and architecture. The critical mechanisms underlying their properties are summarized, with a particular emphasis on the role of material architecture. A review of recent progress on the nano/micro-manufacturing of bio-inspired hybrid materials is then presented in detail. In this case, the focus is on nacre and bone-inspired structural materials, petals and gecko foot-inspired adhesive films, lotus and mosquito eye inspired superhydrophobic materials, brittlestar and Morpho butterfly-inspired photonic structured coatings. Finally, some applications, current challenges and future directions with regard to manufacturing bio-inspired hybrid materials are provided.

Typical, naturally-occurring materials are reviewed, with a focus on chemical composition, nanostructure, and architecture. The critical mechanisms underlying their properties are summarized, with a particular emphasis on the role of material architecture. A review of recent progress on the nano/micro-manufacturing of bio-inspired hybrid materials is then presented in detail.