Nanotechnology最新文献

Cocatalysts generally serve as active sites accelerating carrier separation. However, when the hydrophilicity of photocatalyst itself is poor, the trapped electrons or holes on cocatalysts are difficult to react with reactants quickly. In this work, Bi₄Ti₃O₁₂nanosheets with excellent hydrophilicity was prepared and then thermally deposited Rh on their surface (Bi₄Ti₃O₁₂(Rh)), and finally in-suit grew ZnIn₂S₄on the surface of Bi₄Ti₃O₁₂(Rh). Based on the results of photocatalytic performance and materials characterization, it was found that the Bi₄Ti₃O₁₂(Rh) in the photocatalytic system could be considered as a special cocatalyst rather than formed heterojunction with the ZnIn₂S₄. Under visible-light irradiation, the Rh acted as an electron trapping site to conduct photogenerated electrons trapping from ZnIn₂S₄to the surface of Bi₄Ti₃O₁₂. This process not only further accelerated carrier separation, but also facilitated electrons reacting with water due to the excellent hydrophilicity of Bi₄Ti₃O₁₂(Rh), thereby achieving enhanced photocatalytic H₂production performance in the absence of sacrificial agents.

Due to the unique self-assembling structure and rheological properties, supramolecular gel lubricants have become the third major type of liquid lubricating materials to supplement the lubricating oils and greases. The molecular structures of gelators applicable to oil-based, water-based and extreme conditions base oils were summarized firstly. Furthermore, this review aims at exploring the relationships between the molecular structures of gelators and the gel-forming, rheological and tribological properties of gel lubricants. Based on the wide application of gel in various lubrication fields, the synergistic lubricating effect between gel lubricants and nanomaterials, films, textured surfaces were analyzed. The design of solid-liquid composite lubrication systems based on gel lubricants and solid lubricants were attempted to be highlighted and revealed. Finally, the perspectives on the development of gel lubricants and corresponding composite lubricating materials were presented.

Gate-all-around (GAA) nanosheet field-effect transistors (FETs) have significantly advanced nanoscale device technology by mitigating short-channel effects. These GAA structures are becoming essential in sub-3 nm technology and are evolving into complementary FETs. Despite the reduction in variability achieved by multi-gate structures, random discrete dopants (RDDs) in source and drain (S/D) regions continue to pose challenges. This study addresses the local variability induced by RDDs, particularly in the S/D extensions in GAA nanosheet FETs. Through statistical quantum transport simulations under a ballistic approximation, we investigate parameters such as spacer length, channel width, and channel thickness. The results show that RDDs in the S/D extensions cause not only threshold voltage variation but also increase resistance and reduce ON-state current. GAA nanosheet FETs with a3 nm×10 nmcross-sectional channel and 5 nm spacer length exhibit 10% reduction in ON-state current compared to the ideal device, along with a standard deviation (variability) of 0.35µA. Mitigation of these effects requires the use of thin, wide, and large cross-section nanosheets and short spacer lengths.

Graphene Oxide (GO) is a two-dimensional (2D) nanomaterial largely exploited in many fields. Its preparation, usually performed from graphite in an oxidant environment, generally affords 2D layers with a broad size distribution, with overoxidation easily occurring. Here, we investigate the formation, along the Hummers synthesis of GO, of carbon nanoparticles (CNPs) isolated from GO and characterized through morphological and spectroscopic techniques. The purification methodology here applied is based on dialysis and results highly advantageous, since it does not involve chemical processes, which may lead to modifications in the composition of GO layers. Using a cross-matched characterization approach among different techniques, such as x-ray photoelectron spectroscopy, cyclic voltammetry and fluorescence spectroscopy, we demonstrate that the isolated CNP are constituted by layers that are highly oxidized at the edges and are stacked due toπ-πinteraction among their aromatic basal planes and H-bonded via their oxidized groups. These results, while representing a step forward in the comprehension of the structure of long-debated carbon debris in GO, strongly point to the introduction of dialysis as an indispensable step toward the preparation of more controlled and homogeneous GO layers and to its use for the valorization of low molecular weight GO species as luminescent CNPs.

In this work, Pd-TiO₂/ZnIn₂S₄nanowires (Pd-Ti-Nws/ZIS) heterostructures catalysts were prepared and applied to photocatalytic hydrogen evolution under simulated sunlight. The results revealed that the hydrogen production rate of Pd-Ti-Nws-40/ZIS was as high as 66.7 mmol·g^-1·h^-1, which was 20.5 and 418 times as much as that of pure ZIS and Pd-Ti-Nws, respectively. After 5 cycles, the hydrogen production of the photocatalyst can still reach about 60 mmol within 120 min. According to the results of photochemistry and x-ray photoelectron spectroscopy, Pd-Ti-Nws/ZIS meets the S-scheme heterojunction system, which is beneficial to inhibit the recombination of photogenerated holes and electrons and increase carrier transport rate through the S-scheme heterojunction. Under light radiation, Pd-Ti-Nws is positively charged due to the accumulation of holes, and ZIS is negatively charged due to the accumulation of electrons with higher reducing power. Moreover, Pd nanoparticles obviously improve the response range and intensity of the catalyst to sunlight. Therefore, the photocatalytic hydrogen production rate obviously increased. This work provides a reasonable method for designing efficient catalysts for photocatalytic hydrogen production.

This study presents a detailed investigation into the fluorescence properties of color centers in single-crystal diamond needles (SCDNs) synthesized via chemical vapor deposition. Using steady-state and time-resolved photoluminescence (PL) techniques, we identified color centers with zero-phonon lines at 389 nm, 468 nm, 575 nm (NV⁰), 637 nm (NV^-), and 738 nm (SiV^-). PL excitation spectroscopy conducted at room temperature revealed the complex electronic structure of some of these centers, paving the way for further investigation into their fluorescence properties. Lifetime measurements were performed for each center, with the 389 nm one exhibiting the longest decay time (∼30 ns), which is advantageous for enhancing quantum coherence, improving photon emission efficiency, and reducing power consumption. Altogether, these findings highlight the potential of SCDNs for quantum applications and confirm their promise as a platform for next-generation photonic and quantum devices.

The progression of quantum phenomena aligns closely with the miniaturization of nano-semiconductor transistors. This necessitates innovative quantum structures beyond traditional transistor types. Investigating electrostatically defined nanoscale devices within two-dimensional (2D) semiconductor heterostructures, particularly van der Waals heterostructures offers advantages like large-scale uniformity and flexibility. Here, we focus on the charge transport of a MoS₂/WSe₂encapsulated heterostructure controlled by a split-gate configuration, revealing a distinctive step-like current profile at a low temperature of 77 K. The observed distinguishable regimes in the current highlight the impact of quantum confinement induced by reduced lateral dimensions coupled with precise electrostatic confinement controlled by gate voltages. The temperature dependence of the device is also investigated to understand the role of thermal effects on the observed electrostatic-controlled transconductance oscillations phenomenon. This study contributes to a deeper understanding of electrostatic effects in 2D transition metal dichalcogenide heterostructures in narrow regimes. It holds promise for developing future integrated electronic devices based on 2D semiconducting nanomaterials with tailored confinement and enhanced functionalities.

Nanochains (NCs) made up of a one-dimensional arrangement of magnetic nanoparticles (NPs) exhibit anisotropic properties with potential for various applications. Herein, using a novel self-assembly method we directly integrate single NCs onto desired substrates including devices. We present a nanoscopic analysis of magnetization reversal in 1D linear NP arrays by combining x-ray microscopy, magnetoresistance (MR), and micromagnetic simulations. Imaging the local magnetization along individual NCs by scanning transmission x-ray microscopy and x-ray magnetic circular dichroism under varyingin situmagnetic fields shows that each structure undergoes distinct non-homogeneous magnetization reversal processes. The experimental observations are complemented by micromagnetic simulations, revealing that morphological inhomogeneities critically influence the reversal process where regions with parallel chains or larger multi-domain particles act as nucleation centers for the magnetization switching and smaller particles provide pinning sites for the domain propagation. Magnetotransport through single NCs reveals distinct MR behavior that is correlated with the unique magnetization reversal processes dictated by the morphology of the structures. This study provides new insights into the complex magnetization reversal mechanism inherent to one-dimensional particle assemblies and the effective parameters that govern the process.

A novel Hoffmann-type metal-organic framework ultra-wide bandgap semiconductor material, {Ni(DMA)₂[Ni(CN)₄]}(DMA denotes dimethylamine), has been predicted. The material has been named Ni-DMA-Ni, and its structure, stability, electronic, mechanical, optical, and transport properties have been investigated by first-principles simulations. The calculation results demonstrate that Ni-DMA-Ni exhibits excellent thermal and dynamics stability at room temperature, with a bandgap value as high as 4.89 eV and the light absorption capacity reaches 10⁵cm^-1level in the deep ultraviolet region. The Young's modulus is 27.94 GPa, and the shear modulus is 10.82 GPa, indicating mechanical anisotropy. In addition, the construction of a two-probe device utilizing Ni-DMA-Ni to evaluate its transport properties revealed a negative differential resistance effect in itsI-Vcharacteristic curve. These unique properties highlight the potential application of the Ni-DMA-Ni material in the deep ultraviolet optoelectronic field. This study provides novel concepts and contributes significant insights to the research of Hoffmann-type semiconductor materials in the field of optoelectronic devices.

To accurately achieve structure height differences in the range of single digit nanometres is of great importance for the fabrication of diffraction gratings for the extreme ultraviolet range (EUV). Here, structuring of silicon irradiated through a mask by a broad beam of helium ions with an energy of 30 keV was investigated as an alternative to conventional etching, which offers only limited controllability for shallow structures due to the higher rate of material removal. Utilising a broad ion beam allows for quick and cost effective fabrication. Ion fluence of the irradiations was varied in the range of 10¹⁶ ... 10¹⁷ ions · cm^-2. This enabled a fine tuning of structure height in the range of 1.00 ± 0.05 to 20 ± 1 nm, which is suitable for shallow gratings used in EUV applications. According to transmission electron microscopy investigations the observed structure shape is attributed to the formation of point defects and bubbles/cavities within the silicon. Diffraction capabilities of fabricated elements are experimentally shown at the SX700 beamline of BESSY II. Rigorous Maxwell solver simulation based on the finite-element method and rigorous coupled wave analysis are utilised to describe the experimental obtained diffraction pattern.