Nanotechnology最新文献

Molybdenum disulfide (MoS₂) possesses excellent potential for applications in the field of optoelectronic detection. However, the atomic-level thickness of the monolayer MoS₂leads to weak light absorption and a restricted absorption spectrum. The performance of monolayer MoS₂devices has reached a bottleneck. Fortunately, the above issues can be effectively solved by coupling with various types of photosensitivity nanostructures. In this work, we integrated MoS₂quantum dots (QDs) with high efficient light absorption with monolayer MoS₂to fabricate 0D/2D MoS₂QDs/MoS₂hybrid dimensional homojunction photodetectors. In this structure, MoS₂is used as an efficient carrier transport channel, while MoS₂QDs act as effective light absorbers to enhance the local electric field around MoS₂. The synergistic effect of MoS₂QDs and MoS₂is utilized to accelerate the migration rate of photogenerated carriers in the structure, and in particular, the highest responsivity of the MoS₂QDs/MoS₂hybrid device is 27.6 A W^-1with the detectivity as high as 2.13 × 10¹¹Jones under 532 nm laser, which is an order of magnitude higher than that of the pristine MoS₂devices. The synergistic effect of MoS₂QDs with monolayer MoS₂is verified by finite-difference time-domain simulation. The results will pave the way for the future development of high-performance MoS₂-based photodetectors.

Nitrogen-doped carbon dots (N-CDs) and vertically-grown tin disulfide (SnS₂) nanosheets are synthesized via hydrothermal method and chemical vapor deposition technique, respectively. The SnS₂nanosheets are directly fabricated on flexible carbon cloth (CC), and then their basal planes are decorated with N-CDs. The as-prepared composite electrodes are used as the counter electrode for the application in dye-sensitized solar cells (DSSCs). The characterizations of N-CDs and SnS₂nanosheets are studied by high resolution transmission electron microscopy, scanning electron microscopic, energy dispersive x-ray spectrometer, Raman spectrometer and x-ray photoelectron spectroscopy etc. Moreover, the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and photocurrent-density voltage are utilized to understand the electro-catalytic performance of N-CDs/SnS₂/CC composite counter electrode. The N-CDs/SnS₂/CC composite electrode shows higher cathodic reduction current density and lower charge transfer resistance in CV and EIS measurements, respectively, as compared to those of the electrodes with N-CDs or SnS₂alone. Meanwhile, the DSSC using N-CDs/SnS₂/CC exhibits cell efficiency (η) of 7.68%, which is higher than those of cells having SnS₂/CC (η= 7.54%) and N-CDs/CC (η= 5.66%) counter electrodes, respectively; it also reaches 94% cell efficiency of the cell using Pt/CC counter electrode (η= 8.15%). The design concept of the modification of the basal planes by defect-rich carbon dots (i.e. N-CDs) and highly-exposed edge sites (i.e. vertically-grown SnS₂nanosheets) makes promising route to enhance the performance of two-dimensional electro-catalysts.

The optothermal Raman method is useful in determining the in-plane thermal conductivity of two-dimensional (2D) materials that are either suspended or supported on a substrate. We compare this method with the Stokes/anti-Stokes scattering thermometry method, which can play a role in both calibration of Raman peak positions as well as extraction of the local phonon temperature. This work demonstrates that the Stokes/anti-Stokes intensity ratio plays an important role in determining the in-plane thermal conductivity of 2D tin diselenide (SnSe₂) dry-transferred onto a polished copper (Cu) substrate. The statistically-averaged thermal conductivity of the 108 ± 24 nm-thick SnSe₂yielded 5.4 ± 3.5 Wm^-1K^-1for the optothermal Raman method, and 2.40 ± 0.81 Wm^-1K^-1for the Stokes/anti-Stokes thermometry method, indicating that the Stokes/anti-Stokes thermometry method to calculate the thermal conductivity of a material can simultaneously increase both precision and accuracy. The uncertainty value was also lowered by a factor of 1.9 from the traditional optothermal Raman method to the Stokes/anti-Stokes thermometry method. The low in-plane thermal conductivity of 2D SnSe₂, 1.3-2.9 times lower than bulk, is useful for applications in thermal and electrical energy conversion and thermoelectric devices.

Two-dimensional M₂C-MXenes, characterized by their lightweight nature, tunable surface structures, and strong affinity for hydrogen, hold significant promise for addressing various challenges in hydrogen energy utilization. This study focuses on investigating the hydrogen adsorption and desorption properties, as well as the stability of hydrogenated compounds in 19 pure M₂C-MXenes nanosheets. The results indicate that hydrogen adsorption on M₂C primarily occurs through weak physisorption, with Mn₂C and Fe₂C from the fourth period, and Ag₂C and Cd₂C from the fifth period exhibiting the lowest adsorption energies. In contrast, hydrogen atoms are adsorbed on M₂C primarily through chemisorption, leading to the potential dissociation of H₂molecules into two hydrogen atoms. Among the M₂C-MXenes, Ti₂C, and Zr₂C in thed⁴andd⁵, respectively, demonstrate the most stable hydrogen atom binding. Hydrogen evolution is most facile on Cu₂C and Ag₂C surfaces. Two types of stacking configurations, face-centered cubic and hexagonal close-packed, are observed for hydrogenated M₂C surfaces (e.g. Co₂C and Zr₂C), showing excellent thermodynamic stability. This work elucidates the hydrogen utilization performance of pure M₂C-MXenes nanosheets and guides future research aimed at achieving high hydrogen storage capacities through the functional tuning of MXenes.

Nanoscale aluminosilicate minerals have wide ranging applications in areas including catalysis, environmental remediation, and medicine. This work reports a reactive laser ablation in liquid (RLAL) synthetic route to aluminosilicate nanominerals that enables facile tuning of their elemental composition, crystallinity, and morphology. Both the precursor solution pH and the choice of base used to adjust the pH were found to determine the properties of the nanominerals produced by laser ablation of a silicon target in aqueous solution of aluminum nitrate. Addition of ammonia produced amorphous phases with fiber- or tube-like morphologies and high aluminum content under alkaline conditions. In contrast, the addition of potassium hydroxide produced highly crystalline quasi-spherical particles, with numerous aluminum silicate and potassium aluminum silicate phases. These results show that manipulation of the precursor solution chemistry for RLAL can produce aluminosilicate nanominerals with a wide range of properties, demonstrating the flexibility of RLAL for synthesis of tailored nanominerals for specific applications.

Graphene exhibits promise in gas detection applications despite its limited selectivity. Functionalization with fluorine atoms offers a potential solution to enhance selectivity, particularly towards ammonia (NH+) molecules. This article presents a study on electron-beam fluorinated graphene (FG) and its integration into gas sensor platforms. We begin by characterizing the thermal stability of fluorographene, demonstrating its resilience up to 450 °C. Subsequently, we investigate the nature of NH₃interaction with FG, exploring distinct adsorption energies to address preferential adsorption concerns. Notably, we introduce an innovative approach utilizing x-ray photoelectron spectroscopy cartography for simultaneous analysis of fluorinated and pristine graphene, offering enhanced insights into their properties and interactions. This study contributes to advancing the understanding and application of FG in gas sensing technologies.

This review focuses on recent progress of wet-chemistry-based synthesis methods for infrared (IR) colloidal quantum dots (CQD), semiconductor nanocrystals with a narrow energy bandgap that absorbs and/or emits IR photos covering from 0.7 to 25 micrometers. The sections of the review are colloidal synthesis, precursor reactivity, cation exchange, doping and de-doping, surface passivation and ligand exchange, intraband transitions, quenching and purification, and future directions. The colloidal synthesis section is organized based on precursors employed: toxic substances as mercury- and lead-based metals and non-toxic substances as indium- and silver-based metal precursors. CQDs are prepared by wet-chemical methods that offer advantages such as precise spectral tunability by adjusting particle size or particle composition, easy fabrication and integration of solution-based CQDs (as inks) with complementary metal-oxide-semiconductors, reduced cost of material manufacturing, and good performances of IR CQD-made optoelectronic devices for non-military applications. These advantages may allow facile and materials' cost-reduced device fabrications that make CQD based IR technologies accessible compared to optoelectronic devices utilizing epitaxially grown semiconductors. However, precursor libraries should be advanced to improve colloidal IR quantum dot synthesis, enabling CQD based IR technologies available to consumer electronics. As the attention of academia and industry to CQDs continue to proliferate, the progress of precursor chemistry for IR CQDs could be rapid.

Semiconducting and metallic nanomaterials are essential building blocks for developing modern-age technologies, and their demand is expanding exponentially with a growing population. However, their processing impacts the ecosystem and requires urgently sustainable solutions. This perspective underlines the emergence of microbe-mediated (bacteria, yeast, fungi, microalgae, viruses, cyanobacteria) green nanomaterials, including metal-based, carbon-based, organic and hybrid nanomaterials, with technical challenges of scalability, stability and cytotoxicity restricting their transition from lab-to-market. Besides, it discusses alternative solutions by integrating digital-age technologies like artificial intelligence to establish these green nano-semiconductors/metals for multidimensional applications and subsidizing the UN's sustainable development goals and one health management.

Nanostructured materials have been suggested to be used as a source of dietary zinc for livestock animals. In this study, we assessed the cytotoxicity of newly synthesized nanostructured zinc carbonate hydroxide (ZnCH) Zn₅(CO₃)(OH)₆microflakes. Cytotoxicity of the microflakes was assessed against murine L929 cell line and rat mature erythrocytes. Viability, motility, cell death pathways, implication of Ca²⁺, reactive oxygen species and reactive nitrogen species (RNS) signaling, caspases, and alterations of cell membranes following exposure of L929 cells to the microflakes were assessed. To assess hemocompatibility of the Zn-containing microflakes, osmotic fragility and hemolysis assays were performed, as well as multiple eryptosis parameters were evaluated. Our findings indicate a dose-response cytotoxicity of ZnCH microflakes against L929 cells with no toxicity observed for low concentrations (10 mg l^-1and below). At high concentrations (25 mg l^-1and above), ZnCH microflakes promoted nitrosyl stress, Ca²⁺- and caspase-dependent apoptosis, and altered lipid order of cell membranes in a dose-dependent manner, evidenced by up to 7-fold elevation of RNS-dependent fluorescence, 2.9-fold enhancement of Fura 2-dependent fluorescence, over 20-fold elevation of caspases-dependent fluorescence (caspase-3, caspase-8, and caspase-9), and up to 4.4-fold increase in the ratiometric index of the NR12S probe. Surprisingly, toxicity to enucleated mature erythrocytes was found to be lower compared to L929 cells. ZnCH microflakes induced eryptosis associated with oxidative stress, nitrosyl stress, Ca²⁺signaling and recruitment of caspases at 25-50-100 mg l^-1. Eryptosis assays were found to be more sensitive than evaluation of hemolysis. Zn₅(CO₃)(OH)₆microflakes show no cytotoxicity at low concentrations indicating their potential as a source of zinc for livestock animals.