Width Of Nanobelts Research Articles

Effects of nanocutting environments on the electronic structure of armchair-type graphene nanoribbons: the first-principles study

In order to investigate the effect of nanocutting environment on the electronic structure of armchair-type graphene nanoribbons, this paper adopts a first-principle computational approach to study the effect of different substrates and solutions, such as on the motion of electrons in the middle and outer orbitals of graphene nanoribbons, by observing the energy band structure, the value of the band gap, and the density of the split-wave states. The results show that the adsorption of Si and C atoms at the edge of the nanoribbon leads to a decrease in the band gap value. The adsorption of Al and O atoms at the edges of graphene nanoribbons leads to a decrease in the nanoribbon band gap value to 0 eV. Different substrate atoms mainly affect the p-orbital electron motion in the nanobelt. Bare-edge graphene nanoribbons are indirect bandgap structures, and graphene nanoribbons with H, O and OH atoms adsorbed at the edges of the nanoribbons are direct bandgap structures. Edge O-isation leads to a nanobelt band gap of 0, which exhibits metallic properties. The edge H-isation nanoribbon band gap is higher than the bare edge nanoribbon band gap. Nanoribbon edge OH-isation reduces the nanoribbon band gap value. Nanoribbon edge adsorption of atoms in solution affects p-orbital electron motion. The formation energy of five-ring defects and seven-ring defects is low, and the defects are easier to form. The edges containing defects all reduce the band gap values of graphene nanoribbons. The defects mainly affect the p-orbital electron motion, leading to differences in the band gap values. The bandgap decreases with increasing nanobelt width, and the bandgap value conforms to 3 N+2<3 N<3 N+1, with regular fluctuations in the curve with period 3. The larger the band gap, the smaller the curvature of the curve at the extremes, and the sparser the curve. In this paper, the electronic structures of different edge structures are analysed from a quantum mechanical point of view, and the synthesis of these results will provide theoretical guidance for obtaining high-quality semiconductor nanoribbons by mechanochemical nanocutting.

Synthesis of polyhedral Pt-Pd-Ni nanobelts regulated by W(CO)6 and applied as a highly performing oxygen reduction reaction electrocatalyst

Pt-Pd-Ni polyhedral nanobelt (PNBs) composite catalysts are synthesized in presence of tungsten hexacarbonyl [W(CO)6] by a simple solvothermal method, combining both higher specific surface area and more index active site than the corresponding single-structure catalysts. The thermal decomposition of W(CO)6 plays a crucial role in the morphology formation. The tenuous composite with a moderate nanobelt width of 7.46 nm formed after heating for 6 h (Pt-Pd-Ni PNBs2) shows better ORR performance and durability than the ternary (Pt-Pd-Ni) and binary (Pt-Pd) single structures. It exhibits a mass activity of 1.49 (A mgPt−1), which only degrades by about 10.63 % after 50,000 durability cycles. The metal regulatory effects induced by the carbonyl compounds cause the contraction of the Pt-Pt bonds. Density functional theory calculations indicate that the compressive strain of Pt-Pd-Ni PNBs2 leads to a decrease in the d-band center and overpotential negatively shifted, thus provide a more sufficient and faster ORR proceeding process in thermodynamics, facilitating a higher energy conversion efficiency.

Influence of Li doping on the morphological evolution and optical & electrical properties of SnO2 nanomaterials and SnO2/Li2SnO3 composite nanomaterials

SnO2 nanomaterials and SnO2/Li2SnO3 composite nanomaterials doped with different Li contents were synthesized via a simple one-step thermal evaporation method. X-ray diffraction patterns showed that with the increase of Li doping, the intensity of Li2SnO3 diffraction peaks gradually increased, while that of SnO2 diffraction peaks gradually decreased. With the increase of Li doping, the width of nanobelts gradually increased, with the morphology changing from banded structure to standard hexagonal sheet structure. The Raman scattering spectra indicated that with the increase of Li doping, the peak of Li2SnO3 at 588.8 cm−1 kept increasing, and the strongest vibration mode A1g in SnO2 gradually weakened. X-ray photoelectron spectroscopy revealed that with the increase of Li doping, the surface electrophilic oxygen species in SnO2/Li2SnO3 composite nanomaterials greatly increased. Under the condition of light irradiation with a wavelength of 505 nm, the bright current of the Li-doped SnO2 samples was higher than the dark current, while that of the SnO2/Li2SnO3 composite nanomaterials was higher than the dark current, which was mainly due to more oxygen vacancies in SnO2/Li2SnO3 composite nanomaterials than electrons excited by light. Consequently, positive photoconductivity gradually weakened, and even the negative photoconductivity emerged.

Phosphorous doped carbon nitride nanobelts for photodegradation of emerging contaminants and hydrogen evolution

Photocatalysis has demonstrated great potentials for both environmental remediation and green energy production. In this study, a simple solvothermal template-free approach was employed for the first time to synthesize phosphorous doped carbon nitride nanobelt (PCNNB). Advanced characterizations, for instance, 13C NMR, 31P NMR, and XPS results indicated that P was substitutionally doped at the corner-carbon of the carbon nitride frameworks. The introduction of P dopants inhibited the polymerization between NH2 groups within PCNNB, enabling the decrease in nanobelt width for the exposure of more active sites. Therefore, the optimized P-CN-NB-2 (derived from 0.2 mM H3PO4) rendered enhanced p-hydroxybenzoic acid (HBA) degradation nearly 66-fold higher than bulk g-C3N4, among the most efficient g-C3N4-based photocatalysts as reported. In addition, the P-CN-NB-1 (derived from 0.02 mM H3PO4) exhibited about 2 times higher H2 evolution rate than CNNB. Density functional theory (DFT) calculations were also conducted to provide insights into the mechanism.

A novel nanostructured supramolecular hydrogel self-assembled from tetraphenylethylene-capped dipeptides.

Herein, we report a tetraphenylethylene-diglycine (TPE-GG) hydrogelator from a systematic study of TPE-capped dipeptides with various amphiphilic properties. From a chemical design, we found that the hydrogelation of TPE-GG molecules can be utilized to generate supramolecular nanostructures with a large TPE-based nanobelt width (∼300 nm) and lateral dimension ratio (>30 fold). In addition, TPE-GG has the lowest molecular weight and minimum number of atoms compared to any TPE-capped peptide hydrogelator reported to date. This minimal self-assembled hydrogelator can fundamentally achieve the gel features compared with other TPE-capped peptides. A combined experimental and computational study indicates the π-π interactions, electrostatic interactions and hydrogen-bonding interactions are the major driving forces behind the formation of self-assembled nanobelts. This study demonstrates the importance of structure-property relationships and provides new insights into the design of supramolecular nanomaterials.

Facile electrospinning fabrication and photoluminescence of LaOI:Tb3+ one-dimensional nanomaterials

LaOI:Tb3+ nanomaterials including nanofibers, nanobelts, and hollow nanofibers were successfully synthesized by electrospinning combined with a double-crucible iodination method using NH4I as iodine source for the first time. X-ray diffractometry analysis revealed that LaOI:Tb3+ nanostructures were phase-pure tetragonal structure with space group of P4/nmm. Scanning electron microscopy analysis showed that the diameters of LaOI:Tb3+ nanofibers, hollow nanofibers and the width of nanobelts were respectively 199.5 ± 30, 376.05 ± 48 nm and 5.2 ± 1.3 μm under the 95 % confidence level. The thickness of the tubewall for hollow nanofibers was 40.5 nm and the thickness of LaOI:Tb3+ nanobelts was 154 nm. Photoluminescence (PL) study demonstrated that the LaOI:Tb3+ nanomaterials exhibited the emission peaks located at 485, 544, 583 and 625 nm, which were ascribed to 5D3 → 7F1, 6, 5D4 → 7F5, 5D4 → 7F4 and 5D4 → 7F3 of energy level transitions of Tb3+, respectively. The PL intensity was strongly affected by the Tb3+-doping concentration, and the optimum quenching concentration was 9 %. The luminescence intensity of LaOI:Tb3+ nanofibers was obviously stronger than that of LaOI:Tb3+ hollow nanofibers and nanobelts under the same measuring conditions. Commission Internationale de L’Eclairage (CIE) analysis demonstrated that the luminescence color of LaOI:9 % Tb3+ nanostructures were located in the green region in CIE chromaticity coordinates diagram. The possible formation mechanisms of LaOI:Tb3+ one dimensional nanomaterials were also proposed.

One-Step Preparation of β-Ga2O3 Nanomaterial and Research the Electrical Transport Properties at High Temperature

Gallium oxide (β-Ga2O3) nanomaterials have been prepared from gallium and oxygen by thermal evaporation in argon atmosphere, and the electrical transport properties have been examined at high Temperature. X-ray diffraction (XRD) reveals that the synthesized products are monoclinic gallium oxide, and it is further confirmed by electron diffraction of transmission electron microscope (TEM). The observation of scanning electron microscope (SEM) reveals that β-Ga2O3 nanobelt width is less than 100 nm and the length is several micrometers. The electricity property was studied at different high Temperatures

Fabrication of Er3+-doped LaOCl nanostructures with upconversion and near-infrared luminescence performances

LaOCl:Er3+ nanofibers and nanobelts were prepared by electrospinning combined with a double-crucible chlorination technique using NH4Cl powders as chlorinating agent. X-ray powder diffraction analysis indicated that LaOCl:Er3+ nanostructures were tetragonal with space group P4/nmm. Scanning electron microscope analysis and histograms revealed that diameter of LaOCl:Er3+ nanofibers and the width of nanobelts respectively were 161.15 ± 18.11 nm and 6.11 ± 0.19 μm under the 95 % confidence level, and the thickness of nanobelts was 116 nm. Up-conversion (UC) emission spectra analysis manifested that LaOCl:Er3+ nanostructures exhibited strong green and red UC emission centering at 525, 548 and 671 nm, respectively attributed to 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4Il5/2 energy levels transitions of Er3+ ions under the excitation of a 980-nm diode laser. It was found that the relative intensities of green and red emissions vary obviously with the changing of concentration of Er3+ ions, and the optimum molar percentage of Er3+/(La3++Er3+) ions was 5 % in the LaOCl:Er3+ nanostructures. The LaOCl:x %Er3+ nanobelts have higher UC emission (both red and green) intensity than the counterpart nanofibers. Moreover, the near-infrared characteristic emissions of LaOCl:Er3+ nanostructures were achieved under the excitation of a 532-nm laser. Commission Internationale de L’Eclairage analysis demonstrated that color-tuned luminescence can be obtained by changing doping concentration of Er3+ ions, which could be applied in the fields of optical telecommunication and optoelectronic devices. The UC luminescent mechanism of LaOCl:Er3+ nanostructures were also proposed.

A Tunable Plasmon Resonance in Gold Nanobelts

Plasmonic nanowires with sub-100-nm rectangular cross sections were found to exhibit a strong transverse plasmon peak at visible wavelengths. By correlating atomic force microscopy measurements of individual nanobelts with their dark-field scattering spectra, it is seen that the transverse peak tunes with cross-sectional aspect ratio. Simulations revealed that the scattering plasmonic modes are transverse antisymmetric excitations across the nanobelt width. Unlike larger diameter silver nanowires, these nanobelts exhibit sharp, tunable plasmon resonances similar to those of nanoparticles.

Size-Controlled Simple Fabrication of Free-Standing, Ultralong Metal Nanobelt Array

Free-standing, ultralong (up to several millimeters) nanobelts of gold, silver, and copper were fabricated by a template approach. Firstly, a metal nanofin array was prepared on a substrate via metal nanocoating of the template surface and selective removal of the metal top layer and template. Electroless plating and sputtering were employed for the metal nanocoating. In this approach, the minimum width and thickness of the Au nanobelt were 95 and 30 nm, respectively. Systematic control of the nanobelt width (from 95 to 350 nm) was successfully achieved by adjusting the template height. Free-standing nanobelts of several millimeters in length were fabricated and maintained their unique structure and alignment, even on a mesh grid.

Synthesis of single-crystal niobium pentoxide nanobelts

In this study, we first developed a simple synthetic route to prepare layered structure NH 4Nb 3O 8 nanobelts, and then converted NH 4Nb 3O 8 phase to single-crystal Nb 2O 5 by thermal treatment in air. The lengths of the nanobelts range from several hundreds of nanometers to several tens of micrometers, and the thickness and width of nanobelts are ∼15 and ∼60 nm, respectively. Based on the experimental results, a possible mechanism for the formation of nanobelts was proposed. Such a simple synthetic route offers great opportunities for the scale-up preparation of one-dimensional nanostructured materials. Furthermore, the synthesized Nb 2O 5 nanobelts were successfully employed, for the first time, as an electrode material in dye-sensitized solar cells using a metal-free idoline dye as a sensitizer and its photovoltaic performance of the solar cells was investigated under illumination of simulated AM 1.5 solar light (100 mW cm −2).

Electrodeposition preparation of ZnO nanobelt array films and application to dye-sensitized solar cells

Abstract ZnO nanobelt array films were prepared using an electrodeposition method with liquid crystal template. The as-prepared sample was amorphous and changed to nanocrystalline ZnO after sintered at 500 °C for 1 h. The sintered film with nanobelt width of about 5 nm was first applied as a photoanode of a dye-sensitized solar cell (DSC), and a high short-circuit photocurrent density of 17 mA/cm 2 and an overall light-to-energy conversion efficiency of 2.6% were achieved.

Synthesis of large-scale GaN nanobelts by chemical vapor deposition

GaN nanobelts were synthesized in mass by direct reaction of metallic gallium with flowing ammonia using nickel as a catalyst. X-ray diffraction, field emission scanning electron microscope equipped with an energy dispersive spectroscopy, and high resolution transmission electron microscopy were used to characterize the products. The results showed that the products are of hexagonal wurtzite structure. The widths of nanobelts were in the range of 50–200nm with the thickness ranging from 3to10nm and their lengths up to several tens of microns. The catalytic growth mechanism of the GaN nanobelts was also discussed.