Lattice Fringe Spacing Research Articles

One-pot synthesis of a CdS–MoS2 / CNTs nano-composite for photocatalytic hydrogen production under visible light

The need to meet growing energy demands of global society in a sustainable fashion requires the development of techniques and processes to reduce dependence on fossil fuels and transit to renewable energy sources. Environmentally benign technologies for alternative fuel production in the form of hydrogen can be developed via heterogenous photocatalysis, a process based on utilization of solar energy. To this end, a cadmium sulfide (CdS) based photocatalyst was developed, doped with MoS2 in a one-pot solvothermal synthesis technique, and coupled with multi-walled carbon nanotubes (MWCNTs) as a carbonaceous support. The material exhibiting the highest rate of hydrogen evolution, CM5C3, involved a MWCNTs loading of 3% and MoS2 loading of 5%. Compared to pure CdS synthesized with the same adapted procedure, the 3% CNT loading improved the rate of hydrogen production by nearly 7-fold, and the optimal 5% MoS2 loading further improved the performance by 60%. CM5C3, achieved an apparent quantum efficiency of 7.34%, a 26-fold increase compared to pure CdS. FESEM and HRTEM imaging confirmed the nanorod-like growth of CdS–MoS2 on the CNT surface, with elemental mapping confirming homogenous dispersion of MoS2 and CNTs. In addition, lattice fringe spacings indicated the presence of cubic and hexagonal CdS growing predominantly along the (111) and (002) planes respectively, in addition to MoS2 distributed throughout the crystal lattice. XRD analysis confirmed the presence of hexagonal and cubic CdS, however, MoS2 phases were not registered perhaps due to the low concentration present in the bulk of the material. XPS survey scans showed the presence of C, Cd, Mo, and S only, with trace oxygen impurities. Peak deconvolution indicated the presence of characteristic peaks for CdS and MoS2, in addition to evidence of the presence of Cd–C bonds, indicating strong CdS heterojunctions to the CNT surface.

Impedance Study of Zinc Sulphide Quantum Dots via One Step Green Synthesis

ZnS quantum dots were synthesized using green synthesis route which are cost effective and eco-friendly. X-ray diffraction study revealed the formation of single phase ZnS. Crystallite size and strain in the as synthesized material were calculated through Williamson-Hall and Size-Strain plot. UV-Vis spectroscopy investigations revealed the absorption region and optical band gap for the ZnS with refractive index analysis. Microstructural analysis of material was done using high resolution transmission electron microscope (HRTEM) which confirms the presence of quantum dots. Selected area electron diffraction pattern (SAEDP) of the corresponding area revealed the polycrystalline nature of as synthesized ZnS with fine crystallites oriented along (111) and (022) planes. Results of analysis of lattice fringe spacing’s of fine crystallites are found to be in good agreement with SAEDP data. Elemental compositional analysis was carried by using EDS as an attachment of TEM which showed the presence of Zinc and Sulphur only. Nyquist plot reported Warburg impedance which suggests the material for solar cell applications.

Lattice Shrinkage of 2D-COFs under Electron Beam Irradiation

Over the past two decades, covalent organic frameworks (COFs) have become the most widely studied porous crystalline materials. Their specific physical and chemical properties are determined by the arrangement of atoms (crystal structure). Therefore, the determination of their structure is arguably the most important characterization step for COFs. Although single-crystal X-ray diffraction is the most widely used method for structure determination, confirmation of the structure of COFs is limited to lattice fringes in transmission electron microscopy (TEM) because of their small crystal size (nanocrystals) or poor crystal quality. At present, many two-dimensional COFs (2D-COFs) have clear powder X-ray diffraction (PXRD) patterns, but specific lattice fringes are not available for all 2D-COFs. This severely hinders the development of the COF field. Here, we discovered the lattice shrinkage behavior of COFs under electron beam irradiation by comparing the lattice fringes of 2D-COFs under different conditions. By comparing the lattice fringes of a 1,3,5-tris-(4-aminophenyl)triazine-1,3,5-tris-(4-formylphenyl)triazine covalent organic framework (TAPT-TFPT COF) at room temperature and under liquid nitrogen freezing conditions, we found that the lattice fringes are in good agreement with the PXRD and the theoretical values of the COF (2.213 nm) under freezing conditions. However, the lattice fringe spacing is only 1.656 nm at room temperature. The discovery not only provides new insights into the TEM characterization of COFs, but also further expands the range of crystalline COF materials.

Nitrogen-Rich Porous Organic Polymers from an Irreversible Amine-Epoxy Reaction for Pd Nanocatalyst Carrier.

Nitrogen-rich porous organic polymers were fabricated through a nonreversible ring-opening reaction from polyamines and polyepoxides (PAEs). The epoxide groups reacted with both primary and secondary amines provided by the polyamines at different epoxide/amine ratios with polyethylene glycol as the solvent to form the porous materials. Fourier-transform infrared spectroscopy confirmed the occurrence of ring opening between the polyamines and polyepoxides. The porous structure of the materials was confirmed through N2 adsorption-desorption data and scanning electron microscopy images. The polymers were found to possess both crystalline and noncrystalline structures, as evidenced by X-ray diffraction and high-resolution transmission electron microscopy (HR-TEM) results. The HR-TEM images revealed a thin, sheet-like layered structure with ordered orientations, and the lattice fringe spacing measured from these images was consistent with the interlayer of the PAEs. Additionally, the selected area electron diffraction pattern indicated that the PAEs contained a hexagonal crystal structure. The Pd catalyst was fabricated in situ onto the PAEs support by the NaBH₄ reduction of the Au precursor, and the size of the nano-Pd was about 6.9 nm. The high nitrogen content of the polymer backbone combined with Pd noble nanometals resulted in excellent catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol.

A Facile and Eco-Friendly Hydrothermal Synthesis of High Tetragonal Barium Titanate with Uniform and Controllable Particle Size.

The preparation of tetragonal barium titanate (BT) powders with uniform and suitable particle sizes is a significant prerequisite for ultra-thin and highly integrated multilayer ceramic capacitors (MLCCs). However, the balance of high tetragonality and controllable particle size remains a challenge, which limits the practical application of BT powders. Herein, the effects of different proportions of hydrothermal medium composition on the hydroxylation process are explored to obtain high tetragonality. The high tetragonality of BT powders under the optimal solvent condition of water:ethanol:ammonia solution of 2:2:1 is around 1.009 and increases with the particle size. Meanwhile, the good uniformity and dispersion of BT powders with particle sizes of 160, 190, 220, and 250 nm benefit from the inhibition of ethanol on the interfacial activity of BT particles (BTPs). The core-shell structure of BTPs is revealed by different lattice fringe spacings of the core and edge and the crystal structure by reconstructed atomic arrangement, which reasonably explains the trend between tetragonality and average particle size. These findings are instructive for the related research on the hydrothermal process of BT powders.

SOĞURMA SPEKTROSKOPİSİ ve GEÇİRİMLİ ELEKTRON MİKROSKOPİ ile KADMİYUM SELENÜR KUANTUM NOKTALARININ OPTİK TESPİTİ

Quantum dots are tiny semiconductor nanocrystals. Their dimensions are between about 2 and 10 nm. They have attracted much attention due to their unique electronic and optical properties. These particles can be synthesized in a variety of ways. Synthesis methods of quantum dots can be classified into top-down and bottom-up. Top-down approach is a fragmentation process of bulk material. In contrast to top-down, quantum dots are constructed from atoms and molecules of the material at bottom-up procedure. Ball milling, optical lithography, laser ablation and arc-discharge are some top-down methods. However, chemical reduction, thermal decomposition, sol-gel and ultrasonic spray pyrolysis are bottom-up methods. In this study, chemical hot-injection synthesis method of cadmium selenide quantum dots which is a kind of bottom-up procedure will be explained. Cadmium selenide quantum dots have been grown in hot solvent at 259oC. Concentration of cadmium selenide quantum dots dispersed in toluene has been adjusted by observing their first exciton peak. First excitonic absorbance peak of cadmium selenide quantum dots has been measured at around 2.18 eV. Transmission electron microscope photo of these growth quantum dots has been shown. The average diameter of cadmium selenide quantum dots has been found to be approximately 3.48 nm. Lattice fringe spacing of cadmium selenide quantum dots has been measured as ~0.35 nm.

Cellulose‐Derived Wearable Carbon Nanoflake Sensors Customized by Semiconductor Laser Photochemistry

AbstractMulti‐functional wearable electrical materials have been regarded as one of the most pivotal cornerstones for the booming internet of things (IoTs), biomimetic robotics/science, and sensory e‐skins. Nevertheless, customizable, high‐throughput, batch‐fabricated, function‐integrated wearable electronics remain technologically challenging to traditional material engineering. Hereby, a cellulose‐converted active amorphous carbon nanomaterial is developed via a transfer‐free, precursor‐free rapid laser synthesis method incorporating deformation‐tolerant waste papers. The lattice fringe spacing of laser‐synthesized carbon nanoflake is ≈0.305 nm topologically distinct from graphene or carbon dots. The nanostructured three‐dimensional (3D) carbon network exhibits desirable mechanical flexibility, high hygroscopicity/electrical conductivity, large ion storing capacity for Zn2+ or Na+, high sensitivity to pressure, and a natural microwave absorbing ratio (> 37 dB at the terahertz range). Abundant percolation pathways inside cellulose/carbon composite networks offered fast electrolyte diffusion and carrier mobility. A series of low‐cost highly‐deformable interdigitated supercapacitors, tactile sensors, electrical circuits, and functional coatings are experimentally fabricated and identified, enabling waste paper as a function‐magnified meta platform for e‐skins, wearable energy devices, or IoTs interfaces.

Prominent bactericidal characteristics of silver-copper nanocomposites produced via pulse laser ablation

This paper reports the characterization and antibacterial performance evaluation of some spherical and stable crystalline silver (Ag)/copper (Cu) nanocomposites (Ag-CuNCs) prepared in deionized water (DIW) using pulse laser ablation in liquid (PLAL) method. The influence of various laser fluences (LFs) on the structural, morphological, optical and antibacterial properties of these NCs were determined. The UV–Vis absorbance of these NCs at 403 nm and 595 nm was gradually increased accompanied by a blue shift. XRD patterns disclosed the nucleation of highly crystalline Ag-CuNCs with their face centered cubic lattice structure. TEM images showed the existence of spherical NCs with size range of 3–20 nm and lattice fringe spacing of approximately 0.145 nm. EDX profiles of Ag-CuNCs indicated their high purity. The antibacterial effectiveness of the Ag-CuNCs was evaluated by the inhibition zone diameter (IZD) and optical density (OD600) tests against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. The proposed NCs revealed the IZD values in the range of 22–26 mm and 20–25 mm when tested against E. coli and S. aureus bacteria, respectively. The Ag-CuNCs prepared at LF of 14.15 J/cm2 revealed the best bactericidal activity. It is established that by controlling the laser fluence the bactericidal effectiveness of the Ag-CuNCs can be tuned.

Some Distinct Attributes of ZnO Nanorods Arrays: Effects of Varying Hydrothermal Growth Time

This study investigates the growth time effect on the structural, morphological, optical, and photoelectrochemical characteristics of highly oriented ZnO nanorod arrays (ZNRAs). The nanorod arrays were grown on ITO substrates using the unified sol-gel spin coating and hydrothermal techniques. ZnO nanoparticles (ZNPs) were synthesized using the sol-gel spin coating method. In contrast, the hydrothermal method was used to grow the ZnO nanorods. The hydrothermal growth time investigated was between 4 and 12 h. The synthesized ZNRAs were used as the photoanode electrodes to investigate their photoelectrochemical (PEC) electrode potency. The as-prepared ZNRAs were characterized using various analytical tools to determine their structures, morphologies, optical, and photoelectrochemical traits. EDX spectra showed the presence of uncontaminated ZnO chemical composition, and FTIR spectra displayed the various functional groups in the samples. A rod-shaped ZnO nanocrystallite with mean lengths and diameters of 300–500 nm and 40–90 nm, respectively, is depicted. HRTEM images indicated the nucleation and growth of ZNRAs with a lattice fringe spacing of 0.26 nm and a growth lattice planer orientation of [002]. The optimum ZNRAs (grown at 8 h) as photoelectrode achieved a photoconversion efficiency of 0.46% and photocurrent density of 0.63 mA/cm2, that was 17 times higher than the one shown by ZNPs with Ag/AgCl as the reference electrode. Both values were higher than those reported in the literature, indicating the prospect of these ZNRAs for photoelectrode applications.

Improved Method for Preparing Nanospheres from Pomelo Peel to Achieve High Graphitization at a Low Temperature

Biomass waste is a valuable resource that can be recovered, reused, and is renewable. However, converting biomass waste to a high degree of order is a bigger challenge, and graphitization at low temperatures is even more difficult. This paper proposes an improved method (Ni element catalysis) for highly graphitizing pomelo peel at low temperatures (750 –900 °C). In this paper, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and high-resolution transmission electron microscopy (HRTEM) were used to study the method and the effect of temperature on structural changes during graphitization. Under the improved method, pomelo peel was transformed into nano-spherical graphitized material. The degree of graphitization reached 80.23% at 900 °C, which was 31.39% higher than that of the traditional method. Furthermore, through HRTEM, the lattice fringe spacing was observed to be 0.337 nm, which is between pure graphite (0.3354 nm) and amorphous graphite (0.3440 nm). In this paper, the improved method can obtain highly graphitized nanospheres at low temperatures, thus reducing energy consumption, reducing environmental pollution, and promoting sustainable development.

Successive Free-Radical C(sp 2 )–C(sp 2 ) Coupling Reactions to Form Graphene

Successive Free-Radical C(sp ² )–C(sp ² ) Coupling Reactions to Form Graphene

An Inorganic–Organic Hybrid Polymer Cocatalyst for Photoelectrochemical Water Oxidation with Dual Functions of Accelerating Kinetics and Improving Charge Transfer

Oxygen evolution cocatalysts (OECs) play important roles in improving the efficiency of photocatalysts in solar water splitting. Inorganic–organic hybrid polymers (IOHPs), which have good electroly...

Mechanistic study on the formation of silicon carbide nanowhiskers from biomass cellulose char under microwave

The paper reports the synthesis of SiC nanowhiskers via a process that utilizes carbon and silica from the same renewable source without the addition of external Si precursors as a sustainable and cost-effective method. This study reports an improved and sustainable method of synthesizing silicon carbide (SiC) nanowhiskers using cornstalk cellulose char under microwave heating. The aim was to optimize the process and gain a deeper understanding of the formation and growth mechanism of SiC nanowhiskers from biomass under microwave treatment in a temperature range of 1200–1400 °C. The synthesized product was then characterized by various analytical techniques. The formation of SiC nanowhiskers (β-SiC) was promoted at higher reaction temperatures, increasing from 6.83 wt% at 1200 °C to 9.35 wt% at 1400 °C. The SiC nanowhiskers displayed straight rod and smooth cylindrical structures. The nanostructure of β-SiC was confirmed along the d-spacing (111) plane, with a characteristic lattice fringe spacing of 0.25 nm. The growth mechanism of the SiC nanowhiskers followed two reaction pathways of vapor-solid (VS) and the vapor-liquid-solid (VLS). Increased CO and CO2 concentrations due to the evolution of gaseous products (SiO and CO) from the reactive cellulose char led to the growth of SiC nanowhiskers under the solid-vapor mechanism. The presence of inherent metallic species, such as Fe in biochar was found to catalyze the formation and growth of SiC nanowhiskers.

Fast Preparation of Ultrafine SiC Crystals from Silicon Cutting Waste and Biomass

In order to reduce the environmental harm of silicon cutting waste (SCW) and increase the value of the plant fiber, we reported a novel method for swiftly preparing ultrafine SiC crystals by spark plasma-assisted silicon–carbon reaction using pretreatment SCW and sisal fibers as raw materials. At 1650 °C, ultrafine SiC crystals with approximately 200 nm grain size were produced. The ultrafine SiC crystals mainly possessed a lattice fringe spacing of 0.25 nm, equivalent to the inter-planar distance between the 3C–SiC (111) planes. The photoluminescence spectrum of the ultrafine SiC crystals exhibited a significant blue shift, indicating that theses crystals are highly valuable for potential future applications in blue-violet emitting devices.

Preparation, characterization, and catalytic performance of Pd–Ni/AC bimetallic nano-catalysts

AbstractPalladium–nickel (Pd–Ni) bimetallic nano-catalysts supported on activated carbon (Pd–Ni/AC) have been successfully prepared by impregnation method enhanced with ultrasonic. The prepared Pd–Ni/AC catalysts were used for the catalytic hydrodechlorination reaction of bleached shellac and characterized by Fourier-transform infrared spectroscopy, nitrogen adsorption, X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscope, and high-resolution transmission electron microscopy. The results show that Pd–Ni bimetallic structures in catalytic particles with the diameter of 4 and 14 nm were distributed uniformly on AC support, and the lattice fringe spacing in catalytic particles was measured as 0.213 nm which is lying in the region between monometallic Pd (111; 0.225 nm) and Ni (111; 0.203 nm), and that Pd1–Ni1/AC catalyst exhibits the best catalytic hydrodechlorination performance with the dechlorination efficiency of 92.58 wt% while it is used for the hydrodechlorination of bleached shellac, and the optimum catalytic performance is related to the synergistic electronic effect and bimetallic structure of the Pd1–Ni1/AC sample.

Customised structural, optical and antibacterial characteristics of cinnamon nanoclusters produced inside organic solvent using 532 nm Q-switched Nd:YAG-pulse laser ablation

Biomedical values of organic natural cinnamon that are buried in their bulk counterpart can be exposed and customised via nanosizing. Based on this factor, a new type of spherical cinnamon nanoclusters (Cin-NCs) were synthesised using eco-friendly nanosecond pulse laser ablation in liquid (PLAL) approach. As-grown nontoxic Cin-NCs suspended in the citric acid of pH 4.5 (acted as organic solvent) were characterised thoroughly to evaluate their structural, optical and bactericidal properties. The effects of various laser fluences (LF) at the fixed wavelength (532 nm) on the physiochemical properties of these Cin-NCs were determined. The FTIR spectra of the Cin-NCs displayed the symmetric-asymmetric stretching of the functional groups attached to the heterocyclic/cinnamaldehyde compounds. The HR-TEM image of the optimum sample revealed the nucleation of the crystalline spherical Cin-NCs with a mean diameter of approximately 10 ± 0.3 nm and lattice fringe spacing around 0.14 nm. In addition, the inhibition zone diameter (IZD) and optical density (OD600) of the proposed Cin-NCs were measured to assess their antibacterial potency against the Staphylococcus aureus (IZD ≈ 24 mm) and Escherichia coli (IZD ≈ 25 mm) bacterial strains. The strong UV absorption (in the range of 269 and 310 nm) shown by these NCs was established to be useful for the antibacterial drug development and food treatment.

Facile self assembly of uniform Cu2Cl(OH)3 nanoflowers and its photo-Fenton degradation performance for dye wastewater

The Cu2Cl(OH)3 uniform nanoflowers (f-Cu) are synthesized by the H2O2-assisted hydrothermal method, and the sample is characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscope (HR-TEM), selected area electron diffraction (SAED), UV–visible diffuse reflectance spectrum (UV-DRS) and Fourier transform infrared (FT-IR). The results show that with the increase of VH2O2/VH2O, the particles have assembled into nanoflowers. Moreover, the Cu2Cl(OH)3 nanoflowers are about 4 μm large, which consist of 5–1000 nm particles. Furthermore, Cu2Cl(OH)3 has monoclinic structure, and the lattice fringe spacing of 0.549 nm matches well with the {1 0 0} planes of Cu2Cl(OH)3, which reveal the single crystalline nature of f-Cu. Moreover, its photo-Fenton reaction degradation performance is evaluated by the decomposition of rhodamine B (RhB) as probing molecule to. It is found that f-Cu may promote the decomposition of H2O2, thus improving photo-Fenton reaction activity; and a low pH value promotes the photo-Fenton reaction. Compared with classic Fenton reaction, the photo-Fenton reaction is efficient at a wider pH range, which is promising for practical application.

Pr0.5Ba0.5Co0.7Fe0.25Nb0.05O3-δ as air electrode for solid oxide steam electrolysis cells

Pr0.5Ba0.5Co0.7Fe0.25Nb0.05O3-δ (PBCFN) is synthesized and evaluated as air electrode for solid oxide steam electrolysis cells (SOECs). X-ray diffraction and TEM analysis show that PBCFN has a pure tetragonal perovskite structure with a lattice fringe spacing of 0.39 nm for the (110) planes. When the applied voltage is set at 1.3 V, a relatively high electrolysis current density of 470 mA cm2 at 800 °C is achieved for electrolyte-supported electrolysis cells with the cell configuration of Sr2Fe1.5Mo0.5O6 (SFM)–Sm0.2Ce0.8O2 (SDC)/La0.8Sr0.2Ga0.87Mg0.13O3 (LSGM)/SDC–PBCFN. In addition, there is no obvious performance degradation during the short-term stability test of the above cells at a constant electrolysis voltage of 1.3 V, indicating that PBCFN is a promising air electrode for SOECs.

Green Synthesis and Characterization of Pullulan Mediated Silver Nanoparticles through Ultraviolet Irradiation.

Nanoparticles (NPs) are, frequently, being utilized in multi-dimensional enterprises. Silver nanoparticles (AgNPs) have attracted researchers in the last decade due to their exceptional efficacy at very low volume and stability at higher temperatures. Due to certain limitations of the chemical method of synthesis, AgNPs can be obtained by physical methods including sun rays, microwaves and ultraviolet (UV) radiation. In the current study, the synthesis of pullulan mediated silver nanoparticles (P-AgNPs) was achieved through ultraviolet (UV) irradiation, with a wavelength of 365 nm, for 96 h. P-AgNPs were formed after 24 h of UV-irradiation time and expressed spectra maxima as 415 nm, after 96 h, in UV-vis spectroscopy. The crystallographic structure was “face centered cubic (fcc)” as confirmed by powder X-ray diffraction (PXRD). Furthermore, high resolution transmission electron microscopy (HRTEM) proved that P-AgNPs were covered with a thin layer of pullulan, with a mean crystalline size of 6.02 ± 2.37. The average lattice fringe spacing of nanoparticles was confirmed as 0.235 nm with quasi-spherical characteristics, by selected area electron diffraction (SAED) analysis. These green synthesized P-AgNPs can be utilized efficiently, as an active food and meat preservative, when incorporated into the edible films.

Solution‐Processed 2D Nb2O5(001) Nanosheets for Inverted CsPbI2Br Perovskite Solar Cells: Interfacial and Diffusion Engineering

Herein, solution‐processed 2D Nb2O5(001) nanosheets (c‐Nb2O5 NS) are prepared and combined with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as an electron transport layer (ETL) for inverted inorganic CsPbI2Br perovskite solar cells (PeSCs). The PeSCs with a c‐Nb2O5/PC61BM bilayer ETL yield a high power conversion efficiency (PCE) up to 11.74%, remarkably outperforming the devices with only PC61BM (9.10%) and those with the state‐of‐the‐art ZnO/C60 ETL (10.65%) prepared under the same conditions. More importantly, the nonencapsulated PeSCs with c‐Nb2O5 exhibit a high thermal stability with only 20% PCE loss after 400 h thermal aging at 85 °C. Such an impressive performance and a high stability can be attributed to the introduction of c‐Nb2O5(001) NS with favorable band levels, strong acid nature, and the small lattice fringe spacing along the large lateral (001) surface, which not only facilitate the electron transport, blocking the hole transport, but also contribute to defect passivation and retard the iodine ions diffusion toward the Ag electrode. This study thus provides a deeper insight for the interfacial design in inverted inorganic PeSCs and contributes to PCE improvement in the future.