scholarly journals Effect of Solvents on Fe–Lignin Precursors for Production Graphene-Based Nanostructures

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2167 ◽  
Author(s):  
Qiangu Yan ◽  
Zhiyong Cai
Keyword(s):  
Electron Microscopy ◽  
Functional Groups ◽  
Solvent Effects ◽  
Iron Particle ◽  
Catalytic Performance ◽  
Kraft Lignin ◽  
Polymer Chains ◽  
Transmission Electron ◽  
Size And Morphology ◽  
Solvated Metal Ions

Kraft lignin was catalytically graphitized to graphene-based nanostructures at high temperature under non-oxidative atmospheres. To obtain the best catalytic performance, a uniform catalyst–lignin mixture must be made by bonding transitional metal (M) ions to oxygen (O), sulfur (S) or nitrogen (N)-containing functional groups in kraft lignin. One of the strategies is to dissolve or disperse kraft lignin in a suitable solvent, whereby the polymer chains in the condensed lignin molecules will be detangled and stretched out while the functional groups are solvated, and when mixing lignin solution with catalyst metal solution, the solvated metal ions in an aqueous solution can diffuse and migrate onto lignin chains to form M-O, M-S, or M-N bonds during the mixing process. Therefore, solvent effects are important in preparing M–lignin mixture for production of graphene-based nanostructures. Fe–lignin precursors were prepared by dissolving lignin with different solvents, including water, methanol, acetone, and tetrahydrofuran (THF). Solvent effects on the catalytic performance, size and morphology of graphene-based nanostructures were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), and nitrogen sorption measurements. The sizes, morphologies, and catalytic properties of the products obtained from Fe–lignin precursors are greatly influenced by the solvents used. It was found that Fe–lignin (THF) had the highest iron dispersion and the smallest iron particle size. Furthermore, Fe–lignin (THF) exhibited the best catalytic performance for graphitization of kraft lignin while the graphitization degree decreased in the order: Fe–lignin(THF) > Fe–lignin(Acetone) > Fe–lignin(methanol) > Fe–lignin(water).

Preferential dissolution along misoriented boundaries in heterogenite

2000 ◽  
Vol 620 ◽  
Author(s):  
R. Lee Penn ◽  
Alan T. Stone ◽  
David R. Veblen
Keyword(s):  
Electron Microscopy ◽  
Aspect Ratio ◽  
Reductive Dissolution ◽  
Morphology Evolution ◽  
Crystal Chemical ◽  
Transmission Electron ◽  
Micron Size ◽  
Primary Particles ◽  
Size And Morphology ◽  
Preferential Dissolution

ABSTRACTHigh-Resolution Transmission Electron Microscopy (HRTEM) results show a strong crystal-chemical and defect dependence on the mode of dissolution of synthetic heterogenite (CoOOH) particles. As-synthesized heterogenite particles are micron-size plates (aspect ratio ∼ 1/30) constructed of crystallographically oriented ∼ 3-nm primary particles or are single ∼ 21-nm unattached heterogenite platelets (aspect ratio ∼1/7). Reductive dissolution, using hydroquinone, was examined in order to evaluate morphology evolution as a function of reductant concentration. Two end-member modes of dissolution were observed: 1) non-specific dissolution of macroparticles and 2) preferential dissolution along misoriented boundaries. In the case of non-specific dissolution, average macrocrystal size and morphology are not altered as building block crystals are consumed. The result is web-like particles with similar breadth and shape as undissolved particles. Preferential dissolution involves the formation of channels or holes along boundaries of angular misorientation. Such boundaries involve only a few degrees of tilt, but dissolution occurs almost exclusively at such sites. Energy-Filtered TEM thickness maps show that the thickness of surrounding material is not significantly different from that of undissolved particles. Finally, natural heterogenite from Goodsprings, Nevada, shows morphology and microstructure similar to those of this synthetic heterogenite.

scholarly journals Enhanced Photocatalytic Activity of Cu2O Cabbage/RGO Nanocomposites under Visible Light Irradiation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1712
Author(s):  
Appusamy Muthukrishnaraj ◽  
Salma Ahmed Al-Zahrani ◽  
Ahmed Al Otaibi ◽  
Semmedu Selvaraj Kalaivani ◽  
Ayyar Manikandan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermo Gravimetric Analysis ◽  
Visible Region ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dye Pollutants ◽  
Transmission Electron

Towards the utilization of Cu2O nanomaterial for the degradation of industrial dye pollutants such as methylene blue and methyl orange, the graphene-incorporated Cu2O nanocomposites (GCC) were developed via a precipitation method. Using Hummers method, the grapheme oxide (GO) was initially synthesized. The varying weight percentages (1–4 wt %) of GO was incorporated along with the precipitation of Cu2O catalyst. Various characterization techniques such as Fourier-transform infra-red (FT-IR), X-ray diffraction (XRD), UV–visible diffused reflectance (UV-DRS), Raman spectroscopy, thermo gravimetric analysis (TGA), energy-dispersive X-ray analysis (EDX), and electro chemical impedance (EIS) were followed for characterization. The cabbage-like morphology of the developed Cu2O and its composites were ascertained from field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HR-TEM). In addition, the growth mechanism was also proposed. The results infer that 2 wt % GO-incorporated Cu2O composites shows the highest value of degradation efficiency (97.9% and 96.1%) for MB and MO at 160 and 220 min, respectively. Further, its catalytic performance over visible region (red shift) was also enhanced to an appreciable extent, when compared with that of other samples.

scholarly journals Structural Characterization of Graphene Oxide: Surface Functional Groups and Fractionated Oxidative Debris

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1180 ◽  
Author(s):  
Elvin Aliyev ◽  
Volkan Filiz ◽  
Muntazim M. Khan ◽  
Young Joo Lee ◽  
Clarissa Abetz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Functional Groups ◽  
Structural Model ◽  
Oxide Surface ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Surface Functional Groups ◽  
X Ray ◽  
Transmission Electron

The purpose of this work is the structural analysis of graphene oxide (GO) and by means of a new structural model to answer the questions arising from the Lerf–Klinowski and the Lee structural models. Surface functional groups of GO layers and the oxidative debris (OD) stacked on them were investigated after OD was extracted. Analysis was performed successfully using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), X-ray photoemission spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, solid-state nuclear magnetic resonance spectroscopy (SSNMR), standardized Boehm potentiometric titration analysis, elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The analysis showed that graphene oxide layers, as well as oxidative debris contain different functional groups such as phenolic –OH, ketone, lactone, carboxyl, quinone and epoxy. Based on these results, a new structural model for GO layers is proposed, which covers all spectroscopic data and explains the presence of the other oxygen functionalities besides carboxyl, phenolic –OH and epoxy groups.

Bioinspired synthesis of self-assembled calcium phosphate nanocomposites using block copolymer-peptide conjugates

2008 ◽  
Vol 23 (12) ◽  
pp. 3196-3212 ◽  
Author(s):  
Yusuf Yusufoglu ◽  
Yanyan Hu ◽  
Mathumai Kanapathipillai ◽  
Matthew Kramer ◽  
Yunus E. Kalay ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Calcium Phosphate ◽  
Small Angle ◽  
Polymer Chains ◽  
X Ray Diffraction ◽  
X Ray ◽  
Self Assembling ◽  
Transmission Electron ◽  
Angle Scattering ◽  
Inorganic Content

Thermoreversibly gelling block copolymers conjugated to hydroxyapatite-nucleating peptides were used to template the growth of inorganic calcium phosphate in aqueous solutions. Nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), transmission electron microscopy, x-ray diffraction, and small-angle scattering were used to characterize these samples and confirm that the peptides promoted the growth of hydroxyapatite as the inorganic phase. Three different polymer templates were used with varying charges on the polymer chains (nonionic, anionic, and zwitterionic), to investigate the role of charge on mineralization. All of the polymer-inorganic solutions exhibited thermoreversible gelation above room temperature. Nanocomposite formation was confirmed by solid-state NMR, and several methods identified the inorganic component as hydroxyapatite. Small angle x-ray scattering and electron microscopy showed thin, elongated crystallites. Thermogravimetric analysis showed an inorganic content of 30–45 wt% (based on the mass of the dried gel at ∼200 °C) in the various samples. Our work offers routes for bioinspired bottom-up approaches for the development of novel, self-assembling, injectable nanocomposite biomaterials for potential orthopedic applications.

CONTROLLED SYNTHESIS OF THE ZnWO4 NANOSTRUCTURE AND STUDY OF THEIR STRUCTURAL AND OPTICAL PROPERTIES

2012 ◽  
Vol 21 (01) ◽  
pp. 1250002 ◽  
Author(s):  
NGUYEN MANH HUNG ◽  
LAM THI HANG ◽  
NGUYEN VAN KHANH ◽  
DU THI XUAN THAO ◽  
NGUYEN VAN MINH
Keyword(s):  
Electron Microscopy ◽  
Grain Size ◽  
Optical Properties ◽  
Reaction Time ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Calcination Time ◽  
Transmission Electron ◽  
Pure Phase ◽  
Size And Morphology

We investigate the effects of calcination time and concentration of solution on the structure, as well as optical properties in ZnWO4 nanopowder prepared by hydrothermal method. The prepared powder were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman scattering, optical absorption and photoluminescent spectroscopy (PL). It is shown that the grain size and morphology of ZnWO4 nanopowder can be controlled by adjusting the reaction time as well as the concentration of the solution. The resultant sample is a pure phase of ZnWO4 without any impurities. The result showed that the optical property of ZnWO4 nanopowders depend on their grain size. The optical band gap becomes narrower as the reaction time or concentration of solution is increased. The improved PL properties of the ZnWO4 crystallites can be obtained with the optimal concentration of the solution.

Synthesis and Characterization of Lead Sulfide Nanostructures with Different Morphologies via Simple Hydrothermal Method

2016 ◽  
Vol 35 (6) ◽  
pp. 559-566 ◽  
Author(s):  
Elaheh Esmaeili ◽  
Mohammad Sabet ◽  
Masoud Salavati-Niasari ◽  
Kamal Saberyan
Keyword(s):  
Electron Microscopy ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
X Ray Diffraction ◽  
Product Size ◽  
X Ray ◽  
Transmission Electron ◽  
Hydrothermal Approach ◽  
Size And Morphology

AbstractPbS nanostructures were synthesized successfully via hydrothermal approach with a new precursor. The products were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–Vis diffuse reflectance spectroscopy (DRS). The effect of different sulfur sources were investigated on product size and morphology.

scholarly journals Catalytic performance of Ag, Au and Ag-Au nanoparticles synthesized by lichen extract

2018 ◽  
Vol 7 (5) ◽  
pp. 433-440 ◽  
Author(s):  
Zafer Çıplak ◽  
Ceren Gökalp ◽  
Bengü Getiren ◽  
Atila Yıldız ◽  
Nuray Yıldız
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fourier Transform ◽  
Catalytic Activity ◽  
Au Nanoparticles ◽  
Bimetallic Nanoparticles ◽  
Catalytic Performance ◽  
Catalytic Activities ◽  
Transmission Electron ◽  
Vis Spectroscopy

Abstract In the present study, the green chemistry approach for the biosynthesis of Ag, Au and Ag-Au bimetallic nanoparticles (NPs) was applied using lichen extract [Cetraria islandica (L.) Ach.]. The lichen extract acts both as a reducing and stabilizing agent. The monometallic and bimetallic NPs were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The results showed that NPs were successfully synthesized and the prepared structures were generally spherical. The synthesized nanostructures exhibited excellent catalytic activities towards reduction of nitrophenols (4-nitrophenol; 4-NP) to aminophenols (4-aminophenol; 4-AP) with sodium borohydride (NaBH4). It was determined that bimetallic NPs exhibit more effective catalytic activity than monometallic Ag and Au nanostructures. This is the first report on 4-NP reduction with Ag, Au and Au-Ag NP catalysts prepared by lichen extract.

Solvothermal Synthesis and Characterization of Lithium Tantalate Nanoparticles

2014 ◽  
Vol 602-603 ◽  
pp. 19-22 ◽  
Author(s):  
Lin Qiang Gao ◽  
Hai Yan Chen ◽  
Zhen Wang ◽  
Xin Zou
Keyword(s):  
Electron Microscopy ◽  
Solvothermal Synthesis ◽  
Room Temperature ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Particle Size And Morphology ◽  
Size And Morphology

Nanoscale LiTaO3 powders with perovskite structure were synthesized using the solvothermal technique with glycol as solvent at 240°C for 12h. The powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD was used to elucidate room temperature structures using Rietveld refinement. The powders were pure single pervoskite phase with high crystallinity. FESEM and TEM were used to determine particle size and morphology. The average LiTaO3 grain size was estimated to be < 200nm, and TEM images indicated that LiTaO3 particles had a brick-like morphology. In addition, the effect of the temperature on the LiTaO3 power characterisitics was also detailed studied.

Preparation of Size and Morphology Controlled Gold Nanoparticles in Micro-Emulsion and in Aqueous

2012 ◽  
Vol 184-185 ◽  
pp. 1138-1141
Author(s):  
Yan Biao Zhang ◽  
Xiao Hui Zhang ◽  
Hong Zong Yin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Light Scattering ◽  
Homogeneous Distribution ◽  
Mass Ratio ◽  
Optimum Ratio ◽  
Transmission Electron ◽  
Micro Emulsion ◽  
Size And Morphology

In this study, we prepared gold nanoparticles in micro-emulsion and found the optimum ratio of micro-emulsion for preparing gold nanoparticles. We reported a new stabilizer for preparing gold nanoparticles in aqueous and found the optimum mass ratio between the stabilizer and chlorauric acid. All gold nanoparticles prepared by these two methods were characterized by transmission electron microscopy, ultraviolet-visible spectrophotometer and synchronous light-scattering spectrophotometer. The results of transmission electron microscopy showed that the diameter range of gold nanoparticles prepared in micro-emulsion was 5~10 nm, and that in aqueous was 10~15 nm. They all had homogeneous distribution and dense structures.

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