scholarly journals Colloidal and Deposited Products of the Interaction of Tetrachloroauric Acid with Hydrogen Selenide and Hydrogen Sulfide in Aqueous Solutions

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 492 ◽  
Author(s):  
Sergey Vorobyev ◽  
Maxim Likhatski ◽  
Alexander Romanchenko ◽  
Nikolai Maksimov ◽  
Sergey Zharkov ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Photoelectron Spectroscopy ◽  
Ex Situ ◽  
Supersaturated Solution ◽  
Hydrodynamic Diameter ◽  
Elemental Selenium ◽  
Potential Measurement ◽  
Gold Colloids ◽  
X Ray ◽  
Vis Spectroscopy

The reactions of aqueous gold complexes with H2Se and H2S are important for transportation and deposition of gold in nature and for synthesis of AuSe-based nanomaterials but are scantily understood. Here, we explored species formed at different proportions of HAuCl4, H2Se and H2S at room temperature using in situ UV-vis spectroscopy, dynamic light scattering (DLS), zeta-potential measurement and ex situ Transmission electron microscopy (TEM), electron diffraction, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Metal gold colloids arose at the molar ratios H2Se(H2S)/HAuCl4 less than 2. At higher ratios, pre-nucleation “dense liquid” species having the hydrodynamic diameter of 20–40 nm, zeta potential −40 mV to −50 mV, and the indirect band gap less than 1 eV derived from the UV-vis spectra grow into submicrometer droplets over several hours, followed by fractional nucleation in the interior and coagulation of disordered gold chalcogenide. XPS found only one Au+ site (Au 4f7/2 at 85.4 eV) in deposited AuSe, surface layers of which partially decomposed yielding Au0 nanoparticles capped with elemental selenium. The liquid species became less dense, the gap approached 2 eV, and gold chalcogenide destabilized towards the decomposition with increasing H2S content. Therefore, the reactions proceed via the non-classical mechanism involving “dense droplets” of supersaturated solution and produce AuSe1−xSx/Au nanocomposites.

scholarly journals Application of Reverse Micelle Sol–Gel Synthesis for Bulk Doping and Heteroatoms Surface Enrichment in Mo-Doped TiO2 Nanoparticles

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 937 ◽  
Author(s):  
Roberto Nasi ◽  
Serena Esposito ◽  
Francesca Freyria ◽  
Marco Armandi ◽  
Tanveer Gadhi ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Reverse Micelle ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Actual State ◽  
Test Reaction ◽  
Potential Measurement ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Mo Content

TiO2 nanoparticles containing 0.0, 1.0, 5.0, and 10.0 wt.% Mo were prepared by a reverse micelle template assisted sol–gel method allowing the dispersion of Mo atoms in the TiO2 matrix. Their textural and surface properties were characterized by means of X-ray powder diffraction, micro-Raman spectroscopy, N2 adsorption/desorption isotherms at −196 °C, energy dispersive X-ray analysis coupled to field emission scanning electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance UV–Vis spectroscopy, and ζ-potential measurement. The photocatalytic degradation of Rhodamine B (under visible light and low irradiance) in water was used as a test reaction as well. The ensemble of the obtained experimental results was analyzed in order to discover the actual state of Mo in the final materials, showing the occurrence of both bulk doping and Mo surface species, with progressive segregation of MoOx species occurring only at a higher Mo content.

The adsorption and dispersing mechanisms of sodium lignosulfonate on Al2O3 particles in aqueous solution

Holzforschung ◽  
2013 ◽  
Vol 67 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Rong Li ◽  
Dongjie Yang ◽  
Wenyuan Guo ◽  
Xueqing Qiu
Keyword(s):  
Metal Cation ◽  
Photoelectron Spectroscopy ◽  
Low Ph ◽  
Repulsive Force ◽  
Sodium Lignosulfonate ◽  
Aggregation State ◽  
Potential Measurement ◽  
X Ray ◽  
Ph Values ◽  
Vis Spectroscopy

Abstract The adsorption behavior and dispersion efficiency of sodium lignosulfonate (NaLS) on Al2O3 particles at different pH values were investigated by UV-Vis spectroscopy, zeta potential measurement, X-ray photoelectron spectroscopy, and viscosity measurements. The effects of the additives urea, Na2SO4, and NaCl were tested. At low pH values, NaLS adsorbed on the Al2O3 particles in the form of aggregates and at high pH values as separated single molecules. At pH 3–11, the adsorption was not affected through addition of urea, ruling out hydrogen bond as a controlling factor. By adding Na2SO4 and NaCl, the main driving force was the synergistic effect of the electrostatic interaction and the metal cation-π interaction at pH<pHIEP (IEP, isoelectric point), whereas the metal cation-π interaction was dominant at pH>pHIEP. The dispersing mechanism was mainly attributed to the steric hindrance (at pH<pHIEP) and the electrostatic repulsive force (at pH>pHIEP) owing to the differences in the aggregation state of the adsorbed molecules.

CO2 Reduction to Propanol by Copper Foams: A Pre- and Post-Catalysis Study

2020 ◽  
Author(s):  
Jennifer A. Rudd ◽  
Ewa Kazimierska ◽  
Louise B. Hamdy ◽  
Odin Bain ◽  
Sunyhik Ahn ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Photoelectron Spectroscopy ◽  
Carbon Capture ◽  
Surface Composition ◽  
Co2 Reduction ◽  
Structural Rearrangement ◽  
Copper Electrode ◽  
Ex Situ ◽  
X Ray ◽  
Copper Electrodes

The utilization of carbon dioxide is a major incentive for the growing field of carbon capture. Carbon dioxide could be an abundant building block to generate higher value products. Herein, we describe the use of porous copper electrodes to catalyze the reduction of carbon dioxide into higher value products such as ethylene, ethanol and, notably, propanol. For <i>n</i>-propanol production, faradaic efficiencies reach 4.93% at -0.83 V <i>vs</i> RHE, with a geometric partial current density of -1.85 mA/cm<sup>2</sup>. We have documented the performance of the catalyst in both pristine and urea-modified foams pre- and post-electrolysis. Before electrolysis, the copper electrode consisted of a mixture of cuboctahedra and dendrites. After 35-minute electrolysis, the cuboctahedra and dendrites have undergone structural rearrangement. Changes in the interaction of urea with the catalyst surface have also been observed. These transformations were characterized <i>ex-situ</i> using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. We found that alterations in the morphology, crystallinity, and surface composition of the catalyst led to the deactivation of the copper foams.

Optimization of Gold Nanoparticles Synthesis using Design of Experiments Technique

2017 ◽  
Vol 68 (7) ◽  
pp. 1518-1423
Author(s):  
Adina Turcu Stiolica ◽  
Mariana Popescu ◽  
Maria Viorica Bubulica ◽  
Carmen Nicoleta Oancea ◽  
Claudiu Nicolicescu ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Zeta Potential ◽  
Design Of Experiments ◽  
Process Model ◽  
Sodium Citrate ◽  
Drug Carriers ◽  
Chloroauric Acid ◽  
Gold Colloids ◽  
Citrate Concentration ◽  
Vis Spectroscopy

Gold nanoparticles are considered the newest drug carriers for different diseases. Therefore it is appropriate continuous optimization of their preparation. In this study, gold colloids with an average size of 1 - 26 nm were obtained by the reduction of tetrachloroauric acid with trisodium citrate. The nanomaterials were characterized by UV-Vis spectroscopy and dynamic light scattering technique. In addition, zeta potential was measured for samples synthesized in order to determine the stability of the colloids. A Two-level Full Factorial design was chosen to determine the optimum set of process parameters (chloroauric acid concentration and sodium citrate concentration) and their effect on various gold nanoparticles characteristics (size and zeta potential). These effects were quantified using Design of Experiments (DoE) with 5 runs and 1 centerpoint. The selected objective and process model in this investigation are screening and interaction. Findings from this research show that to obtain particles larger than 35 nm, it is recommended to increase sodium citrate concentration, at low chloroauric acid values. These conditions will help to achieve smaller zeta potential, too.

scholarly journals Electrochemical study on nickel aluminum layered double hydroxides as high-performance electrode material for lithium-ion batteries based on sodium alginate binder

2021 ◽  
Author(s):  
Xinyue Li ◽  
Marco Fortunato ◽  
Anna Maria Cardinale ◽  
Angelina Sarapulova ◽  
Christian Njel ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Electrode Material ◽  
Photoelectron Spectroscopy ◽  
Negative Electrode ◽  
Lithium Ion ◽  
Electrochemical Study ◽  
Ex Situ ◽  
Potential Range ◽  
X Ray ◽  
Storage Mechanism

AbstractNickel aluminum layered double hydroxide (NiAl LDH) with nitrate in its interlayer is investigated as a negative electrode material for lithium-ion batteries (LIBs). The effect of the potential range (i.e., 0.01–3.0 V and 0.4–3.0 V vs. Li+/Li) and of the binder on the performance of the material is investigated in 1 M LiPF6 in EC/DMC vs. Li. The NiAl LDH electrode based on sodium alginate (SA) binder shows a high initial discharge specific capacity of 2586 mAh g−1 at 0.05 A g−1 and good stability in the potential range of 0.01–3.0 V vs. Li+/Li, which is better than what obtained with a polyvinylidene difluoride (PVDF)-based electrode. The NiAl LDH electrode with SA binder shows, after 400 cycles at 0.5 A g−1, a cycling retention of 42.2% with a capacity of 697 mAh g−1 and at a high current density of 1.0 A g−1 shows a retention of 27.6% with a capacity of 388 mAh g−1 over 1400 cycles. In the same conditions, the PVDF-based electrode retains only 15.6% with a capacity of 182 mAh g−1 and 8.5% with a capacity of 121 mAh g−1, respectively. Ex situ X-ray photoelectron spectroscopy (XPS) and ex situ X-ray absorption spectroscopy (XAS) reveal a conversion reaction mechanism during Li+ insertion into the NiAl LDH material. X-ray diffraction (XRD) and XPS have been combined with the electrochemical study to understand the effect of different cutoff potentials on the Li-ion storage mechanism. Graphical abstract The as-prepared NiAl-NO3−-LDH with the rhombohedral R-3 m space group is investigated as a negative electrode material for lithium-ion batteries (LIBs). The effect of the potential range (i.e., 0.01–3.0 V and 0.4–3.0 V vs. Li+/Li) and of the binder on the material’s performance is investigated in 1 M LiPF6 in EC/DMC vs. Li. Ex situ X-ray photoelectron spectroscopy (XPS) and ex situ X-ray absorption spectroscopy (XAS) reveal a conversion reaction mechanism during Li+ insertion into the NiAl LDH material. X-ray diffraction (XRD) and XPS have been combined with the electrochemical study to understand the effect of different cutoff potentials on the Li-ion storage mechanism. This work highlights the possibility of the direct application of NiAl LDH materials as negative electrodes for LIBs.

Silver mirror reaction metallized chromatography paper for supercapacitor application

2021 ◽  
Author(s):  
I-Hsuan Chen ◽  
Jung-Hsien Chang ◽  
Ren-Jie Xie ◽  
Chia-Hui Tseng ◽  
Sheng-Rong Hsieh ◽  
...  
Keyword(s):  
Flexible Electronics ◽  
Photoelectron Spectroscopy ◽  
Cost Effective ◽  
Water Contact ◽  
X Ray ◽  
Supercapacitor Application ◽  
Resource Limited ◽  
Vis Spectroscopy ◽  
Silver Mirror ◽  
Silver Mirror Reaction

Abstract In this study, the easy-to-operate silver mirror reaction (SMR) was used for metallizing chromatography paper. The SMR-metallized paper was characterized by water contact angle measurements, a surface profiler, X-ray photoelectron spectroscopy, UV-vis spectroscopy, X-ray diffraction, and electrical resistance measurement. The characterization results show that Ag was successfully synthesized on cellulose fibers and was electrically conductive after cyclic bending. Moreover, this SMR-metallized paper was used as electrodes for fabricating a supercapacitor. This SMR-metallized paper could be used for realizing cost-effective flexible electronics applied in on-site biochemical sensing in resource-limited settings.

scholarly journals Microwave synthesis of high-quality and uniform 4 nm ZnFe2O4 nanocrystals for application in energy storage and nanomagnetics

2016 ◽  
Vol 7 ◽  
pp. 1350-1360 ◽  
Author(s):  
Christian Suchomski ◽  
Ben Breitung ◽  
Ralf Witte ◽  
Michael Knapp ◽  
Sondes Bauer ◽  
...  
Keyword(s):  
Energy Storage ◽  
Photoelectron Spectroscopy ◽  
Zinc Ferrite ◽  
Sol Gel ◽  
High Capacity ◽  
Spherical Shape ◽  
Freezing Temperature ◽  
Ex Situ ◽  
Edge Structure ◽  
X Ray

Magnetic nanocrystals with a narrow size distribution hold promise for many applications in different areas ranging from biomedicine to electronics and energy storage. Herein, the microwave-assisted sol–gel synthesis and thorough characterization of size-monodisperse zinc ferrite nanoparticles of spherical shape is reported. X-ray diffraction, 57Fe Mössbauer spectroscopy and X-ray photoelectron spectroscopy all show that the material is both chemically and phase-pure and adopts a partially inverted spinel structure with Fe3+ ions residing on tetrahedral and octahedral sites according to (Zn0.32Fe0.68)tet[Zn0.68Fe1.32]octO4±δ. Electron microscopy and direct-current magnetometry confirm the size uniformity of the nanocrystals, while frequency-dependent alternating-current magnetic susceptibility measurements indicate the presence of a superspin glass state with a freezing temperature of about 22 K. Furthermore, as demonstrated by galvanostatic charge–discharge tests and ex situ X-ray absorption near edge structure spectroscopy, the as-prepared zinc ferrite nanocrystals can be used as a high-capacity anode material for Li-ion batteries, showing little capacity fade – after activation – over hundreds of cycles. Overall, in addition to the good material characteristics, it is remarkable that the microwave-based synthetic route is simple, easily reproducible and scalable.

scholarly journals Microwave-assisted preparation of ZnS and ZnSe nanocrystals with different morphologies for photodegradation process of organic dyes

2019 ◽  
Author(s):  
Katarzyna Matras-Postolek ◽  
A. Zaba ◽  
S. Sovinska ◽  
D. Bogdal
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Organic Dyes ◽  
Zinc Sulphide ◽  
Conventional Heating ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy

Zinc sulphide (ZnS) and zinc selenide (ZnSe) and manganese-doped and un-doped with different morphologies from 1D do 3D microflowers were successfully fabricated in only a few minutes by solvothermal reactions under microwave irradiation. In order to compare the effect of microwave heating on the properties of obtained  nanocrystals, additionally the synthesis under conventional heating was conducted additionally in similar conditions. The obtained nanocrystals were systematically characterized in terms of structural and optical properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-Vis spectroscopy (DR UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. The photocatalytic activity of ZnSe, ZnS, ZnS:Mn and ZnSe:Mn nanocrystals with different morphologies was evaluated by the degradation of methyl orange (MO) and Rhodamine 6G (R6G), respectively. The results show that Mn doped NCs samples had higher coefficient of degradation of organic dyes under ultraviolet irradiation (UV).

scholarly journals Green bio-inspired synthesis, characterization and activity of silver nanoparticle forms of Centaurea virgata Lam. and the isolated flavonoid eupatorin

2018 ◽  
Vol 7 (4) ◽  
pp. 372-379 ◽  
Author(s):  
Burcu Sümer Tüzün ◽  
Judit Hohmann ◽  
Bijen Kivcak
Keyword(s):  
Electron Microscopy ◽  
Zeta Potential ◽  
Synthesis Method ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Characteristic Absorption Band ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Diffraction Patterns ◽  
Isolated Compound

AbstractA green synthesis method of silver nanoparticles (AgNPs) usingCentaurea virgataLam. extract and the isolated compound eupatorin was investigated in this study. Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) spectroscopy, thermal gravimetric analysis, X-ray diffraction analysis and zeta potential were used for characterization of AgNPs. The UV-Vis spectrum exhibited a characteristic absorption band at 420 nm for monodisperse nanoparticles. FTIR measurements also proved the formation. X-ray diffraction patterns showed peaks at (110) and (112), which are characteristic for hexagonal crystals and also showed peaks at (111), (200) and (240), which are characteristic for orthorhombic crystals. The TEM images of AgNPs show that the morphology of AgNPs was predominantly spherical. Obtained AgNPs were highly stable according to the zeta potential values. The nitric oxide scavenging activity, which is also related to anticancer activity, of AgNPs was evaluated. It can be concluded thatC. virgataLam. extract and eupatorin can be used as a reducing agent for potential antioxidant AgNP formation.

Inorganic-Framework Molecularly Imprinted CdS/TiO2 for Selectively Photocatalytic Degradation of Di (2-ethylhexyl) phthalate

2019 ◽  
Vol 41 (2) ◽  
pp. 308-308
Author(s):  
Fangyan Chen Fangyan Chen ◽  
Yiming Liu Yiming Liu ◽  
Xi Zhang Xi Zhang ◽  
Lina He and Yubin Tang Lina He and Yubin Tang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Tetrabutyl Titanate ◽  
Template Molecule ◽  
Molecularly Imprinted ◽  
X Ray ◽  
Simulated Solar Light ◽  
Specific Recognition ◽  
Vis Spectroscopy ◽  
Inorganic Framework ◽  
Ethylhexyl Phthalate

In order to improve the photocatalytic efficiency and selectivity of di (2-ethylhexyl) phthalate (DEHP) under solar-driven, the inorganic-framework molecularly imprinted CdS/TiO2, named as MIP-CdS/TiO2, was prepared by using DEHP as template molecule and tetrabutyl titanate as titanium source and functional monomer. The as-prepared MIP-CdS/TiO2 was characterized by scanning electron microscopy (SEM), X-ray energy spectrum (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis Spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectrum (PL). And the specific recognition and photocatalytic selectivity of MIP-CdS/TiO2 to DEHP were investigated. The results show that inorganic-framework molecular imprinting on the surface of CdS/TiO2 can result in existence of specific recognition sites of DEHP, extend and intensify the absorption visible light of CdS/TiO2, inhibit the recombination of the photo-induced electron-holes pairs. MIP-CdS/TiO2 has a specific recognition to DEHP. The binding selectivity coefficients of DEHP relative to its analogues DBP and DMP are 2.78 and 2.60, respectively. Compared with CdS/TiO2, MIP-CdS/TiO2 exhibits higher photocatalytic activity and selectivity for DEHP. Under simulated solar light irradiation, the degradation efficiency of DEHP photocatalyzed by MIP-CdS/TiO2 is 75.5%, which is 1.63 times as high as that of DEHP photocatalyzed by CdS/TiO2.

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