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

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.

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SiO2 Coated Li-rich Layered Oxides-Li1.2Ni0.13Mn0.54Co0.13O2 for efficient energy storage applications

University of the Future: Re-Imagining Research and Higher Education ◽

10.29117/quarfe.2020.0005 ◽

2020 ◽

Author(s):

Jeffin James Abraham ◽

Umair Nisar ◽

Haya Monawwar ◽

Aisha Abdul Quddus ◽

Abdul Shakoor ◽

...

Keyword(s):

Energy Storage ◽

Photoelectron Spectroscopy ◽

Sol Gel ◽

Lithium Ion ◽

Side Reactions ◽

Electrochemical Performances ◽

Layered Oxides ◽

Capacity Retention ◽

Pure Material ◽

X Ray

Lithium ion batteries (LIBs) are attractive for energy storage application. In this regard, lithium rich layered oxides (LLOs), are considered viable cathodes due to their tempting properties such as lower production cost, faster manufacturing process, excellent reversible capacity, and better electrochemical performance at high voltages. Despite these properties, LLOs lack in cyclic stability and inferior capacity retention. This study proposes a surface modification technique to overcome the above-mentioned limitations in which a layer of silica (SiO2) has been coated on the particles of Li1.2Ni0.13Mn0.54Co0.13O2. The Li1.2Ni0.13Mn0.54Co0.13O2 was synthesized by a sol-gel process and then coated with SiO2 (SiO2=1.0 wt. %, 1.5 wt. %, and 2.0 wt. %). The coatings were undertaken through a dry ball milling technique. Different characterization test such as X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), elemental mapping, and X-ray photoelectron spectroscopy (XPS), were utilized to prove phase pure material formation and identify the SiO2 layer on the surface of Li1.2Ni0.13Mn0.54Co0.13O2. The electrochemical measurements, confirm the improvement in capacity retention and cyclability of SiO2 coated Li1.2Ni0.13Mn0.54Co0.13O2 samples with reference to the uncoated samples. This improvement can be ascribed to the protective and barrier effect of the coated layer on the LLOs particles avoiding any unwanted side reactions when the cathode is exposed to the electrolyte. A small trade-off between electrochemical performances and the coating thickness confirms the best efficiency of 1 wt.% SiO2 coated Li1.2Ni0.13Mn0.54Co0.13O2 when compared to other coated samples.

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Synthesis of Mn-Doped ZnS Nanoparticles and Its Characterization

Journal of Nanoelectronics and Optoelectronics ◽

10.1166/jno.2020.2711 ◽

2020 ◽

Vol 15 (1) ◽

pp. 65-70

Author(s):

F. F. Al-Harbi

Keyword(s):

Photoelectron Spectroscopy ◽

Sol Gel ◽

Spherical Shape ◽

Visible Range ◽

Photoluminescence Properties ◽

X Ray Diffraction ◽

Zns Nanoparticles ◽

X Ray ◽

Crystallite Sizes ◽

Mn Doped

ZnS powders doped with manganese (ZnS:Mn) was synthesized by the sol gel method. The structural and optical characteristics are studied using various techniques. Analysis with X-ray diffraction shows that cubic ZnS phase is formed with average crystallite sizes varying between 10 nm and 13 nm. There is no phase transformation due to Mn2+ doping. The formation of ZnS was confirmed by X-ray photoelectron spectroscopy (XPS) measurement. TEM images indicated the spherical shape of the nanoparticles. However, optical study has shown a strong reflectance in the visible range. The band gap (Eg) of ZnS:Mn is varied between 3.51 eV and 3.56 eV. The photoluminescence properties of ZnS:Mn nanopowders were studied.

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Characterization of Photoactive Fe-TiO2 Lime Coatings for Building Protection: The Role of Iron Content

Materials ◽

10.3390/ma12111847 ◽

2019 ◽

Vol 12 (11) ◽

pp. 1847 ◽

Cited By ~ 5

Author(s):

Chrysi Kapridaki ◽

Nikolaos Xynidis ◽

Eleftheria Vazgiouraki ◽

Nikolaos Kallithrakas-Kontos ◽

Pagona Maravelaki-Kalaitzaki

Keyword(s):

Tio2 Nanoparticles ◽

Photoelectron Spectroscopy ◽

Sol Gel ◽

Nitrogen Adsorption ◽

Visible Radiation ◽

Edge Structure ◽

Doped Tio2 ◽

X Ray ◽

Vis Spectroscopy

Iron-doped TiO2 nanoparticles, ranging in Fe concentrations from 0.05 up to 1.00% w/w, were synthesized through a simple sol-gel method. Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Ultraviolet-Visible (UV-Vis) spectroscopy, nitrogen adsorption−desorption isotherms, X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure spectroscopy (XANES) were used to characterize the synthesized nanoparticles. The characterization of the Fe-doped TiO2 nanoparticles revealed the predominant presence of anatase crystalline form, as well as the incorporation of the Fe3+ ions into the crystal lattice of TiO2. The photocatalytic assessment of the Fe-doped TiO2 nanoparticles indicated that the low iron doping titania (0.05 and 0.10% w/w) have a positive effect on the photocatalytic degradation of Methyl Orange under visible radiation. Moreover, FTIR monitoring of calcium hydroxide pastes enriched with low Fe-doped TiO2 revealed enhancement of carbonation at both early and later stages. Improved photocatalytic performance and increased lime carbonation, observed in lime coatings with low Fe-doped TiO2 admixtures, established them as invaluable contributors to the protection of the built environment.

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Microencapsulation of stearic acid with SiO2 shell as phase change material for potential energy storage

Scientific Reports ◽

10.1038/s41598-020-71940-9 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Shafiq Ishak ◽

Soumen Mandal ◽

Han-Seung Lee ◽

Jitendra Kumar Singh

Keyword(s):

Energy Storage ◽

Stearic Acid ◽

Phase Change ◽

Phase Change Material ◽

Photoelectron Spectroscopy ◽

Sol Gel ◽

Scanning Calorimetry ◽

X Ray ◽

Sio2 Shell ◽

Change Material

Abstract Stearic acid (SA) is being used as phase change material (PCM) in energy storage applications. In the present study, the microencapsulation of SA with SiO2 shell was carried out by sol–gel method. Different amounts of SA (5, 10, 15, 20, 30 and 50 g) were taken against 10 ml of tetraethyl orthosilicate (TEOS) for encapsulation. The synthesized microencapsulated PCM (MEPCM) were characterized by Fourier transform infrared spectroscope (FT-IR), X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The characterization results showed that SA was successfully encapsulated by SiO2. Thermogravimetric analysis (TGA) exhibited better thermal stability of the MEPCM than SA. The enthalpy values of MEPCM were found to be unchanged even after 30 heating–cooling cycles by differential scanning calorimetry (DSC). The latent heats of melting and solidification of 50 g SA containing MEPCM were found to be highest i.e. 182.53 J/g and 160.12 J/g, respectively among all microencapsulated samples. The encapsulation efficiency values were calculated using thermal data and the efficiency was found to be highest i.e. 86.68% in the same sample.

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Development of an Adsorbing System Made of DMS-1 Mesh Modified by Amino Groups to Remove Pb(II) Ions from Water

Materials ◽

10.3390/ma13081914 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1914

Author(s):

Viviana Palos-Barba ◽

Cecilia Lugo-Nabor ◽

Rodrigo R. Velázquez-Castillo ◽

Dora Alicia Solís-Casados ◽

Carmen L. Peza-Ledesma ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Low Cost ◽

Sol Gel ◽

Nitrogen Adsorption ◽

Good Alternative ◽

Ex Situ ◽

Amino Groups ◽

X Ray ◽

Molar Ratios ◽

Adsorption Processes

Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal was to determine the adsorption capacity of a Disordered Mesoporous Silica 1 material (DMS-1) functionalized with amino groups, for Pb(II) ions removal. DMS-1 was prepared by sol-gel method and the incorporation of amino groups was performed by ex-situ method. As the source of amine groups, (3-Aminopropyl) triethoxysilane (APTES) was used and three different xNH2/DMS-1 molar ratios (0.2, 0.3, 0.4) were evaluated. In order to evaluate the incorporation of the amino group into the mesopore channels, thermal and structural analysis were made through Thermogravimetric Analysis (TGA), nitrogen adsorption–desorption at 77 K by Specific Brunauer–Emmett–Teller (SBET) method, Fourier Transfer Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). The higher Pb(II) ions removal was achieved with the 0.3 molar proportion of xNH2/DMS-1 reaching 99.44% efficiency. This result suggests that the functionalized material can be used as an efficient adsorbent for Pb(II) ions from aqueous solution.

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

10.26434/chemrxiv.12022623.v1 ◽

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 n-propanol production, faradaic efficiencies reach 4.93% at -0.83 V vs RHE, with a geometric partial current density of -1.85 mA/cm2. 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 ex-situ 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.

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

Journal of Solid State Electrochemistry ◽

10.1007/s10008-021-05011-y ◽

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.

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Enhanced Photocatalytic Activity of CuWO4 Doped TiO2 Photocatalyst Towards Carbamazepine Removal under UV Irradiation

Separations ◽

10.3390/separations8030025 ◽

2021 ◽

Vol 8 (3) ◽

pp. 25

Author(s):

Chukwuka Bethel Anucha ◽

Ilknur Altin ◽

Emin Bacaksız ◽

Tayfur Kucukomeroglu ◽

Masho Hilawie Belay ◽

...

Keyword(s):

Electron Microscopy ◽

Photocatalytic Activity ◽

Photoelectron Spectroscopy ◽

Diffuse Reflectance Spectroscopy ◽

Sol Gel ◽

Pure Tio2 ◽

Component Part ◽

Energy Yield ◽

Mechanical Agitation ◽

X Ray

Abatement of contaminants of emerging concerns (CECs) in water sources has been widely studied employing TiO2 based heterogeneous photocatalysis. However, low quantum energy yield among other limitations of titania has led to its modification with other semiconductor materials for improved photocatalytic activity. In this work, a 0.05 wt.% CuWO4 over TiO2 was prepared as a powder composite. Each component part synthesized via the sol-gel method for TiO2, and CuWO4 by co-precipitation assisted hydrothermal method from precursor salts, underwent gentle mechanical agitation. Homogenization of the nanopowder precursors was performed by zirconia ball milling for 2 h. The final material was obtained after annealing at 500 °C for 3.5 h. Structural and morphological characterization of the synthesized material has been achieved employing X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) N2 adsorption–desorption analysis, Scanning electron microscopy-coupled Energy dispersive X-ray spectroscopy (SEM-EDS), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy (UV-vis DRS) for optical characterization. The 0.05 wt.% CuWO4-TiO2 catalyst was investigated for its photocatalytic activity over carbamazepine (CBZ), achieving a degradation of almost 100% after 2 h irradiation. A comparison with pure TiO2 prepared under those same conditions was made. The effect of pH, chemical scavengers, H2O2 as well as contaminant ion effects (anions, cations), and humic acid (HA) was investigated, and their related influences on the photocatalyst efficiency towards CBZ degradation highlighted accordingly.

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Synthesis, characterization and in vitro cytotoxicity study of Co and Ni ferrite nanoparticles prepared by sol-gel method

SN Applied Sciences ◽

10.1007/s42452-021-04709-y ◽

2021 ◽

Vol 3 (7) ◽

Author(s):

Alexandre Pancotti ◽

Dener Pereira Santos ◽

Dielly Oliveira Morais ◽

Mauro Vinícius de Barros Souza ◽

Débora R. Lima ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Sol Gel ◽

Test Sample ◽

In Vitro Cytotoxicity ◽

Gel Method ◽

X Ray ◽

Sol Gel Method ◽

Transmission Electron ◽

Crystallite Sizes

AbstractIn this study, we report the synthesis and characterization of NiFe2O4 and CoFe2O4 nanoparticles (NPs) which are widely used in the biomedical area. There is still limited knowledge how the properties of these materials are influenced by different chemical routes. In this work, we investigated the effect of heat treatment over cytotoxicity of cobalt and niquel ferrites NPs synthesized by sol-gel method. Then the samples were studied using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), Fourier Transform Infrared Spectroscopy Analysis (FTIR), and X-ray fluorescence (XRF). The average crystallite sizes of the particles were found to be in the range of 20–35 nm. The hemocompatibility (erythrocytes and leukocytes) was checked. Cytotoxicity results were similar to those of the control test sample, therefore suggesting hemocompatibility of the tested materials.

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