Glycol-assisted Sol Gel Research Articles

Correction to: Morphological evolution of 3D ZnO hierarchical nanostructures by diethylene glycol-assisted sol–gel synthesis for highly effective photocatalytic performance

Correction to: Morphological evolution of 3D ZnO hierarchical nanostructures by diethylene glycol-assisted sol–gel synthesis for highly effective photocatalytic performance

Morphological evolution of 3D ZnO hierarchical nanostructures by diethylene glycol-assisted sol–gel synthesis for highly effective photocatalytic performance

Morphological evolution of 3D ZnO hierarchical nanostructures by diethylene glycol-assisted sol–gel synthesis for highly effective photocatalytic performance

A critical study on the magnetic properties of ultrafine cobalt ferrite nanoparticles synthesized by polyethylene glycol assisted sol–gel method

High coercive single-domain CoFe2O4 nanoparticles with the minimal average size (7.6–12.8 nm) were synthesized by polyethylene glycol (PEG) assisted sol–gel method and subsequent annealing at different temperatures. The prepared samples were characterized by XRD, TEM, TG-DSC, and FTIR techniques. The XRD and TEM studies indicated the size and shape of the particles are highly dependent on annealing temperature. Magnetic properties of the developed cobalt ferrite nanoparticles were found to be dependent on their size and shape. The particles annealed at lower temperatures (about 400 °C) are found to be near spherical in shape and as the annealing temperature is increased from 400 to 800 °C, the shape of the particles is observed to be transformed from spherical to octahedron through intermediate cubic shape. Magnetic parameters viz., saturation magnetization (Ms) and remnant magnetization (Mr) exhibited a study increase with increase of the particle size. The coercive field, Hc exhibited a non-monotonic behavior with distinct maximum at about 700 °C and suggested the transition from single-domain to multi-domain state. The magneto-crystalline anisotropy constant, K, determined from Stoner–Wohlfarth relation, exhibited the maximum value, 10.74 × 106 erg/cm3 for the samples annealed at 800 °C. In addition, the magnitude of (BH)max (which is considered as the efficiency of cobalt ferrite nanoparticles for using as permanent magnets) exhibited the maximum value (1.04 × 106 GOe). Such higher values of these two parameters suggest the possible applications of the studied material in magnetic recording, high density digital recording disks and in magnetic sensors.

Ion exchange synthesis of Ag+ incorporated LiAlO2 and its application in photodegradation of organic dyes

The present work aimed at the synthesis, characterization and photodegradation studies of visible light active silver ion (Ag+) incorporated LiAlO2 catalyst. Ethylene glycol assisted sol–gel method was adopted to prepare LiAlO2 at 700 °C. AgAlO2 was synthesized by cation exchange of LiAlO2 by the solid-state method at 300 °C. The structural and optical properties were characterized by powder X-ray diffraction and UV–Vis diffuse reflectance spectroscopy respectively. The scanning electron microscopy (SEM) provided the morphological information of as-prepared samples. LiAlO2 and AgAlO2 were crystallized in a tetragonal lattice (space group P412121) and orthorhombic (space group Pna21) respectively. The bandgap energy of the samples was determined by the Kubelka–Munk (KM) plot. SEM measurements revealed the flower-like hierarchical shape particles. The photocatalytic properties of these samples were evaluated by the degradation of methylene blue and rhodamine B dyes. The mechanistic degradation pathway of RhB was studied using radical quenchers. The rate of recombination of the charge carriers during photocatalysis was discussed.

Polyethylene glycol-assisted sol-gel synthesis of magnetic CoFe2O4 powder as photo-Fenton catalysts in the presence of oxalic acid

The aim of the study was to prepare magnetic photo-Fenton catalysts based on CoFe2O4 by polyethylene glycol-assisted sol-gel method for the degradation of methylene blue under UVA and visible light irradiation with H2C2O4 as a radical producing source. The catalysts were synthesized at different annealing temperatures in order to investigate the influence of annealing temperature on their crystal structure, morphology, surface functional groups, magnetic properties, and their photo-Fenton catalytic activity. According to the results, when the annealing temperature increased from 600 to 800 °C, the content of CoFe2O4 cubic spinel phase was significantly enhanced, the amount of Fe3+ ions in the tetrahedral sites also increased on the surface of samples, which improved the magnetic properties as well as the photo-Fenton catalytic performance under both UVA and visible light. However, at the annealing temperature of 900 °C, the photo-Fenton activity was declined, which can be attributed to the growth of catalytic particles and the decrease of Fe3+ ions on their surface.

Aurivillius family of layered perovskites, BiREWO6 (RE = La, Pr, Gd, and Dy): Synthesis, characterization, and photocatalytic studies

The present work deals with the synthesis, characterization, and photocatalytic studies of layered perovskites belonging to Aurivillius family. Layered perovskites of various chemical compositions, BiREWO 6 (RE = La, Pr, Gd, and Dy), were synthesized by an ethylene glycol–assisted sol–gel method. These materials were characterized by X-ray diffraction, scanning electron microscopy–energy dispersive spectroscopy (EDS), Fourier transform infrared, Raman, and ultraviolet–visible diffuse reflectance techniques. The composition of all these materials was obtained from EDS. The unit cell lattice parameters were attained from Rietveld refinement program, Fullprof.2k, by refining the d-lines of BiREWO 6 . The band gap energy of these samples was obtained from the Kubelka–Munk plot. The photocatalytic activity of all the samples was evaluated by photodegradation of methylene blue. The mechanistic degradation pathway of methylene blue was studied using radical quenchers.

Low temperature synthesis of fluorite-type Ce-based oxides of composition $$\hbox {Ln}_{2}\hbox {Ce}_{2} \hbox {O}_{7}$$ Ln 2 Ce 2 O 7 ( $$\hbox {Ln} = \hbox {Pr}$$ Ln = Pr , Nd and Eu): photodegradation and Luminescence studies

In this work, we have studied the structural behavior of Fluortie-type (F-type) Ce-based oxides of compositions $$\hbox {Ln}_{2}\hbox {Ce}_{2}\hbox {O}_{7}$$ ( $$\hbox {Ln} = \hbox {Pr}$$ , Nd and Eu). F-type oxides can be considered as multi-functional materials due to the deficiency of anions. $$\hbox {Pr}_{2}\hbox {Ce}_{2}\hbox {O}_{7}$$ (PCO), $$\hbox {Nd}_{2}\hbox {Ce}_{2}\hbox {O}_{7}$$ (NCO) and $$\hbox {Eu}_{2}\hbox {Ce}_{2}\hbox {O}_{7}$$ (ECO) were prepared by ethylene glycol-assisted sol–gel method. The structural investigation of these oxides was carried out by Powder XRD and Rietveld refinement. All the materials were found to crystallize in the cubic lattice with space group $$Fm{\overline{3}}m$$ . Raman spectra of these materials are reliable with their XRD data. The morphology and bandgap energy of all the samples were obtained from SEM and KM plot, respectively. The visible light photocatalytic performance of these oxides was examined against the degradation of methylene blue under ambient conditions. The photoluminescence property of the rare earth ions was also studied, and the color coordinates were calculated using CIE 1931 chromaticity. Synopsis Fluorite ( $$\hbox {AO}_{2}$$ , (a)) geometry can be explained as a face centered cubic arrangement of the cations with the anions filling all the tetrahedral spaces with $$Fm{\overline{3}} m$$ space group. Fluorite with one-eighth of anion deficiency leads to P-type oxides with space group $$Fd{\overline{3}}m$$ (b) and C-type oxides with space group Ia3 (c).

Glycol-assisted construction of three-dimensionally ordered macroporous ZnO-Cu2O-TiO2 with enhanced photocatalytic properties

The Zn and Cu bi-components co-modified ZnO-Cu2O-TiO2 composites with 3DOM structure were constructed via a facile glycol-assisted sol–gel method. The morphology, composition and structure of the prepared samples with five different Cu/Zn mass ratios were characterized by XRD, SEM, XPS, UV–VIS DRS and N2 adsorption–desorption. The results indicate that the oxygen vacancies contents of the as-prepared catalysts are heavily dependent on the Cu/Zn mass ratios. Among the five catalysts, the Zn0.06-Cu0.14 sample shows the highest oxygen vacancies content. These findings reveal that the introduction of a certain proportional ZnO and Cu2O can promote the capturing efficiency of visible light and the charge carrier separation, ultimately resulting in an enhanced photodecoloration performance of MB.

Carrier mediated ferromagnetism in Cr doped SrTiO3 compounds

The carrier doped ferromagnetism in SrTiO3 compounds has been investigated for the importance in the field of multiferroics and spintronics. Polycrystalline pure and Cr doped SrTiO3 compounds were synthesized by glycol assisted sol–gel method. Powder X-ray diffraction (XRD) studies reveal the simple cubic perovskite structure of all the prepared compounds. The grain size and lattice strain of the compounds were estimated from the powder XRD pattern which evidences the incorporation of Cr in SrTiO3 system. The local order and disorder parameter of the compounds was investigated by laser Raman spectroscopy. The change in particles to rod like surface morphology while increasing Cr doping concentration was examined by scanning electron microscope and transmission electron microscopy. The enhancement of oxygen vacancy while increasing Cr doping concentration in SrTiO3 system and reduction in Ti4+ to Ti3+ states was identified by X-ray photoelectron spectroscopy. The UV–Vis absorption spectra evidence the distinctive shift of absorption edge exclusively for Cr doped SrTiO3 compounds. Photoluminescence (PL) spectra of the compounds reveal defective states and decrease in PL intensity due to the influence of Cr in SrTiO3. Electron paramagnetic resonance analysis of Cr doped compounds reveals the paramagnetic nature of the dopants. The magnetization studies of all the prepared compounds emphasis carrier mediated diamagnetic to ferromagnetic phase transition in due with the presence of carriers induced by Cr. It is also evident that the highest dopant concentration of Cr in SrTiO3 system exhibits reversal ferromagnetism. The enhancement of magnetization and ferromagnetic ordering has been understood in terms of carrier-mediated Ruderman–Kittel–Kasuya–Yosida interaction theory. The present work also demonstrates the influence of surface morphology on the occurrence of ferromagnetism in Cr doped SrTiO3 compounds.

Solar water-splitting with the defect pyrochlore type of oxides KFe0.33W1.67O6 and Sn0.5Fe0.33W1.67O6·xH2O

Defect pyrochlore of composition KFe0.33W1.67O6 (KFeW) was synthesized by ethylene glycol assisted sol–gel method. The divalent tin doped KFeW (SnFeW) was prepared by ion exchange process using acidified SnCl2. Structural, morphological and optical properties of both materials were characterized by XRD, TGA, SEM-EDS, BET surface analyses and UV–visible diffuse reflectance techniques. The composition of tin-doped KFeW was obtained from EDS and TGA profiles. The cubic lattice parameter 'a' was obtained from Rietveld refinement program, Fullprof.2k, by refining the d- lines of the KFeW. The optical properties of Fe3+ were investigated. Substitution of K+ by Sn2+ led to an absorption shift onset to longer wavelengths. The photocatalytic activities of both samples were evaluated by photodegradation of methylene blue, photooxidation of cyclohexene and solar water-splitting reactions. The mechanistic degradation pathway of methylene blue (MB) was studied in the presence of both photocatalysts.

Optical, electrical, and photocatalytic properties of polyethylene glycol-assisted sol–gel synthesized BaTiO3@ZnO core–shell nanoparticles

BaTiO3@ZnO core–shell nanoparticles were synthesized by sol–gel method using polyethylene glycol (PEG) 4000 (4k) and 20,000 (20k). The powder X-ray diffractograms and energy dispersive X-ray spectra confirm the core–shell nature of the prepared nanoparticles. While the use of PEG 20k instead of PEG 4k increased the interplanner distances in ZnO of BaTiO3@ZnO core–shell nanoparticles it decreased the d-spacing in sol–gel synthesized pristine ZnO nanoparticles. The diffuse reflectance spectra of BaTiO3@ZnO core–shell nanoparticles are similar to those of ZnO nanoparticles. So are the photoluminescence (PL) spectra. The charge transfer resistances of BaTiO3@ZnO core–shell nanoparticles are larger than those of pristine ZnO nanoparticles. The PEG-assisted sol–gel prepared BaTiO3@ZnO core–shell nanoparticles are better photocatalysts than the PEG-assisted sol–gel synthesized pristine ZnO nanoparticles.

Electrical, optical and photocatalytic properties of polyethylene glycol-assisted sol–gel synthesized Mn-doped TiO2/ZnO core–shell nanoparticles

Spherically shaped Mn-doped TiO2/ZnO core–shell nanoparticles have been synthesized by sol–gel method using polyethylene glycol (PEG) 4,000 or 20,000 as template. The powder X-ray diffractograms and energy dispersive X-ray, UV–visible diffuse reflectance and photoluminescence spectra confirm the ZnO shell in the synthesized core–shell nanoparticles. The charge-transfer resistance of the core–shell nanoparticles is less than that of pristine ZnO nanoparticles. The synthesized Mn-doped TiO2/ZnO nanoparticles are better photocatalysts than Mn-doped TiO2.

Facile synthesis of cookies-shaped LiV3O8 cathode materials with good cycling performance for lithium-ion batteries

Cookies-shaped LiV3O8 materials were successfully synthesized by a facile ethylene glycol-assisted sol–gel method. The LiV3O8 compound fabricated at 550 °C delivers an initial specific discharge capacity of 255.2 mAh g−1 between 2.0 and 4.0 V at a current density of 50 mA g−1, and possesses a capacity retention of 90.2% after 50 cycles and up to 85% at a current density of 120 mA g−1 after 100 cycles. Furthermore, the compound with a proper particle size and high crystallinity also shows high electrochemical reversibility and structural stability, leading good rate capability. By analysis of inductively coupled plasma emission spectrometer (ICP), the cookies-like LiV3O8 has very little dissolution of vanadium in the electrolyte after 100 cycles, indicating that the well-formed crystal can protect the structure damage to some degree during cycling.

Synthesis, Photocatalytic and Electrocatalytic Activities of Wormlike GdFeO3 Nanoparticles by a Glycol-Assisted Sol–Gel Process

Wormlike GdFeO3 (GFO) nanoparticles were synthesized by a glycol-assisted sol–gel rapid calcination process. The as-synthesized GdFeO3 was characterized by X-ray diffraction, transmission electron microscopy, differential scanning calorimeter and thermogravimetric analysis, Fourier transformed infrared spectroscopy, and UV–vis absorption spectroscopy. The visible-light-responsive photocatalytic activity of GdFeO3 nanoparticles was evaluated by the photodegradation of Rhodamine B under visible light. The synergism of semiconductor-photocatalyzed oxidation and heterogeneous photo-Fenton-like reaction can markedly promote the photodegradation with a booming catalytic activity (k = 1.2814 h–1). Compared with the bulk, the catalytic activity of the GFO–H2O2 system was improved about 80 times. Meanwhile, the glass carbon electrode decorated with the resulting nanoparticles was used to examine the electrocatalytic behavior for p-nitrophenol reduction in a basic solution. The results show the obtained GdFeO3 nanoparticles with excellent photocatalytic and electrocatalytic activities.

Preparation of a visible light-driven Bi2O3–TiO2 composite photocatalyst by an ethylene glycol-assisted sol–gel method, and its photocatalytic properties

A visible light-driven Bi2O3–TiO2 composite photocatalyst was prepared by an ethylene glycol-assisted sol–gel method in which ethylene glycol acted as a polycondensation agent to capture metal ions by reacting with bismuth and titanium sources via a complex polycondensation pathway. The photocatalyst was characterized by X-ray photoelectron spectroscopy, X-ray diffraction, acquisition of N2 adsorption–desorption isotherms, transmission electron microscopy, and UV–visible diffuse reflectance spectroscopy. The results revealed that the Bi2O3–TiO2 composite was of smaller particle size, greater specific surface area, and had stronger absorbance in the visible light region than pure TiO2. The photocatalytic activity of the as-prepared catalyst was evaluated by degradation of rhodamine B under visible light irradiation (λ > 400 nm); the as-prepared Bi2O3–TiO2 composite was substantially more active than pure TiO2. This was ascribed to the high surface area and the heterojunction structure.

Photocatalytic bacteria inactivation by polyethylene glycol-assisted sol–gel synthesized Cd-doped TiO2 under visible light

Cd-doped TiO2 nanoparticles have been obtained by polyethylene glycol-assisted sol–gel synthesis and characterized by powder X-ray diffraction, energy dispersive X-ray analysis, high-resolution scanning electron microscopy and UV–visible diffuse reflectance, photoluminescence and impedance spectroscopies. Use of polyethylene glycol as templating agent provides club-shaped particles. Doping TiO2 with Cd decreases the average crystallite size and charge transfer resistance, increases the capacitance, and leads to blue emission. Cd-doping enhances the visible light photocatalytic disinfection of bacteria but not dye degradation.