A super-hydrophobic and super-oleophilic silica film on stainless steel mesh was obtained by simple sol–gel method using tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as precursors. The ...super-hydrophobic and super-oleophilic properties were achieved owing to the hierarchical structure of the silica film with methyl groups terminated domains constructed on the mesh. The effects of the particle size, molar ration of MTES/TEOS, molar concentration of TEOS and aging of the silica sol on the hydrophobicity of the silica film were discussed. With increasing the dimensional size of silica particle, molar ration of MTES/TEOS, molar concentration of TEOS and aging period, the hydrophobicity of the silica film can be enhanced due to the increase of the surface roughness or coverage of the methyl groups. Besides, diiodomethane droplet can spread out on the silica film within 6.71
s for the capillary force and intrinsic oleophilicity of the methyl groups.
In this study, multicomponent Cu
x
O–TiO
2
(
x
= 1 or 2) nanocomposite was used as a photocatalyst to eliminate 2-propanol in gas-phase media under both UV and sunlight-type irradiation. The ...specimens were fabricated by a two-step synthesis including solution treatment–thermal oxidation for Cu
x
O and consequently sol–gel method for applying TiO
2
nanoparticles. The present study focused on analyzing the role of TiO
2
content on the photocatalytic behavior of the Cu
x
O–TiO
2
nanocomposites with varying Ti/Cu atomic ratio. The results showed that the nanocomposite formed successfully in desirable structure and morphology. Moreover, the nanocomposite material having Ti/Cu = 0.6 displayed improved activity concerning both reaction rate and quantum efficiency. Furthermore, it is proved that these nanocomposite materials are stable for photoactivity application. Finally, the kinetic study was carried out with modeling 2-propanol degradation based on the reaction mechanism. The experimental and predicted data obtained under different operational working conditions were in good agreement.
Multicomponent Cu
x
O–TiO
2
nano-photocatalyst was synthesized to eliminate 2-propanol in gas-phase media under both UV and sunlight-type irradiation. The material having Ti/Cu = 0.6 displayed improved activity concerning both reaction rate and quantum efficiency.
Highlights
Cu
x
O–TiO
2
(
x
= 1 or 2) nanocomposite were fabricated by a two-step synthesis method.
Catalysts formed in desirable structure and morphology with different TiO
2
content.
TiO
2
content in the nanocomposite system plays a significant role in photoactivity.
Kinetic study proved the good fitness between experimental and predicted data.
Cu
x
O–TiO
2
composite photocatalysts are stable for photoactivity application.
In this report, undoped, mono and co‐doped perovskite strontium titanate (SrTi1−(x+y)MoxVyO3) were synthesized by the sol‐gel method, and their physical and optical properties were investigated. ...Furthermore, the photocatalytic degradation activities of the synthesized powders were conducted in 10 ppm methylene blue solution under visible‐light irradiation. A maximum degradation efficiency of 91.5% was achieved in SrTi0.9Mo0.05V0.05O3 powder whereas only 59.9% of degradation was found in undoped SrTiO3. The improved efficiency in co‐doped SrTiO3 was due to the doping of metal cations, Mo+6 and V+5 in the host lattice, which created impurity defect states thereby effectively reducing the bandgap energy of the semiconductor.
The present paper reports the synthetic route of Bi2O3 with rod-like architectures and its applications in supercapacitors. The rod-like Bi2O3 was prepared via a sol–gel method using Bi(NO3)3·5H2O as ...a precursor. The structures and morphology of the synthesized samples were characterized by X-ray diffractions (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and nitrogen gas sorption, while their electrochemical properties were carried out using cyclic voltammetry (CV), galvanostatic charge–discharge test and electrochemical impedance spectroscopy (EIS). XRD patterns revealed that the pure β-Bi2O3 phase was obtained and the electrochemical measurement showed that the material exhibited a specific capacitance of 528Fg−1 at the scan rate of 5mVs−1 with superior rate capability. Furthermore, the electrode material shows good cycle stability in the potential range of −1.1 to 0.2V (vs. saturated calomel electrode (SCE)) after 1000 cycles. The results indicate that the as-prepared Bi2O3 is a promising electrode material for pseudocapacitors application.
Zinc oxide nanoparticles (ZnO-NPs) were synthesized via the sol–gel method in gelatin media. Long-chain gelatin compounds were utilized to terminate the growth of ZnO-NPs and to stabilize them. The ...ZnO-NPs were characterized by a number of techniques, such as X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and high-magnification transmission electron microscopy (TEM). The ZnO-NPs calcined at different temperatures exhibited a hexagonal (wurtzite) structure with sizes from 30 to 60
nm. The influence of the calcination temperature on the morphology of ZnO-NPs was also investigated. The results showed that gelatin is an interesting material that can be used as a stabilizer in the sol–gel technique for preparing small ZnO-NPs.
A methodical study on structural, electrical and dielectric properties of NiFeCoO
4
nanoparticles, synthesized via sol-gel technique has been reported in this article. X-ray diffractogram confirmed ...phase purity of the synthesized sample. Raman spectra show the five predicted Raman bands that appear around 600–720, 250–360, 500–590, 450–520 and 180–220 cm
−1
corresponding to A
1g
, E
g
, T
2g
(3), T
2g
(2) and T
2g
(1), respectively. From the dielectric measurements, we have determined the different dielectric parameters such as the conductivity σ
ac
, complex permittivity
ε*
, complex impedance Z*, and the tangent loss (
tanδ
). The electrical properties strongly depend on temperature and frequency. The relaxation activation energy deduced from the Z” vs. frequency plots was similar to the conduction activation energy obtained from the conductivity. Hence, the same type of charge carriers are attributed to the relaxation process and the conduction mechanism. The complex impedance plots have revealed the presence of only one semicircular arc corresponding to grains and grain boundaries contributions at all the temperatures and an equivalent electric circuit was proposed as a model of the sample.
Highlights
The Ni
0.5
Zn
0.5
FeCoO
4
spinel ferrite is synthesized by a sol-gel technique.
The temperature and frequency dependence of dielectric constants have been investigated.
The electrical properties are found to be strongly dependent on temperature and confirmed the presence of one semicircular arc by the Nyquist plots.
The analysis of the thermal variation of the imaginary part of the electrical modulus peak has indicated that the observed relaxation process is thermally activated.
Magnetization measurements (M vs. H) were performed at (T = 300 K) and (T = 10 K) and diverse magnetic parameters comprising Ms (saturation magnetization), Mr (remanence), coercivity (Hc), and so on ...were determined. Smooth M vs. H curves.
Display omitted
•Hard/soft magnetic nanocomposites were prepared via one-pot sol-gel combustion route.•XRD analysis confirmed the co-existence of both hard and soft ferrite phases.•Manifestation of strong exchange-coupling behavior in various prepared composites.•SrCo0.02Zr0.02Fe11.96O19/MnFe2O4 composite exhibits highest exchange-coupling effect.
Hard/soft SrCo0.02Zr0.02Fe11.96O19/MFe2O4 (M = Ni, Co, Cu, Mn and Zn) nanocomposites have been fabricated efficiently via one-pot sol-gel combustion route. The influence of different type of spinel were examined by XRD (X-ray diffraction), SEM – TEM (scanning and transmission electron microscopies) systems and VSM (vibrating sample magnetometer). The XRD investigation of Hard/soft nanocomposites revealed the tailoring between hexaferrite and spinel ferrite phases. Magnetization measurements (M vs. H) were performed at room (T = 300 K) and low temperature (T = 10 K) and diverse magnetic parameters comprising Ms (saturation magnetization), Mr (remanence), coercivity (Hc), and so on were determined. Smooth M vs. H curves and single peaks in dM/dH vs. H plots were observed for various prepared nanocomposites. The Henkel plots and maximum energy products were also determined and analyzed. Various prepared hard/soft nanocomposites indicated relatively high values of diverse magnetic parameters. Diverse findings disclosed the incidence of exchange-coupling spring behavior among various soft and hard magnetic phases. Measurements of ZFC-FC magnetizations showed the existence of a peak temperature values, which are largely ascribed to competition between the motion of magnetic domain walls and thermal activations. It is revealed that one-pot sol-gel combustion route is valuable to attain strong exchange coupling among hard and soft nanoparticle phases grown near to each other. The obtained findings indicated that these nanocomposites are promising candidates for numerous practical applications.
3D graphene frameworks/Co3O4 composites are produced by the thermal explosion method, in which the generation of Co3O4 nanoparticles, reduction of graphene oxide, and creation of 3D frameworks are ...simultaneously completed. The process prevents the agglomeration of Co3O4 particles effectively, resulting in monodispersed Co3O4 nanoparticles scattered on the 3D graphene frameworks evenly. The prepared 3D graphene frameworks/Co3O4 composites used as electrodes for supercapacitor display a definite improvement on electrochemical performance with high specific capacitance (≈1765 F g−1 at a current density of 1 A g−1), good rate performance (≈1266 F g−1 at a current density of 20 A g−1), and excellent stability (≈93% maintenance of specific capacitance at a constant current density of 10 A g−1 after 5000 cycles). In addition, the composites are also employed as nonenzymatic sensors for the electrochemical detection of glucose, which exhibit high sensitivity (122.16 µA mM
−1 cm−2) and noteworthy lower detection limit (157 × 10−9
M, S/N = 3). Therefore, the authors expect that the 3D graphene frameworks/Co3O4 composites described here would possess potential applications as the electrode materials in supercapacitors and nonenzymatic detection of glucose.
A new synthesis routeprovides a new way for the preparation of graphene with macroporous structure. The production of Co3O4 nanoparticles, reduction of graphene oxide, and creation of 3D frameworks are accomplished synchronously. The produced 3D graphene frameworks/Co3O4 composites display excellent electrochemical properties as supercapacitor and exhibit noteworthy performances as nonenzymatic sensors for the electrochemical detection of glucose.
This review presents a brief overview of recent insights into general reaction pathways in sol-gel synthesis of metal oxides. Metal-based sol-gel precursors display kinetically unhindered reactivity, ...combining high reaction speed with reversibility on a molecular level. The process producing metal oxide sols can thus be described as nucleation of an oxide phase with growth option efficiently precluded by extremely low solubility. The emerging nuclei are essentially Polyoxometalate (POM) species, with sizes in the colloid range starting from about 2 nm. They are stabilized in solution by colloid forces (charge interactions, hydrogen bonding, van der Waals forces), defined by the nature and arrangement of species on their surface, which permits them to be denoted as Micelles Templated by Self-Assembly of Ligands (MTSALs). The sol-gel transition occurs on aggregation of particles resulting in percolation. Exploiting this mechanism, it is possible to produce materials with controlled porosity, biocompatibility, and even to access thermodynamically challenging phases that cannot be produced by conventional synthetic techniques.
Graphical Abstract
Metal oxide Sol-Gel can be described as nucleation of an oxide phase resulting from one-step coordination equilibrium in solution, followed by aggregation without growth.
Highlights
Metal alkoxides are strong Brönsted and Lewis bases, undergoing hydrolysis via proton-assisted S
N
1 mechanism
Hydrolysis and polycondensation are for metal alkoxides a single kinetic phenomenon, leading to nucleation of an oxide phase
The metal oxide nuclei are colloid particles 2–5 nm in size with Polyoxometalate structure—a well-ordered core in a shell of ligands, permitting to describe them as Micelles Templated by Self-Assembly of ligands
Li1.5Al0.5Ti1.5(PO4)3 (LATP) has received much attention as a solid electrolyte for lithium ion batteries due to its high Li ion conductivity. In this study, the LATP is prepared by a sol–gel process ...using water-soluble Al(NO3)3 and water-insoluble Al(C3H7O)3 as Al sources to examine the influence of the Al source on the properties of the produced LATP. The LATP is successfully produced in both cases; however, a small amount of AlPO4 impurity is formed in the Al(NO3)3 sample due to insufficient mixing of the water-insoluble Ti(C3H7O)4 with the water-soluble Al(NO3)3. In contrast, the AlPO4 formation is not observed in the Al(C3H7O)3 sample. The Li ion conductivity of the Al(C3H7O)3 sample is higher than that of the Al(NO3)3 sample, implying that the AlPO4 impurity acts as a resistance layer. The performance of LATP prepared by the sol–gel method is strongly affected by the Al sources, and the water-insoluble Al source is suitable for water-insoluble Ti(C3H7O)4, which has been the most widely used Ti source to date.
