The chemical protonation of graphitic carbon nitride (CN) solids with strong oxidizing acids, for example HNO3, is demonstrated as an efficient pathway for the sol processing of a stable CN colloidal ...suspension, which can be translated into thin films by dip/disperse‐coating techniques. The unique features of CN colloids, such as the polymeric matrix and the reversible hydrogen bonding, result in the thin‐film electrodes derived from the sol solution exhibiting a high mechanical stability with improved conductivity for charge transport, and thus show a remarkably enhanced photo‐electrochemical performance. The polymer system can in principle be broadly tuned by hybridization with desired functionalities, thus paving the way for the application of CN for specific tasks, as exemplified here by coupling with carbon nanotubes.
Going strong: Sol engineering of graphitic carbon nitride solids with strong oxidizing acids (e.g. HNO3) generates a stable colloidal suspension, which can be translated into thin films by dip/disperse‐coating techniques. The polymeric matrix and the reversible hydrogen bonding result in the thin‐film electrodes derived from the sol solution having high mechanical stability with improved conductivity for charge transport.
This work aims to prepare a series of sols based on Titanium (IV) butoxide (TBT) and using boric acid as a functional additive. The sols were applied onto the cotton fabric by the pad-pry-cure ...process. The as-obtained cotton fabrics were characterized using Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis in order to determine their chemical composition and their surface morphology, respectively. The results indicate the formation of TiO
2
–boron-based coating over the surface of coated cotton fabric. X-ray diffraction (XRD) patterns showed that the coating did not affect the crystallographic structure of the cellulosic fabric. The functional properties of the treated samples were measured from thermo-oxidative stability and burning behavior performance, drop absorption and water uptake measurements. The results showed that the coated cotton fabrics by the sol–gel approach through the application of TiO
2
–boron-based coating with 2.5 molar ratio of boric acid possessed high thermal stability and flame retardancy. Most importantly, a total burning time of 2 s and a residue of more than 90% were obtained after 10 s of flame application, indicating that the functionalized cotton fabric self-extinguished the fire rapidly. The water-repellent properties were also enhanced and the obtained results mentioned that the drop time and the water uptake were improved compared with untreated cotton fabric. The effect of the application of TiO
2
–boron-based coatings on the mechanical properties of cotton samples, as well as their washing fastness were studied.
Highlights
A series of sols based on Titanium (IV) butoxide and boric acid have been synthesized at a different molar ratio of boric acid from 0.1 to 2.5.
The prepared sols were applied to the surface of the cotton fabric by the pad-dry-cure process.
The production of cotton fabric with flame-retardant (FR) and hydrophobic properties through the application of TiO
2
–boron-based coating has been successfully achieved.
Good flame-retardant property and thermal stability, as well as, water repellence of modified cotton fabric, were found at 2.5 molar ratio of boric acid.
The development of biomaterials with intrinsic antioxidant properties could represent a valuable strategy for preventing the onset of peri-implant diseases. In this context, quercetin, a naturally ...occurring flavonoid, has been entrapped at different weight percentages in a silica-based inorganic material by a sol-gel route. The establishment of hydrogen bond interactions between the flavonol and the solid matrix was ascertained by Fourier transform infrared spectroscopy. This technique also evidenced changes in the stretching frequencies of the quercetin dienonic moiety, suggesting that the formation of a secondary product occurs. Scanning electron microscopy was applied to detect the morphology of the synthesized materials. Their bioactivity was shown by the formation of a hydroxyapatite layer on sample surface soaked in a fluid that simulates the composition of human blood plasma. When the potential release of flavonol was determined by liquid chromatography coupled with ultraviolet and electrospray ionization tandem mass spectrometry techniques, the eluates displayed a retention time that was 0.5 min less than quercetin. Collision-activated dissociation mass spectrometry and untraviolet-visible spectroscopy were in accordance with the release of a quercetin derivative. The antiradical properties of the investigated systems were evaluated by DPPH and ABTS methods, whereas the 2,7-dichlorofluorescein diacetate assay highlighted their ability to inhibit the H
2
O
2
-induced intracellular production of reactive oxygen species in NIH-3T3 mouse fibroblast cells. Data obtained, along with data gathered from the MTT cytotoxicity test, revealed that the materials that entrapped the highest amount of quercetin showed notable antioxidant effectiveness.
•ZnO–SnO2 nanocomposites were prepared by a facile sol–gel synthesis.•The photoactivity of the samples was studied using the degradation of 4-nitrophenol.•The photocatalytic activity depended on the ...ZnO/SnO2 molar ratio.•The high photoactivity was attributed to the presence of heterojunctions ZnO–SnO2.•The sol–gel-prepared nanocomposites showed a superior photoactivity.
ZnO–SnO2 nanocomposites were synthesized by a facile sol–gel synthesis route and characterized through X-ray diffraction, BET specific surface area analysis, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy. The photocatalytic activity of the samples was tested using the degradation of 4-nitrophenol under UV light as model reaction. The ZnO/SnO2 molar ratio was varied in order to study its influence on the photoefficiency of the samples. The ZnO–SnO2 nanocomposites showed higher photoactivity than the pure oxides and in particular the sample with ZnO/SnO2 molar ratio equal to 1/0.05 resulted the best one among the tested powders. The high activity of the mixed samples was attributed to the presence of heterojunctions between the two oxides, which allows an improved charge separation of the photogenerated electron–hole pairs, due to the differences between the energy levels of the conduction and valence bands of ZnO and SnO2. Photovoltage measurements were performed to determine the energy band structure of the ZnO–SnO2 heterojunction.
F-doped TiO2 is synthesized using a modified sol–gel method for visible photocatalytic degradation of MB with a high degradation rate of 91%.
•F-doped TiO2 are synthesized using a modified sol–gel ...method.•The photocatalytic degradation of methylene blue by F-doped TiO2 is investigated.•A high methylene blue degradation rate of 91% is achieved under visible light irradiation.
F-doped TiO2 (F-TiO2) were successfully synthesized using a modified sol–gel method. The morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy, and electrochemical impedance spectra, respectively. The results show that F-TiO2 exhibits an enhanced photocatalytic performance in the degradation of MB with a maximum degradation rate of 91% under visible light irradiation as compared with pure TiO2 (32%). The excellent photocatalytic activity is due to the contribution from the increased visible light absorption, promoted separation of photo-generated electrons and holes as well as enhanced photocatalytic oxidizing species with the doping of F in TiO2.
Transparent ceramics are usually polycrystalline materials, which are wildly used in many optical applications, such as lasers. As of today, the fabrication of transparent ceramic structures is still ...limited to conventional fabrication methods, which do not enable the formation of complex structures. A new approach for 3D printing of micrometer‐size, transparent ceramic structures is presented. By using a solution of metal salts that can undergo a sol–gel process and photopolymerization by two‐photon printing, micrometer‐sized yttrium aluminum garnet (YAG) structures doped with neodymium (Nd) are fabricated. The resulting structures are not only transparent in the visible spectrum but can also emit light at 1064 nm due to the doping with Nd. By using solution‐based precursors, without any particles, the sintering can be performed under air at ambient pressure and at a relatively low temperature, compared to conventional processes for YAG. The crystalline structure is imaged at atomic resolution by ultrahigh‐resolution scanning transmission electron microscopy (STEM), indicating that the doped Nd atoms are located at the yttrium positions. Such miniaturized structures can be used for diverse applications, e.g., optical components in high‐intensity laser systems, which require heat resistance, or as light sources in optical circuits.
Yttrium aluminum garnet (YAG) is a transparent polycrystalline material, which is wildly used as a lasing medium when doped with rare‐earth metal. A new approach for 3D printing micrometer‐size, transparent YAG structures is presented, by using solutions without any particles and two‐photon polymerization printing. By doping the structures with Nd, they can emit light at 1064 nm, making them suitable for microlasers and optical circuits.
The La3+ doped spinel ferrites, Ni0.8Zn0.2LaxFe2−xO4, were prepared by a sol–gel method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating ...sample magnetometer (VSM) and vector network analyzer (VNA). Results show that La3+ can completely substitute into the lattice of Ni0.8Zn0.2Fe2O4 and exist mostly in the form of lamellar structure. Ni0.8Zn0.2LaxFe2−xO4 (X=0–0.1) show the behaviors of the soft magnets and the saturation magnetization (Ms) decreases with the increasing of La3+ content. The electromagnetic property of Ni0.8Zn0.2La0.06Fe1.94O4 is below −10dB at 3.1–5.9GHz and its minimum loss value is −15.43dB at 5.1GHz. Therefore, the introduction of La3+ improves the microwave absorbing properties of Ni0.8Zn0.2Fe2O4.
•Synthesizing Ni0.8Zn0.2LaxFe2−xO4 (X=0–0.1) by a sol–gel method.•Preparing Ni0.8Zn0.2LaxFe2−xO4 with nanometer scale grains.•The doping of La possesses good electromagnetic properties.•Potential applications in magnetic materials and microwave absorbers.
Investigating and understanding in detail the sol-to-gel transition in inorganic and hybrid systems is a very challenging task. The transition is a critical phenomenon that can only be described with ...statistical but not thermodynamic models. Graphic schemes, therefore, cannot easily represent such a complicated process. The sol-to-gel transition has been illustrated with the support of several drawings. Representing complex media, such as the sol and the gel, by a scheme, is however quite tricky. Using oversimplified pictures can mislead the comprehension of the process, which is difficult to describe in general terms, as it depends so much on the synthesis and processing conditions. In this short tutorial, a fault-finding discussion based on the most common pictures drawn to illustrate the sol-to-gel transition has been used for a critical description of the process.
Highlights
Sol–gel transition is a critical phenomenon described by statistical models.
Description of sol–gel transition through pictures should be done with care, to avoid a misinterpretation of the process.
Flexible batteries are essential for wearable electronic devices. To meet practical applications, they need to be mechanically robust and stable. However, strong or multiple bending may sever the ...interfacial contact between electrode and electrolyte, causing capacity fading or even battery failure. Herein we present a new cooling‐recovery concept for flexible batteries, which involves a temperature‐sensitive sol–gel transition behavior of the thermoreversible polymer hydrogel electrolyte. Once a battery has suffered from strong mechanical stresses, a simple cooling process can refresh the electrode–electrolyte interface. The energy‐storage capability can be recovered with a healing efficiency higher than 98 %. It is believed that this study not only offers new valuable insights, but also opens up new perspectives to develop functional wearable devices.
A cooling recovery function for flexible batteries is proposed based on the thermoreversible gelation behavior of the Pluronic hydrogel electrolyte. A simple cooling process can repair the damaged or cracked electrode–electrolyte interface caused by strong mechanical stresses, with a healing efficiency of up to 98 %.
A new type of physically linked double‐network hydrogel is synthesized by a simple, time‐saving, facile, easily controlled, one‐pot method. The resulting agar/polyacrylamide double‐network hydrogels ...exhibit good mechanical properties, excellent recoverability, and a unique free‐shapeable property, which makes them very promising hydrogels for load‐bearing soft tissues.
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