Journal of Sol-Gel Science and Technology最新文献

The diffusion of specific chain segments, end groups, and incorporated nanofillers across bulk/surface interfaces of coatings contributes to fouling-resistant and even corrosion-inhibition performances. This largely depends on their sizes, the degree of cross-linking within the polymer chains, and how they were chemically grafted. In the present study, an amphiphilic oligomer is first synthesized from by telomerization, before preparing a hybrid polymer blend with a new organosilicon synthesized via the hydrosilylation reaction. This new cross-linked organosilicon/telomer blend with amphiphilic segments, reinforced CaO/SiO₂NPs (SEB1-4), provides improved fouling- and corrosion-resistant performances for low-carbon steel in seawater. Corrosion protection by this polymer coating depends on the blend ratio between the organosilicon gel (OSG) and amphiphilic telomer (AT) precursors. The order of increased corrosion protection is SEB1 (1:1) > SEB2 (1:2) > SEB3 (2:1) > SEB4 (3:1). Compared with an unreinforced coating (i.e., no nanofillers), this reinforced polymer exhibited enhanced antibacterial activity when coated on steel, eliminating the chance of biofilm buildup and surface adherence for a marine bacterium, Pseudomonas aeruginosa. Integrating these nanofillers promoted improved coating adhesion, mechanical strength, and surface protection, while unreinforced coatings exhibited severe disbonding and adhesive/cohesive failures.

Thick and homogeneous coatings with thickness gradients have been developed from aqueous Na-, K- and Li-silicates, also commonly referred to as waterglasses. Thermal treatment of such coatings to 250  °C has allowed to evidence the existence of a critical thickness (CT) below which the coating homogeneity stays intact while intumescence/foaming, crystallization or cracking may be observed above the CT, depending upon the starting composition. Intumescence is observed above CT especially in the case of Na- and K-silicates. Below the CT, water issued from condensation may diffuse outside the film resulting in a reduced thickness of the coating, evidenced from SEM images. Above CT, condensation leads to a non-permeable coating so that water cannot diffuse outside and, thus, creates a foam. Raman spectroscopy depth slice measurements on a flat 20 µm thick coating suggest that the non-permeable coating formed at 150 °C has a reduced amount of water in comparison to the as-deposited coating dried at 55 °C.

Silica aerogel has been widely used in aerospace, energy construction, petrochemical industry. The most significant challenge in the commercialization of aerogels is the high cost. One of the most promising avenues for addressing this issue is the low-cost ambient pressure drying process, which is regarded as a crucial means of reducing the production cost. This study aims to facilitate the industrialization of aerogels prepared via ambient pressure drying. The physicochemical properties of aerogel strongly correlate to the modification methods, such as aging and surface hydrophobicity treatments. Among these methods, solvent exchange plays a key role in synthesizing silica aerogel by ambient pressure drying. In order to facilitate the ambient pressure drying preparation of silica aerogel for industrial application, we designed an efficient automatic solvent exchange device for silica wet gels, and systematically studied the influence of solvent exchange on the physicochemical properties of silica aerogel via ambient pressure drying. After aging and surface hydrophobic modification, the silica wet gels undergo solvent exchange at different temperatures and times. The results show that with the increase of temperature and time, the moisture content of solvent in silica wet gel, as well as the bulk density and thermal conductivity of silica aerogel decrease. Moreover, we studied the effect of solvents with different surface tensions on the physicochemical properties of silica aerogels. The utilization of solvents with low surface tension can result in the production of silica aerogels with a lower bulk density (0.101 g/cm³) and thermal conductivity (0.016 W/m·K), while simultaneously enhancing the specific surface area, pore diameter and pore volume. These findings emphasize the importance of solvent exchange to improve the ability of gel particle network skeleton to withstand irreversible pore collapse via ambient pressure drying.

Graphical Abstract

This study aims to fabricate undoped and 6% Bi-doped MAPbI₂Br perovskite layers using the spin coating method and study their structural, morphological, and photovoltaic properties. The cubic structure of MAPbI₂Br was verified by X-ray diffraction, with relatively large grains being observed in SEM micrographs. Compared to its pristine counterpart, the 6% Bi-doped MAPbI₂Br layer shows an improved refractive index and a smaller bandgap, according to UV-visible spectroscopy. This work presents a dual-layer electron transport layer (ETL) design made of TiO₂ and Al-SnO₂ that is especially suited for PSCs containing MAPbI₂Br as the hole transport layer (HTL). This arrangement marks a major milestone for perovskite solar cells (PSCs) with Bi-MAPbI₂Br as absorber and an inorganic ETL, achieving an open-circuit voltage of 1.07 V and a power conversion efficiency of 10.39%. The conduction band alignment of MAPbI₂Br and Al-SnO₂ promotes effective electron transport, which leads to a reduction of recombination losses and thus enhances the power conversion efficiency of the solar cell.

Graphical Abstract

This investigation employed the sol-gel technique to prepare Co²⁺-Cu²⁺ doped M-type barium-strontium hexagonal ferrite. X-ray diffraction (XRD), along with field emission scanning electron microscopy (FESEM), have been utilized to investigate the crystal structure and morphology of the grains, respectively. An impedance analyzer was utilized to evaluate electrical parameters at room temperature. The formation of an M-type hexagonal crystal *-structure was confirmed by the X-ray diffraction profile, along with minor traces of hematite. In SEM analysis, it was seen that as doping levels are increased, the small size of each grain becomes prominent in the grain clusters, giving rise to a prominent rice-grain shape. The dielectric loss tangent is increased, and the dielectric constant is decreased as doping levels rise. The interplay between grain boundaries and grains has a notable impact on relaxation characteristics across various doping concentrations, leading to the presence of both strong and partial relaxations in low and high-frequency domains. This behavior contributes to the development of either depressed or expanded semicircles influenced by the interactions at grain and grain boundary levels. Analysis of the Cole-Cole plots for electric modulus indicated significant conductivity relaxation. Different relaxation periods were observed in correlation with the conductivity relaxation, and spectra of the electric modulus confirmed the material’s non-Debye behavior.

Graphical Abstract

The pristine anatase titanium dioxide (TiO₂) and transition metal (i.e. Cu and Co) co–doped anatase titanium dioxide nanoparticles (Ti_0.988Cu_0.002Co_0.01O₂) were synthesized using sol–gel auto–combustion technique. Structural, optical and dielectric properties have been studied to understand the effect of dopants across TiO₂ lattice. X–ray diffraction (XRD) and Rietveld refinements confirm the formation of tetragonal structure having I4₁/amd space group, and crystallite size for co–doped TiO₂ nanoparticles falls ~12.68 nm which has been further verified by Raman spectroscopy. UV visible spectroscopy was performed to estimate the band gap energy that gets reduced from ~3.2 eV for TiO₂ to ~1.7 eV for co–doped TiO₂ nanoparticles. Dielectric constant, dielectric loss and ac conductivity for co–doped TiO₂ sample are explained in terms of crystallite size, related grain boundaries and their nature.

Graphical Abstract

In this study, wet chemical methods are employed to synthesize zinc oxide nanocomposites in combination with nickel-iron layered double hydroxides (ZnO@NiFe-LDH). A structural analysis confirmed that ZnO@NiFe-LDH nanocomposites possess tunable surface properties and have been successfully formed. The photocatalytic degradation of methylene blue in aqueous solution was demonstrated under the influence of natural sunlight. A number of photocatalytic parameters were observed, including the initial dye concentration, the pH of the dye solution, anionic effects, and cycling stability. During the deposition of ZnO, 0.75 g of NiFe-LDH was added, resulting in ZnO@NiFe-LDH/3 with the lowest optical band gap of 2.68 eV. A degradation efficiency of 99% was observed for ZnO@NiFe-LDH/3. In the repeatable five degradation cycles of the ZnO@NiFe-LDH nanocomposite, the degradation kinetics followed pseudo-first order, with a slight decrease in degradation efficiency from 99 to 88%. In order to validate the effects of real wastewater environments on the degradation performance of the ZnO@NiFe-LDH nanocomposite, a study was conducted with anionic compounds, such as chloride, sulfate, and nitrate. Results showed that anionic compounds such as chloride, sulfate, and nitrate had a negligible effect on degradation. It is evident from the results of this study that the photocatalyst protocol may have great potential for wastewater treatment.

Graphical Abstract

Left hand side: This work illustrates the synthesis of ZnO@NiFe-LDH composites. Right hand side: The efficient degradation of methylene blue using different catalyst dose under the illumination of natural sunlight.

This study investigates the physicochemical properties and antibacterial activity of hydroxyapatite (HA) nanoparticles synthesized using Basella alba mucilage (BAM) as a natural template and coated with Stephania pierrei (S. pierrei) extract. HA composites were prepared via the sol-gel method with varying BAM concentrations (0–25 wt%) to optimize material properties. S. pierrei tuber and leaf extracts were then incorporated, forming functionalized S. pierrei/BAM-HA materials. Characterization via X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and N₂ adsorption/desorption confirmed the formation of biphasic calcium phosphate structures with enhanced surface area and reduced particle sizes. The 5 wt% BAM composite exhibited the highest surface area (17.59 m²/g) and smallest particle size (6.57 nm). Antibacterial activity was evaluated against Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus aureus, and Bacillus subtilis using the agar well diffusion method. The S. pierrei/BAM-HA composites showed selective antibacterial effects, particularly against Pseudomonas aeruginosa and Bacillus cereus. Notably, 4.0S. pierrei-L/BAM-HA exhibited the strongest activity against Bacillus cereus (MIC and MBC: 4 mg/mL). This research highlights the potential of S. pierrei/BAM-HA composites as antibacterial coatings for implants and bone tissue engineering, while suggesting that further modifications may be needed to enhance antifungal properties.

Graphical Abstract

This research reports on the fabrication and electrochemical characterisation of a new nanocomposite Cu-MOF/MXene for supercapacitor applications. The composite was synthesised through a hydrothermal method involving Ti₃C₂ MXene and a copper-based metal-organic framework (Cu-MOF). X-ray diffraction (XRD) demonstrated formation of the two constituents and high crystallinity, while scanning electron microscopy (SEM) showed dispersal Cu-MOF microcrystals measuring 300–700 nm in size over MXene sheets of size 500-1000 nm. FTIR and photoluminescence (PL) spectroscopy proved strong interfacial interactions, confirming that the composite exhibited an emission peak at 561 nm with a band gap of 2.21 eV. Tauc analysis showed clear optical properties in the visible detection range, and thus Zeta potential showed a surface charge of -18.9 mV which ensures good colloidal stability. Electrochemical impedance spectroscopy (EIS) values demonstrated a charge transfer resistance of 120 Ω and an apparent electron transfer rate of 3.17×10⁻² cm/s. Cyclic voltammetry (CV) confirmed a high specific capacitance of 400 F/g at 5 mV/s and GCD analysis showed a value of 187.5 F/g for 1.0 A/g. The material showed retaining approximately70% of the initial capacitance after 5000 cycles, confirming the superb long-term stability. These results confirm the synergistic development of the MXene/Cu-MOF composite, making it a strong candidate for high-performance energy storage devices.