Journal of Sol-Gel Science and Technology最新文献

We present the synthesis of boron carbide aerogels utilizing nano-boron powder and resorcinol–formaldehyde (RF) organic aerogels as precursors. Monolithic aerogels were fabricated from suspensions of boron nanoparticles and RF via an organic sol-gel process, enabling effective distribution of boron in the gel network. The resulting gels underwent supercritical drying, thermal reduction, and subsequent heat treatment to yield boron carbide aerogels with densities ranging from 37 to 55 mg/cm³. By tuning the boron-to-carbon ratio, heat treatment temperature, and dwell time, surface areas up to 53 m²/g were obtained. X-ray diffraction analysis confirmed the formation of the boron carbide phase and detected the presence of residual carbon within the structure.

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Water pollution caused by organic dyes poses a significant environmental challenge, necessitating the development of efficient and sustainable photocatalysts for wastewater treatment. In this present investigation, MnO₂/rGO nanocomposites were prepared using a straightforward one-step microwave-assisted method. The synthesized nanocomposite underwent various analyses, including Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), UV–Vis spectroscopy (UV), as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to assess its physical, structural, and morphological characteristics. The physiochemical results confirmed the successful formation of the MnO₂/rGO nanocomposite, with SEM results revealing a nanocomposite size ranging from 10–20 nm. In assessing the photocatalytic activity of the prepared samples, the degradation of rhodamine-B dye (RhB) was examined under visible light irradiation for 150 min. The MnO₂/rGO nanocomposite exhibited superior photocatalytic activity compared to the pristine sample. Furthermore, a detailed exploration of the photocatalytic degradation mechanism and material stability was conducted. This study provides promising insights into the development of efficient MnO₂/rGO-based photocatalysts for the effective removal of organic pollutants from contaminated water.

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Magnesium alloys, particularly AZ91, are widely used in industries such as aerospace, automotive, and electronics due to their lightweight and high-strength properties. However, their susceptibility to corrosion limits their application in harsh environments. This study presents the development of a novel tri-layer coating composed of nickel (Ni), polyaniline (PANI), and a silane-based sol-gel layer to enhance the corrosion resistance of AZ91 magnesium alloy. The Ni layer provides a robust foundation, while the PANI coating, with its coral-like porous structure, improves adhesion and corrosion resistance. The top silane layer, formed from tetraethylorthosilicate (TEOS) and vinyltriethoxysilane (VTES) by a sol-gel method, offers a smooth, hydrophobic surface that significantly enhances corrosion protection. A range of characterization techniques, including field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR), were applied to analyze the microstructure, surface morphology, and chemical composition of the coatings. The electrochemical performance of the coating was evaluated through electrochemical impedance spectroscopy (EIS) in a 3.5% NaCl solution, revealing a remarkable enhancement in corrosion resistance (86.9 kΩ cm²) compared to bare Mg alloy (0.2 kΩ cm²). Notably, the coating exhibited a corrosion resistance of 12.1 kΩ cm² after 168 h of exposure, still much higher than that of bare Mg, highlighting its long-term protective capacity. The synergistic effects of the Ni, PANI, and silane components were found to be crucial in improving the overall resistance to corrosion. This tri-layer coating presents a promising solution for enhancing the longevity and performance of magnesium alloys in industrial applications.

CeO₂ is one of a key functional material to deposit on different substrates for fabrication of solar cells, fuel cells, and other energy storage applications. The impact of substrate-induced stress on the performance of CeO₂ thin films remains poorly understood. This study investigates the deposition of CeO₂ on three different substrates p-type silicon (p-Si), fluorine-doped tin oxide (n-FTO), and neutral glass followed by Finite Element Analysis (FEA) for mapping residual stress. The charge carrier separation and recombination at the interfaces between CeO₂ and these substrates were analyzed using X-ray diffraction (XRD), ultraviolet-visible (UV), and current-voltage (IV) characteristics. The films were prepared using sol-gel-derived CeO₂ precursors and thermal evaporation, followed by microwave treatment to enhance interfacial charge separation and to suppress recombination. Substrate-dependent microstructural and electronic responses were probed; XRD analysis revealed micro-strain values ranging from 1.6 × 10⁻¹ to 2.3 × 10⁻¹ for CeO₂/p-Si, with larger strain on CeO₂/n-FTO, directly correlated with interfacial defect density and lattice distortion. Additionally, the resistivity of the CeO₂/p-Si junction was 9.95 times lower than that of CeO₂/n-FTO and 7.87 times lower than CeO₂/neutral glass, demonstrating that interfacial charge transport is strongly governed by the underlying substrate. Finite element simulations revealed distinct residual stress profiles 2.67 × 10²MPa for neutral glass, 1.22 × 10²MPa for n-FTO, and 9.49 × 10²MPa for p-Si, correlating with experimental micro strain, conductive, and optical behavior. The results highlight the importance of charge carrier behavior at the substrate interfaces and suggest the potential of CeO₂ based junctions for future energy-related applications.

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Misfit-layered calcium cobaltite Ca_3-xLi_xCo₄O_9+δ (x = 0, 0.1, 0.2 and 0.3) were prepared by the sol-gel route, and the resulting samples were systematically investigated in terms of their phase composition, microstructure, electrical and thermal transport properties. The experimental results revealed that all the samples consisted of the Ca₃Co₄O_9+δ phase and traces of the Ca₃Co₂O_6+δ secondary phase. The chemical composition of the polycrystalline samples was found to be close to the nominal composition, and a characteristic plate-like grain morphology with a high density of grain boundaries was observed. Lithium doping reduced thermal conductivity by 20% (0.81 W/(m.K)) at 300 K for x = 0.3) and yielded the highest thermopower (0.167 mV/K) with a power factor of 0.239 mW/(m⋅K²). An impressive figure of merit value of 0.07 was achieved at room temperature, which was further improved by about 25% compared to the undoped sample.

MXenes, specifically MXene ({{Ti}}_{3}{C}_{2}), are an emerging class of two-dimensional transition metal carbides that have obtained significant attention due to their versatile properties and potential applications through the surface functionalization approach. The surface functionalization of MXenes offers immense possibilities to tailor their properties for a wide range of applications, making them highly flexible materials for next-generation technologies. The current study, using first-principles calculations, has explored the surface decoration of ({{Ti}}_{3}{C}_{2}) MXene with transition magnetic metals (Fe, Mn, and Ni) to influence their optical, electrical, and magnetic properties. Energy band structures and associated density of states result confirmed that peaks of the d-orbital dominate the electronic states in the Fe, Mn, and Ni-({{Ti}}_{3}{C}_{2}) composite. More interestingly, the optical absorption coefficient within ultraviolet and visible infrared regions may be significantly increased by surface decorating with transition magnetic metals Fe, Mn, and Ni-({{Ti}}_{3}{C}_{2}) composite. The remarkably improved optical absorption characteristics over a broad-spectral range may be attributed to the enlargement of the interlamellar space along with more active sites and more electronic mobility. The ferromagnetic simulated results revealed that pristine ({{Ti}}_{3}{C}_{2}) MXene and Ni-({{Ti}}_{3}{C}_{2}) and ({rm{Fe}}-{{Ti}}_{3}{C}_{2}) composites are stable and have magnetic moments of 2.10 µB and 3.04 µB, respectively, and confirmed that Fe, Mn, and ({rm{Ni}}-{{Ti}}_{3}{C}_{2}) composite is a soft ferromagnetic material. The doped MXene demonstrated a good improvement in ferromagnetic performance as compared to the ({{Ti}}_{3}{C}_{2}) MXene. These results suggest that 2D M-depoed Ti₃C₂ MXene (M=Fe, Mn, Ni) materials are superior for solar cell and spintronic device applications.

This study investigates zinc aluminate (ZnAl₂O₄, denoted as Z)-based microwave dielectric ceramics (MDCs) tailored for wireless communication applications, with an emphasis on microstrip patch antenna performance. Titanium doping (ZT) and co-doping with magnesium (ZTM) were employed to enhance essential dielectric parameters, including a near-zero temperature coefficient of resonant frequency (τ_f ≈ 0), moderate relative permittivity (ε_r < 20), and low dielectric loss. The synthesized ZT sample demonstrated a relative permittivity (ε_r) of 13.49 and dielectric loss (tanδ) of 0.39, while the ZTM composite exhibited ε_r = 14.57 and tanδ = 0.158. Antenna prototypes fabricated using these materials showed excellent return losses of –25.96 dB (ZT) and –16.89 dB (ZTM) at an operating frequency of 2.19 GHz, with voltage standing wave ratios (VSWR) below 2, confirming efficient impedance matching. These results position ZnAl₂O₄-based MDCs as promising dielectric candidates for S-band microwave and wireless communication systems.

Sol-gel-derived borate glasses are highly bioactive where they demonstrate rapid production of hydroxycarbonated apatite (HCA), in vitro; making them promising candidates for biomedical applications. Calcination, a critical step in sol-gel processing, significantly influences product properties. This study investigated the effect of calcination temperature on the texture, structure, as well as the reactivity and bioactive properties of sol-gel-derived 40CaO-60B₂O₃ (mol%) samples synthesized from calcium lactate pentahydrate. X-ray diffraction (XRD) confirmed that samples calcined between 400 and 600 °C were amorphous, whereas crystallization occurred when samples were calcined at 700 °C. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy revealed a decrease in BO₄ units with increasing calcination temperature. There was a decrease in specific surface area, attributable to reduced network connectivity and densification, which correlated with a decrease in vapor reactivity, as indicated by dynamic vapor sorption analysis. Bioactivity was confirmed by HCA formation within 7 days in simulated body fluid in all calcined samples, as characterized by ATR-FTIR, XRD, and scanning electron microscopy. In particular, samples calcined at 400 and 500 °C exhibited HCA formation within 1 day. Thermogravimetric analysis revealed that the sample calcined at 400 °C contained the highest amount of organic residues from sol-gel processing. In contrast, the sample calcined at 500 °C combined high bioactivity with optimal thermal decomposition, indicating that this calcination temperature may be suitable for this glass composition. In summary, the successful use of calcium lactate pentahydrate as a low-cost precursor highlights its scalability and potential for producing high-performance sol-gel-derived bioactive borate glasses.

Research on perovskite solar cells (PSCs) has surged due to their promising power conversion efficiency and low fabrication costs. However, the commercial viability of PSCs is hindered by the complex synthesis of the conventional hole transport layer (HTL), such as Spiro-OMeTAD, and the limitations of gold (Au), which is commonly used as a back contact. Specifically, Au tends to diffuse into the perovskite layer over time and react with halide ions, leading to device degradation and reduced long-term stability. In this study, a comprehensive simulation is conducted to evaluate the performance of PSCs with and without HTL, incorporating various metal back contacts. The impact of metal work functions on device performance is systematically investigated. Among the metals analysed, platinum (Pt) emerged as the optimal contact for both configurations due to its high work function and ability to form a stable interface. Focusing on HTL-free designs for structural simplicity, the study explored alternative electron transport layers (ETLs) to replace conventional titanium dioxide (TiO₂), which suffers from poor optoelectronic properties and ultraviolet instability. The performance of various inorganic ETLs, including CdZnS, WS₂, WO₃, ZnO, ZnOS, and ZnSe, is evaluated using SCAPS-1D simulation tool in a typical perovskite solar cell architecture. Among them, ZnOS emerged as the most promising ETL with an open-circuit voltage (V_oc) of 1.22 V, a short-circuit current density (J_sc) of 27.62 mA/cm², a fill factor (FF) of 83.86%, and a power conversion efficiency of 28.39% under optimised conditions. Additionally, an interface defect layer (IDL) of BiI₃ (Bismuth triiodide) is introduced to enhance the long-term device stability. With the IDL, the structure exhibits V_oc of 1.13 V, J_sc of 28.88 mA/cm², FF of 88.48%, and a power conversion efficiency of 28.78%. These findings highlight the potential of Pt-based, HTL-free PSCs for efficient and stable photovoltaic applications.

The development and optimization of high-performance electrode materials are crucial for the progress of next-generation supercapacitors (SCs). Extending our previous study in which pure manganese ferrite (MnFe₂O₄, MF), nickel oxide (NiO, NO) and MnFe₂O₄/NiO (MF/NO₁–₄) nanocomposites (NCs) were prepared by sol–gel auto-combustion technique and extensively studied for their structural, morphological, optical, magnetic and photocatalytic properties; the present study is aimed to further investigation on its electrochemical performance. Detailed electrochemical studies ferroelectric, dielectric, AC conductivity (σ_AC), cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and current–voltage (I–V) analyses were performed without any modification. Ferroelectric characterization showed that the remanent (Pᵣ) and maximum polarization (P_max) for MF and NO were 18.36 μC cm⁻²/4.12 μC cm⁻², respectively, whereas adding more MF significantly enhanced long-range ordering of P_max up to 29.50 μC cm⁻². The dielectric analysis showed the composition-dependent enhancements and the AC conductivity followed Jonscher’s universal power law, indicating a better charge transport mechanism at higher frequency. It was found that the MF/NO-4 achieved a high specific capacitance of 450 F/g, which is 76.12% higher than the pristine material and excellent cyclic stability (74.6% after 2000 cycles) in GCD tests. CV results also confirmed its excellent pseudocapacitive performance (694 F/g). This work uniquely highlights an interfacial-coupling driven correlation between ferroelectric/dielectric behavior and electrochemical performance, which has not been reported previously for MF/NO-4 NCs. The superior electrochemical performance is attributed to the synergistic coupling of MF and NO phases, which promotes redox kinetics, ion diffusion, and structural integrity. This work indicates the potential use of MF/NO-4-based NCs as advanced electrode materials toward high-efficiency energy storage.

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