Sol-gel Method Research Articles

Investigation of the Effects of Different Phases of TiO2 Nanoparticles on PVA Membranes

Introduction: PVA/TiO2 nanocomposite membranes are prepared by solution casting technique where different phases of TiO2 nanoparticles like brookite, brookiterutile and rutile are dispersed in PVA matrix. Sol-gel method was employed to prepare TiO2 nanoparticles, while different phases of TiO2 have been obtained by controlling the calcination temperature. Methods: PVA/TiO2 nanocomposite membranes were characterized by XRD, FTIR, AFM, TEM, UV-visible and PL techniques. XRD results confirmed the presence of different phases of TiO2, exhibiting 3.3 nm, 8.4 nm, and 35.7 nm mean crystalline size. The XRD studies also confirmed that TiO2 nanoparticles became properly dispersed to the PVA matrix, leading to increased PVA crystallinity after doping of different phases of TiO2 nanoparticles. UV-visible analysis revealed an increase in absorption intensity and peak position shifts slightly towards longer wavelengths, which indicates that nanofillers tuned the band gap of PVA. The doping of the TiO2 (brookite) phase in the PVA matrix results in a decreased in PL intensity. Results: This suggests that the PVA/TiO2 (brookite) membrane exhibits a greater degree of photocatalytic activity in comparison to the other two composites. According to the FTIR investigation, the hydroxyl (OH) groups present in PVA interact with the dopants Ti+ ions via intra- and intermolecular hydrogen bonds to produce charge transfer complexes (CTC). The AFM study shows surface roughness details for PVA and PVA/TiO2 composite membranes. The average grain size of TiO2 nanoparticles calculated from TEM images is in good agreement with the grain size calculated by XRD. Conclusion: By adjusting the phase of TiO2 nanoparticles into PVA matrix, composites can be developed that are optimized for a variety of applications such as water purification, UV protection, self-cleaning surfaces, lithium-ion batteries, and optoelectronic devices.

Iron(III) Monoglycerolate as a New Biocompatible Precursor in the Synthesis of Bioactive Nanocomposite Glycerohydrogels.

Nanocomposite glycerohydrogels based on biocompatible elementcontaining glycerolates are of practicular interest for biomedical applications. Using two biocompatible precursors, silicon and iron glycerolates, a new bioactive nanocomposite silicon‒iron glycerolates hydrogel was obtained by sol-gel method. The composition and structural features of the hydrogel were studied using a complex of modern analytical techniques, including TEM, XRD, and AES. On the example of experimental animals hemostatic activity of the hydrogel was studied, as well as primary toxicological studies were carried out. The composition of dispersed phase and dispersion medium of silicon‒iron glycerolates hydrogel was determined. The structural features of hydrogel were revealed and its structure model was proposed. It was shown that silcon-iron glycerolates hydrogel is nontoxic, and exhibits pronounced hemostatic activity. Silicon-iron glycerolates hydrogel is a potential hemostatic agent for topical application in medical and veterinary practice.

Enhancement of luminescence and thermal stability in Eu3+-doped K3Y(BO2)6 with Li+ and Na+ co-doping

Eu3+-doped and Li+/Na+ co-doped K3Y(BO2)6 (KYBO) phosphors were synthesized through a microwave-assisted sol–gel method, and their structural and photoluminescent (PL) characteristics were examined. X-ray diffraction (XRD) and Rietveld refinement confirm effective dopant incorporation and preservation of the crystalline structure. Fourier Transform Infrared (FTIR) spectroscopy indicates the maintenance of the borate structure, confirming the structural integrity of the phosphors upon doping. The addition of Li+ and Na+ co-dopants notably enhances luminescent efficiency and thermal stability, making these phosphors promising candidates for solid-state lighting (SSL) applications. PL analysis reveals strong red emission peaks at 612 nm, attributed to the 5Do → 7F2 transition of Eu3+ ions. The study indicates that electric dipole-quadrupole interactions are the primary mechanism for energy migration, with a critical distance of approximately 22.68 Å. This mechanism contributes to concentration quenching at higher doping levels. High temperature PL measurements indicated an activation energy of 0.1389 eV for thermal quenching in the Li+ co-doped sample. Additionally, the Na+ co-doped sample exhibited an abnormal thermal stability behavior, with an even higher activation energy of 0.2536 eV. This suggests that Na+ co-doping significantly enhances the thermal resilience of the phosphor, making it more suitable for high-power light-emitting applications that operate under extreme conditions. CIE chromaticity diagrams highlight the potential for optimizing Eu3+ doping levels, combined with Li+ and Na+ co-doping, to improve luminescent performance and thermal stability for advanced SSL applications.

Insights into the ternary substitution Na2.96+xK0.04 V2-xNix(PO4)2.98F0.06 with superior rate capability and near-zero strain property

Na3V2(PO4)3 (NVP) is considered the most favorable cathode for sodium-ion batteries due to its solid NASICON skeleton. Nevertheless, poor intrinsic conductivity is insufficient for its further commercialization. In this paper, we present a promising K/Ni/F co-doped and carbon nanotubes (CNTs) encapsulated Na2.96+xK0.04 V2-xNix(PO4)2.98F0.06 (KNF@CNTsx) cathode materials. The synthesis of KNF@CNTsx is achieved using a facile sol-gel method. The replacement of Na+ with K+ broadens the migratory pathway and supports the crystal skeleton, while F− substitution reduces the average grain dimension, thereby increasing the diffusion rate of Na+. Furthermore, the reduction of resistance by Ni2+ doping enables optimization of the transport of electrical charge, while also facilitating the optimization of chemically-defined properties. Concurrently, the optimal quantity of carbon capping and wrapping of CNTs facilitate the formation of efficacious conductive network, which diminishes the size of grains and shortens the pathway for the diffusion of Na+. This network could also serve as a buffer against crystal deformation. In conclusion, the modified KNF@CNTsx samples exhibit notable enhancements in their conductivity, ion diffusion capacity, and structural stability. Among them, the KNF@CNTs0.04 sample exhibits a capacity for reversibility of 93.3 mAh g−1 at 50C, with a remaining capacity of 68.5 mAh g−1 after 4000 successive long charge-discharge cycles. Ex-situ electrochemical XRD demonstrates the V3+/V4+ redox reaction occurs accompanied by the phase transfer reaction, during which Na+ prefers to diffuse along c-axial in the crustal structure. Moreover, volume alteration of this KNF@CNTs0.04 cellular entity is miniscule and reversible during the charge-discharge process, further confirming the stabilized construction and near-zero strain property. The after-cycled XRD/SEM/XPS certify the improved chemical and structural stability of KNF@CNTs0.04, indicating the constructive effects of K/Ni/F ternary substitution.

Visible-light photocatalytic performance of SrTiO3 nanoparticles modified with cobalt.

In this article, an experimental study on the photocatalytic performance of SrTi1-yCoyO3 nanoparticles (with y = 0.0, 0.03, 0.06, and 0.09) synthesized by the Pechini-type sol-gel method is presented. The crystalline structure analysis revealed that all the samples exhibited the cubic perovskite phase of SrTiO3. In particular, the SrTi0.91Co0.09O3 sample was found to consist of rough spherical-like particles with an average size of 26 ± 0.5 nm. Cobalt ions with 2+ and 3+ oxidation states are responsible for modifying the electronic band structure of the semiconductor and a narrowing of optical band gap from 3.1 to 1.08 eV. The resulting Co-doped SrTiO3 nanoparticles exhibited photocatalytic activity under visible light due to their enhanced light absorption, effective charge transport and effective surface chemisorption. In particular, the SrTi0.91Co0.09O3 sample exhibited the highest photocatalytic activity with 91% degradation efficiency of methylene blue dye within 120 min of simulated solar irradiation.

AFe2O4 (A=Cu, Ni, Co, Mg, Ce, Mn) Catalysts for Hydrogen‐Rich Syngas Production from Corn Straw Pyrolysis‐Catalytic Steam Reforming

CuFe2O4, an iron‐based spinel catalyst, along with NiFe2O4, CoFe2O4, MgFe2O4, CeFe2O4, and MnFe2O4 are prepared using the sol–gel method. Different modified transition metals have been investigated to determine the influence on hydrogen production in a fixed‐bed reactor. The results indicated that all the prepared catalysts exhibit a spinel structure. At a reaction temperature of 700 °C, with a water–carbon molar ratio of S/C = 1.5 and a biomass‐to‐catalyst mass ratio of 1:1, the performance ranking of the AFe2O4 spinel catalysts is as follows: CeFe2O4 > CuFe2O4 > MnFe2O4 > NiFe2O4 > CoFe2O4 > MgFe2O4 > no catalyst. CeFe2O4 and CuFe2O4 catalysts demonstrate superior performance, with hydrogen volume fractions of 42.26% and 41.63% respectively. The AFe2O4 catalyst exhibits effective catalytic activity in the production of hydrogen from corn straw using water vapor, with the synergistic effect of A metal and Fe enhancing the catalytic activity of AFe2O4.

Influence of Chelants and Catalyst on Luminescence of CaAl<sub>2</sub>O<sub>4</sub>:Eu<sup>2+</sup> Phosphors for Optical Temperature Sensing Applications

This study synthesized CaAl2O4:Eu2+ blue phosphors using the sol-gel method. The effects of incorporating citric acid, poly (oxyethylene) (PEG), and HCl in the precursor on the luminescent properties of phosphors were investigated. No significant changes were observed in the photoluminescence (PL) spectra of the phosphors when different precursor solutions were used. However, the use of PEG and citric acid led to a noticeable decrease in the PL intensity. Notably, the use of HCl resulted in an increase in PL. In addition, upon heating the phosphors from room temperature to 110 °C, the PL spectrum remained unchanged, whereas the PL intensity decreased linearly with increasing temperature. This indicated the suitability of CaAl2O4:Eu2+ for optical temperature-sensing applications.

Copper oxide/biopolymer nanocomposites: synthesis and applications, a comprehensive review

Copper oxide particles have a significant role in various fields due to their many properties like special shape, size, and high surface area. Due to their rarity and unique characteristics, such as their large surface area, paramagnetic nature, and ease of separation, Copper oxide nanoparticles have received the greatest attention. Chitosan, Guar Gum, Tamarind, Alginate, starch, cellulose, polysaccharide, etc. are examples of natural biopolymers that have proven to be excellent hosts for the creation of CuO nanoparticles. Long-established fabrication techniques for biopolymer-based CuO nanocomposites include co-precipitations, green synthesis, Solvent Casting Method, Alco thermal method, and Sol-Gel methods. Excellent biological characteristics of Copper oxide/biopolymer nanocomposites include their potent antibacterial activity against a variety of diseases as well as bacteria that are resistant to antibiotics. These characteristics have sparked the creation of numerous strategies with direct biological applications, including customized surfaces with antimicrobial effects, wound dressings, and modified textiles. This study aims to provide the very first biopolymer CuO nanoparticles to be reported in the previous ten years as well as its appealing methodology in diverse applications.

Mn-doped ZnO nanopowders prepared by sol–gel and microwave-assisted sol–gel methods and their photocatalytic properties

Although the microwave-assisted sol–gel method is quite frequently used for the preparation of oxide nanostructures, the synergism of the reaction pathways is not fully explained. However, state-of-the-art theoretical and practical results of high novelty can be achieved by continuously evaluating the as-synthesized materials. The present paper presents a comparative study of Mn-doped ZnO nanopowders prepared by both sol–gel and microwave-assisted sol–gel methods. The structural, morphological, and optical properties of the as-obtained powders were established and correlated with their newly proved functionality, namely, the ability to photogenerate distinct reactive oxygen species (·OH or O2−) and to act as photoactive materials in aqueous media. The solar light-induced mineralization of oxalic acid by Mn-doped ZnO materials was clearly observed while similar amounts of generated CO2 were measured for both catalysts. These inexpensive semiconductor materials, which proved to be light-responsive, can be further used for developing water depollution technologies based on solar light energy.

A Spray-Deposited Modified Silica Film on Selective Coatings for Low-Cost Solar Collectors

Solar collectors represent an attractive green technology for water heating, where sunlight is efficiently absorbed by a selective coating and the generated heat is transferred to water. In this work, the improvement and scale-up of an electrodeposited black nickel selective coating with a modified silica (MS) film deposited by spray pyrolysis are reported. The MS material was prepared by the sol–gel method using tetraethyl orthosilicate with the addition of n-propyl triethoxysilane to obtain a porous film with an adequate refractive index and enhanced flexibility. The reflectance of electrodeposited selective coatings was characterized with and without the MS film and compared to a commercially available coating of black paint. The MS film increased the solar absorptance from 89% to 93% while maintaining a much lower thermal emittance than the painted coating. The reflectance of the MS film remained unchanged after prolonged thermal treatment at 200 °C (200 h). The fabrication process was scaled up to 193 cm × 12 cm copper fins, which were incorporated in commercial-size flat-plate solar collectors. Three complete collectors of an area of 1.7 m2 were fabricated and their performance was evaluated under outdoor conditions. The results show that the electrodeposited selective coating with the MS film outperformed both the commercial black paint system and the system without the modified silica film.

Efficient treatment of printing and dyeing reverse osmosis concentrate by a Ti‐NTA/SnO2‐Sb2O3 electrocatalytic membrane

AbstractBACKGROUNDPrinting and dyeing reverse osmosis concentrates (ROC) contain large amounts of salts and organic matter, which is a major environmental issue. The unique composition of such wastewater makes the use of traditional physicochemical techniques challenging.RESULTSIn this paper, titanium dioxide nanotube arrays/SnO2‐Sb2O3 (Ti‐NTA/SnO2‐Sb2O3) electrodes were prepared by anodizing–cathodizing and sol–gel method for the electrocatalytic degradation of printing and dyeing ROC. Organic matter removal under different situations was examined, and the best treatment parameters were identified.CONCLUSIONFollowing treatment, organic matter concentration dropped from 1600 to 50 mg L−1, or even less. The outstanding removal performance of the Ti‐NTA/SnO2‐Sb2O3 electrode was validated by full‐scan ultraviolet spectra, gas chromatography–mass spectrometry and three‐dimensional fluorescence. Evaluation of the dissolved heavy metals and halogenated degradation process byproducts revealed that the electrocatalytic membranes were environmentally safe. These findings highlight the enormous potential of electrocatalytic membranes for the treatment of high‐salt ROC when equipped with a Ti‐NTA/SnO2‐Sb2O3 electrode. © 2024 Society of Chemical Industry (SCI).

Recent research progress on Li29Zr9Nb3O40-based solid electrolytes for lithium batteries

All-solid-state batteries have become a research hotspot because of their high specific capacity and safety. Solid-state electrolytes are the key material of all-solid-state lithium-ion batteries, and their properties directly affect the overall performance of lithium-ion batteries. So far, many inorganic solid electrolytes have been reported, such as NASICON, LISICON, perovskite, and garnet-type solid electrolyte. However, some lithium-rich rock salt-structured electrolytes, such as Li2ZrO3, LiNbO4, and Li6Zr2O7, have been underappreciated in the field of solid-state electrolytes due to their lower ionic conductivity at room temperature. While investigating solid solution formation, Li6Zr[Formula: see text][Formula: see text]Nb[Formula: see text]O[Formula: see text][Formula: see text][Formula: see text], a new phase known as Li[Formula: see text]Zr9Nb3O[Formula: see text] with a rock-salt structure was discovered. After decades, it was not until a team prepared Li[Formula: see text]Zr9Nb3O[Formula: see text] ceramics by sol-gel method, which exhibited high ionic conductivity (10[Formula: see text]–10[Formula: see text]S cm[Formula: see text]) at room temperature, that the substance showed great potential as a solid electrolyte in all-solid-state lithium-ion batteries. In this paper, the crystal structure, lithium-ion transport mechanism, preparation method, and element doping of Li[Formula: see text]Zr9Nb3O[Formula: see text] are described comprehensively based on research progress in recent years. Then, development prospects and challenges of the concrete application of Li[Formula: see text]Zr9Nb3O[Formula: see text]in all-solid-state lithium-ion batteries are also discussed.

An investigation of the electrochemical characteristics of NiO-Co3O4/graphite/PVDF composites for the development of a supercapacitor with ultrahigh stability

Abstract Supercapacitor is a groundbreaking electrical energy storage technology that falls between batteries and dielectric capacitors which has undergone significant progress in recent years. Among the several elements influencing a supercapacitor's capacitance, the choice of electrode materials plays a crucial role. Nanomaterials formed from transition metal oxides with incorporated 3-D graphite are said to possess high capacitance, conductivity, increased area of active site, distinct redox properties, and several valence shells, making them an appropriate material for electrode synthesis. Therefore, in this study, three composites of NiO and Co3O4 are prepared in the ratio 2:8, 3:7 and 4:6 using facile sol-gel method. To the prepared composites, graphite and PVDF are added in equal quantities. The resultant samples are characterized using XRD, SEM, FTIR and UV-Vis spectroscopy. The samples are further integrated on an FTO electrode and subjected to CV, GCD and EIS for electrochemical study. The highest specific capacitance is obtained for NiO and Co3O4 composite in the ratio 3:7 and is equal to 156.66F/g at a sweep rate of 10 mV/s. This material is further used for a two-electrode study to check the feasibility of a symmetric solid-state device, which demonstrated a specific capacitance of 36F/g with 100% capacitive retention.

Enhanced optoelectronic characteristics of La-doped ZnO and its compatibility with Cs-doped MAPbI3 perovskite absorber material

Abstract The present study investigates the structural, electrical and optical characteristics of pristine and lanthanum (La)-doped zinc oxide electron transport layers (ETLs) fabricated by the sol gel method and their compatibility with Cs0.10MA0.90Pb(I0.9Br0.10)3 absorber layer for perovskite solar cells. All the ETLs were deposited under same deposition conditions, with the only difference in La percentage in the precursor solutions, ranging from 0 to 6%. X-ray diffraction (XRD) analysis demonstrated the presence of crystalline ZnO thin films and the absence of any impurity phases after La-doping. The calculated crystallite size, determined using Scherrer’s equation, increased from 11.13 to 21.76 nm after the introduction of dopant. The doping with 4% La led to the decrease in the optical bandgap from 3.32 eV of pristine ZnO to 3.23 eV. SEM analysis revealed better morphology of perovskite/4% La:ZnO specimen, which facilitated the absorbance and reduced the charge carrier recombination. It also exhibited superior resilience towards moisture and humidity which will eventually contribute to the development of more stable and efficient planar perovskite solar cells (PCSs).

Photocurrent in Silic in Silicon/Barium Titanate/Nikel Structures

Photosensitive silicon/barium titanate/nickel structures with undoped barium titanate and doped europium were synthesized using the sol-gel method. The current-voltage characteristics were studied under illumination with a xenon lamp, highlighting a monochromatic line in the range of 400–800 nm and in dark mode. The synthesized structures showed the presence of a photocurrent on the reverse branch of the current-voltage characteristics over the entire studied range of illumination wavelengths. The maximum reverse branch current for a structure with undoped barium titanate was achieved when exposed to radiation with a wavelength of 470 nm and was about 0.6 μA for a bias voltage ranging from 2 to 10 V. Doping barium titanate with europium leads to an increase in the photocurrent by 17–26 %.

Effects of Pt doping on surface properties and quenching of band edge emission in ZnO

Pt doped ZnO thin films were synthesized on soda-lime glass substrates using a cost-effective sol-gel method, followed by spin coating and thermal annealing at various temperatures. Several characterization techniques such as UV–Vis absorption spectroscopy, photoluminescence (PL), field emission scanning electron microscopy (FESEM), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) are exploited to investigate the Pt doping effects on surface and optical properties of ZnO thin films. UV–Vis analysis demonstrated a slight decrease in the optical band gap from 3.3 eV to 3.2 eV with increased annealing, indicating enhanced suitability for optoelectronic applications. FESEM imaging revealed distinct worm-like structures and small Pt metal nanoparticles in unannealed samples, while thermal treatment supported the formation of spherical Pt nanoparticles and improved conductive pathways in the films. The Wagner diagram, coupled with Auger line transitions from XPS, quantified the oxidation states and chemical environments of Zn and Pt, respectively. Notably, the observed changes in the binding energy of the Zn-2p junction and the kinetic energy of the Zn-LMM Auger junction were significantly influenced by the Pt doping and the electronic properties of the substrate. The Wagner diagram provided a comprehensive visual representation of the parameters, facilitating a deeper understanding of electronic interactions and structural dynamics at the atomic level. XPS results confirmed the presence of ZnO, Zn(OH)2, Pt0 and PtO2 phases, indicating stability and constutient's interactions. ToF-SIMS also validated the uniform distribution of Pt nanoparticles within the ZnO thin film, confirming the effectiveness of the sol-gel method. As a result of Pt doping, PL studies revealed a large quenching effect on band edge emission in the UV and visible emission region of ZnO thin film, which is due to Pt acting as a recombination center for photogenerated carriers. Overall, our results highlight the influence of annealing and Pt incorporation on the optical and structural properties of ZnO thin films and highlight their potential applications for photonics and catalysis.

Synergistic effects in Na0.5Bi0.5TiO3-based thin film through stress field regulation for excellent capacitive energy storage

Thin film dielectric capacitors have attracted significant attention under the current trend of integration and portability in electronic devices. In this work, Na0.5Bi0.5(Fe0.03Ti0.97)O3–SrTiO3 (NBFT–STO) thin films are synthesized via sol–gel method onto flexible Pt/Mica and rigid Pt/Ti/SiO2/Si substrates, respectively to obtain NBFT–STO dielectric capacitors under different local stress fields. Synergistic effects between dielectric polarization and breakdown strength (EBD), as well as dielectric polarization and polarization hysteresis are obtained, with the rigid one exhibiting higher EBD and the flexible one possessing high polarization linearity. Excellent capacitive energy storage performance with Wrec of 28.00 J/cm3 and η of 70.44 % are obtained at 20 kHz for the NBFT–STO thin film onto Pt/Mica. These findings provide a new route to modulate polarization behavior of NBT–based thin film through stress field regulation for capacitive energy storage.

Lattice Distortion Creates Enhancements in Photocatalytic and Electrocapacitive Performance of Sol–Gel‐Derived Cu‐Doped NiTiO3

A remarkable 35% enhancement in the photocatalytic and electrocatalytic abilities of an ilmenite nickel titanate (NiTiO3) material is reported. This boost in catalytic performance is achieved by simply creating a static distortion in the rhombohedral unit cell by replacing a small proportion of a small‐size nondegenerate Ni (69 pm) with a large‐size degenerate Cu (73 pm). The materials are synthesized by using a simple sol–gel method. The appropriate doping amount of Cu facilitates the better separation of intrinsic charge carrier pairs by inhibiting their recombination. The photocatalytic and electrochemical activities of durable materials in aqueous MB dye (10 ppm) and KOH (1 molar) electrolyte solutions are found to be directly associated with this improvement in inherent charge carrier transfer characteristics. The enhanced photodissociation of MB dye (42–56%) and specific capacitance (381–450 F g−1) in a KOH (1 molar) electrolyte are in full accord with the investigations carried out using crystallographic and optoelectronic analysis, charging–discharging measurements, and electrochemical impedance (EIS) spectroscopy investigations. Same material with high textural surface areas or controllable particle morphologies might show a far better photo/electrocatalytic performance in a variety of practical applications.

Evaluating fructose content in poultry feed: electrochemical insights

AbstractThe global demand for poultry meat has increased, but consumers have become more picky in their nutritional choices. The fat content of poultry meat has risen since genetic advancement has resulted in higher rates of body weight gain and fat deposition, which are closely linked. The increase in further processing for fast-food poultry items has resulted in larger birds with more body fat. Usually, carbohydrates are used for easy weight gain in poultry. This study focuses on the electrochemical detection of fructose as a feed additive in poultry. The catalyst used was silver–silver oxide–zinc oxide (Ag–AgO–ZnO) and it was prepared by sol–gel method. Further, the surface morphology of the catalyst was analysed using various techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy and transmission electron microscopy (XRD, FTIR and TEM). Cyclic voltammetry was carried out to find out the effectiveness of this catalyst in detecting fructose and our results revealed a sensitivity of 0.3 M with an electrochemical current of 1 mA cm−2, indicating the effectiveness of the chosen electrochemical approach. And further investigation was carried out to monitor effects of various parameters including scan rate, catalyst loading and fructose concentration. This research contributes valuable insights into assessing fructose levels in poultry feed, with potential implications for optimising nutritional formulations and enhancing overall poultry health. The electrochemical method demonstrates promise as a reliable tool for sensitively analysing fructose in feed additives. Precision and accuracy assessments further underscore the reliability of our electrochemical approach in differentiating fructose content within the poultry feed matrix. Graphical Abstract

Construction and Properties of Ultralow Thermal Conductivity and High Strength Zirconia Aerogel Composites by Freeze-Drying.

Zirconia aerogels possess significant applications, including their use catalyst carriers, thermal insulation materials, and thermal barrier coatings. This is due to their ultrahigh temperature resistance, high porosity, and low thermal conductivity. Nonetheless, the inherent challenges associated with ZrO2 aerogels, such as high brittleness, low compressive strength, and inadequate formability, restrict their potential applications. In this paper, with ultralow thermal conductivity and high strength zirconia aerogel composites with inorganic zirconium salt zirconium carbonate as the raw material, acetic acid as the solvent, polyvinylpyrrolidone (PVP) as the viscosity builder to stabilize the structure of the aerogel during the freeze-drying process. Additionally, yttrium nitrate hexahydrate (Y(NO3)3·6H2O) is employed as a phase stabilizer. The sol-gel method, in conjunction with the freeze-drying process, is utilized to fabricate ZrO2 aerogel composites with an optimized microstructure. The findings indicate that optimal process parameters are achieved with a PVP solution concentration of 2.0 wt % and a zirconium carbonate concentration of 20 wt %. The mechanical properties of the resulting composites reach up to 550 kPa, while the thermal insulation performance exhibits a temperature difference of 207 °C/cm and a thermal conductivity of 0.0504 W/(m·K). This advancement addresses the mechanical stability issues commonly associated with traditional ceramic aerogels and widely used elastic insulating materials, thereby enhancing their applicability as thermal insulation and heat preservation materials.