当前期刊: Journal of Sol-Gel Science and Technology Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Sol–gel alumina coating on quartz substrate for environmental protection
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-03
    Mohammed Bouzbib, Andrea Pogonyi, Tamás Kolonits, Ádám Vida, Zoltán Dankházi, Katalin Sinkó

    Abstract Transparent γ-Al2O3 thin film can be utilized as an absorbent or protective layer in environmental protection. The aim of the present research work is to improve the structural and optical properties of γ-Al2O3 thin film. Al2O3 thin films were synthesized by various newly developed routes based on colloidal technique and sol–gel chemistry. Many types of starting materials (Al acetate, nitrate, isopropoxide, boehmite, and Al2O3 powders) and additives (acetic acid, HCl, HNO3, citric acid) were used in the experiments. Suspension and gel-like precursor systems were compared for layer creation. The layers were characterized by their morphology (GIXRD), surface and thickness (SEM), as well as transparency (UV–visible spectroscopy). The best quality of layer (∼90% transmittance, 50–60 nm thickness, perfect covering) has been obtained by sol–gel technique starting from Al nitrate or Al acetate.

    更新日期:2020-01-24
  • Heterojunction catalysts g-C 3 N 4 /-3ZnO-c-Zn 2 Ti 3 O 8 with highly enhanced visible-light-driven photocatalytic activity
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-09-17
    Nelvi Sutanto, Khairul Arifah Saharudin, Srimala Sreekantan, Vignesh Kumaravel, Hazizan Md Akil

    Abstract In this study, pristine ZnO, TiO2, hexagonal-ZnTiO3, and cubic-Zn2Ti3O8 nanoparticles were synthesized by varying the molar ratio of ZnO/TiO2 by sol–gel method assisted with calcinations at 500 °C for 2 h in air. Compared with the pristine phase of zincite (ZnO) and anatase/rutile (TiO2), hybrid nanostructures with 3ZnO:1TiO2 (3ZT) that retain zincite and c-Zn2Ti3O8 demonstrated a higher photocatalytic activity (~82% degradation within 45 min). 3ZT photocatalyst that has been loaded with 10 wt% g-C3N4 has further enhanced visible-light photocatalytic activity performance up to ~99% degradation within 45 min under sunlight illumination. The bandgap energy of 2.5 eV, the formation of a heterojunction of 10g-C3N4/-3ZnO-c-Zn2Ti3O8, crystalline nature of the phases, and high quantity of surface OH− resulted in higher adsorption of organic molecules, causing a substantial improvement in degradation of methylene blue (MB) from ~1.8 to 2.2% per min, which in turn was ~70% better than other reported work.

    更新日期:2020-01-24
  • Sol–gel synthesis of B-TiO 2 (20%)/HZSM-5 composite photocatalyst for azophloxine degradation
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-23
    Lili Yang, Yao Zhao, Yuxuan Liu, Wenjie Zhang

    Abstract Photocatalyst in the supported form is more meaningful in large scale wastewater treatment than using powder material. HZSM-5 zeolite was used to support boron-doped anatase TiO2 in a sol–gel route in this work. The supported B-TiO2(20%)/HZSM-5 composite photocatalyst has strong activity on azophloxine degradation. The crystallite size of anatase TiO2 slightly increased from 6.1 to 8.4 nm when calcination temperature rose from 350 to 450 °C. The bandgap energies were around 3.3 eV for the composites calcined between 350 and 600 °C. The adsorption–desorption isotherm of the composites was the type IV isotherm for mesoporous material. The porous structure in the supported B-TiO2 layer was responsible for the variations of both BET surface area and pore volume in the composite. The maximum photocatalytic activity was obtained on the sample calcined at 450 °C. After 30 min of irradiation, 61.8% of the initial azophloxine molecules were degraded on the material. The first order reaction rate constant was 0.06168 min−1. Photocatalytic degradation efficiency was enhanced with increasing B-TiO2 concentration when the B-TiO2 dosage was below 400 mg/L.

    更新日期:2020-01-24
  • Differentiation of Ni 3 C crystalline phase from hexagonal-close-packed Ni phase in ethylene glycol-mediated sol–gel process and excellent catalytic behavior of Ni/N-doped C nanomaterials toward hydrogenation reduction reaction of 4-nitrophenol
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-08-10
    Jinling Wang, Shengxiang Jiang, Pingyun Li, Hua Ren

    Abstract The ethylene glycol (EG)-mediated sol–gel method was applied to prepare Ni nanoparticles (NPs) where heating treatments of the dried precursors were performed in N2 protecting atmosphere. X-ray diffraction (XRD) analysis was conducted to determine the crystalline phases of the calcinated products. The diffraction peaks of the products being calcinated at 350 °C shifted to lower angles when the initial molar ratio of Ni2+:EG was decreased in the absence of urea, indicating that the crystalline phase of the product calcinated at 350 °C was Ni3C rather than hexagonal-close-packed (hcp) Ni. The Ni3C particles displayed a weak ferromagnetic character at room temperature and the Ni3C phase transformed to face-centered-cubic (fcc) nickel when the heating treatments were performed at 450 °C and higher temperatures. By using urea as an N source, the fcc Ni/N-doped carbon materials could be obtained in the range of 350–600 °C, and the as-prepared fcc Ni/N-doped carbon materials could be used as a catalyst toward the hydrogenation reduction reaction of 4-nitrophenol and an activity parameter of 74.56 s−1 g−1 was obtained. Our results provide a new insight into the differentiation of Ni3C and hcp Ni, and the catalytic behavior of Ni NPs. Nickel/N-doped carbon nanomaterials being calcinated at 350–600 °C by using ethylene glycol mediated sol–gel process have excellent catalytic properties toward hydrogenation reaction of 4-nitrophenol.

    更新日期:2020-01-24
  • Effect of the residual water content in gels on solution combustion synthesis temperature
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-30
    Sh. M. Khaliullin, V. D. Zhuravlev, V. G. Bamburov, A. A. Khort, S. I. Roslyakov, G. V. Trusov, D. O. Moskovskikh

    Abstract The composition of gels and xerogels, as well as their transformation during heating and dehydration, determine the thermochemistry of solution combustion synthesis reactions. An improved descriptive thermodynamic model of combustion processes was formulated on the basis of the investigated formation of complex compounds of metal ions with organic fuel (glycine, citric acid, urea, and PVA) in nitrate solutions. The intensity of SCS reactions was found to depend on the strength of Ni2+–ligand complexes. The effect of heat loss during combustion on the ΔTmax value was analyzed for the model system Ni(NO3)2·nH2O–Fuel–H2O. It was found the heat loss occurs due to the presence of various amounts of structurally-bound water in gels and xerogels before the combustion. The temperature profiles of combustion during the synthesis of NiO with different types of fuel at φ = 1.0.

    更新日期:2020-01-24
  • Mechanical properties and decohesion of sol–gel coatings on metallic and glass substrates
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-03
    David Mercier, Arnaud Nicolay, Abdelhamid Boudiba, Xavier Vanden Eynde, Laure Libralesso, Alain Daniel, Marjorie Olivier

    Abstract The sol–gel coating method is considered to be simple and easy to implement to lead to organic/inorganic hybrid coatings. In addition, the application of thin films by this technique is inexpensive and applicable on large substrates without form restriction. In this context, thin sol–gel coatings based on a mixture of three alkoxysilanes and synthesized in purely aqueous phase with different thicknesses and with the presence or not of ZrO2 nanoparticles, were applied on metallic and glass substrates. After application and curing, the mechanical properties of sol–gel coatings were characterized by Berkovich nanoindentation with continuous stiffness measurement mode (CSM). The effective elastic moduli as well as the hardness values were estimated for each coating along the indentation depth and as a function of the substrate material and sol–gel characteristics. The effect of a annealing at higher temperature was also studied. Then, the failure modes of sol–gel coatings were investigated using both Berkovich nanoindentation and nanoscratch technique with a 5 µm radius spherical diamond tip. Careful microscopic observations of residual imprints and residual grooves both exhibit chipping in case of thick coating especially on glass substrate and no dramatic failure for thin coating applied on both substrates. It is shown in this work that the mechanical properties of the sol–gel and the mechanical stability of coatings on substrates are influenced dramatically by the presence of nanoparticles and the thermal treatment. Finally, interfacial fracture toughness of sol–gel coatings on substrate was estimated using analytical model from the literature and Ashby map based on experimental results was created using performance indices in order to proceed to sol–gel coating selection.

    更新日期:2020-01-24
  • Effect of intermediate layer and electrode materials on dielectric and flexoelectric properties of double-layer BST films with parallel structure
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-18
    Wenbin Dong, Jun Liu, Nan Jiang, Shunling Li, Kai Bi, Ying Luo

    Abstract BST films were prepared on Pt/Ti/SiO2/Si substrates by spin-coating method and double-layer BST films with parallel structure were designed in order to improve their dielectric and flexoelectric properties. The best dielectric constant 409 and dielectric loss 0.0104 of the single-layer BST film are obtained at 800 °C annealing temperature. The dielectric constant of double-layer BST films with parallel structure almost doubled to about 800. The maximum of equivalent piezoelectric constant of the single-layer BST film is 107 pC/N, while the values reach 198 and 251 pC/N, respectively, for BST1/ZrO2/BST2 and BST1/MgO/BST2 parallel structure films. The flexoelectric properties of BST1/MgO/BST2 films are better than those of BST1/ZrO2/BST2 films. When LSCO is applied as the inner electrode, the dielectric properties of the double-layer BST films are better than those applied Au electrode. The curves of transverse flexoelectric signal of the former are smoother than those of the latter.

    更新日期:2020-01-24
  • Structural and optical properties of macroporous Ag@TiO 2 thin films prepared by a facile one-step sol–gel method
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-04
    Shahid Khan, Mahmood ul Haq, Yecheng Ma, Mohammad Nisar, Youduo Li, Rashid Khan, Gaorong Han, Yong Liu

    Abstract A principle of obtaining macroporous Ag@TiO2 thin films by a template-free method in the frame work of sol–gel is developed. The macroporous structure is constructed by photo polymerization induced phase separation (PIPS) method, and the reduction of Ag+ to Ag0 is induced by ultraviolet irradiation at the same time. The achieved macroporous Ag@TiO2 films are well interconnected and crack free with an average pore size in the range 350–440 nm. Increasing Ag concentration results in the enhancement of extinction coefficient and reduction of refractive index, which are found to be consistent with absorbance and transmittance observations. In addition, Ag concentration causes red shift in absorbance which in turn decreases the band gap energy. These results may add important insight into developing high-performance materials for visible light activities.

    更新日期:2020-01-24
  • Multifunctional porous silica nanoparticles for dual responsive drug release
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-09
    Xindang Bo, Qianqian Zhang, Xinli Li, Yanbao Zhao

    Abstract Porous silica nanoparticles (PSNs) were prepared by hydrolysis of tetraethyl orthosilicate and 3-aminopropyltriethoxysilane in emulsion. The PSN carriers with hierarchical pores are suitable for loading drug and controlling release. Chitosan molecules were used to close all drug-loaded pores to reduce the premature release. Hyaluronic acid (HA) modified carbon dots (CDHA) are further used to encapsulate carriers, which endow them enzyme responsiveness. The PSN carriers display pH/enzyme-responsive release and the drug release follows the first-order kinetics model. CDHA can be used not only for fluorescent marker for carriers, but also for qualitative monitoring of the drug release.

    更新日期:2020-01-24
  • Photocatalytic CO 2 reduction over A 2 Ti 6 O 13 (A=Na and K) titanates synthesized by different pH-catalyzed sol–gel
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-09-29
    Luis F. Garay-Rodríguez, Leticia M. Torres-Martínez

    Abstract Na2Ti6O13 (NTO) and K2Ti6O13 (KTO) catalysts were prepared by the sol–gel method by adjusting the pH during hydrolysis. Both the prepared catalysts exhibited a rod-like morphology, demonstrating some microstructural changes such as changes in their rod length, surface area, pore volume, and crystallinity as a result of the pH conditions during synthesis. It is assumed that these changes and the presence of impurities (TiO2) were responsible for the different behaviors observed in the CO2 photocatalytic reduction to formaldehyde and methanol under UV irradiation without any cocatalyst. For example, the NTO sample synthesized without catalyst (neutral media; N-NTO) showed the highest formaldehyde production (93 μmol g−1), which may be due to the presence of TiO2 in both the anatase and rutile phases (up to 10 w%). On the contrary, the neutral synthesized KTO sample (N-KTO), a purer catalyst than NTO (anatase concentration below 5 w%), enhanced methanol production (95 μmol g−1) because of its more favorable physicochemical properties and band position.

    更新日期:2020-01-24
  • Calcium carbonate as silver carrier in composite materials obtained in green seaweed extract with topical applications
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-04
    Cristian Matei, Daniela Berger, Anca Dumbrava, Marius Daniel Radu, Emma Gheorghe

    Abstract Two new Ag–AgCl/CaCO3 composite materials, with different molar ratios Ag:CaCO3, were obtained in a green seaweed (Ulva lactuca) extract by a two steps synthesis. The first step consists in a green, partial reduction of Ag(I) in order to obtain Ag–AgCl crystals, which are deposited in the second step on CaCO3. The composites were characterized by XRD, SEM, EDX, UV–vis, and FTIR spectroscopy. The morphology of composite materials consists in aggregates of calcite nanoparticles, decorated with Ag–AgCl, and the aggregates shape depends on the Ag(I):Ca(II) initial molar ratio. The aggregates are also capped with phytochemicals from green seaweeds, mainly polysaccharides. The composites can be used as a model for the utilization of calcium carbonate as silver carrier in medical applications. The dermatological properties of composites were tested in vivo for healing of burns. An accelerated healing was noticed for the composite with higher silver content. The promising results obtained in vivo recommend the Ag–AgCl/CaCO3 composites for topical applications.

    更新日期:2020-01-24
  • Synthesis of Ag–Carbon–TiO 2 composite tubes and their antibacterial and organic degradation properties
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-30
    Lijun Ji, Xiang Qin, Jingjing Zheng, Shu Zhou, Tong Xu, Guojun Shi

    Abstract Ag–Carbon–TiO2 composite tubes were prepared by using polystyrene/AgNO3 composite fibers as a sacrifice template and a co-pyrolysis process. The Ag–Carbon–TiO2 tubes were characterized by SEM, TEM, X-ray diffraction, Raman spectrum, XPS, and UV–vis spectrum. The results showed that the Ag–Carbon–TiO2 tubes possessed uniform tubular structure with amorphous carbon, graphitic carbon, and Ag nanoparticles (AgNPs) distributing uniformly in TiO2. The Ag–Carbon–TiO2 tubes were confirmed high UV–vis light utilization and photocatalytic degradation efficiency to Rhodamine B due to the carbon doping, the surface plasmon resonance of AgNPs and the tubular structure, and the degradation of Rhodamine B reached 90% in 6 h. Meanwhile, they showed an excellent antibacterial effect on staphylococcus aureus, and the fatality rate of Ag–Carbon–TiO2 tubes to staphylococcus aureus reached 99.9% in 24 h when its concentration was higher than 4 mg/ml. The co-pyrolysis process could repress the AgNPs to grow to be large particles, which could be a key for the excellent antibacterial property. The research showed a promising strategy for preparing Ag–Carbon–TiO2 composite tubes by co-pyrolysis of PS composite electrospinning fibers, indicating their potential application in wastewater treatment and antibacterial materials.

    更新日期:2020-01-24
  • Synthesis of SiO 2 –Al 2 O 3 composite aerogel from fly ash: a low-cost and facile approach
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-13
    Manman Shen, Xuyu Jiang, Mei Zhang, Min Guo

    Abstract A low-cost and simple method was proposed to synthesize SiO2–Al2O3 composite aerogel from fly ash by alkali fusion-acid leaching-ambient pressure drying process just in 3 days for the first time. The effect of the leaching solution’s pH value upon micro-structure and properties of the as-prepared SiO2–Al2O3 composite aerogel was intensively studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 adsorption-desorption, and Fourier transform infrared spectrometry. The as-formed SiO2–Al2O3 aerogel possessed high specific surface area (abbreviated as SSA) of 800 m2/g when the pH value was controlled at 2.7–3.1 (almost up to 900 m2/g at pH = 2.7). Meanwhile, the aerogel exhibited good thermal stability. After calcination at 900 °C for 2 h, the aerogel still remained an amorphous structure with a SSA of 77.88 m2/g. In addition, the related formation mechanism was also discussed.

    更新日期:2020-01-24
  • Controllable preparation of highly uniform γ-alumina microspheres via the sol–gel route for alkoxide in a coaxial microchannel
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-15
    Huilin Yi, Yanchun Wan, Yang Zhang, Yujun Wang, Weiyang Fei, Guangsheng Luo

    Abstract This study describes a novel and facile route for fabricating highly uniform γ-alumina microspheres with controllable size, morphology, and pore structure by integrating the sol–gel route for alkoxide with “temperature/pH-induced gelation” in a coaxial microchannel. Taking advantage of the controllability of the microfluidic devices and Al–O–Al chains formed by the sol–gel route of aluminum alkoxide, the uniformity of the microspheres was assured, and the mechanical strength of the microspheres was greatly improved to 18–27 N/mm2. The effects of the continuous phase composition and two-phase flow rate on the size, morphology, and pore structure of the obtained microspheres were investigated. When triocylamine (TOA) was added to the continuous phase and the two-phase flow rate ratio was larger than 188, the as-prepared microspheres had a smooth surface and good sphericity; otherwise, the microspheres had poor spheriticy and included many ravines on the surface, which can be explained by the mutual influence of long-lasting movements of molecular chains resulted from low gelation speed and inner circulation of the droplets. Under different continuous phase compositions, the average pore diameter, pore volume, and specific surface area ranged from 7 to 12 nm, 0.89 to 1.58 mL/g, and 293.7 to 387.7 m2/g, respectively.

    更新日期:2020-01-23
  • Study on adsorption coupling photodegradation on hierarchical nanostructured g-C 3 N 4 /TiO 2 /activated carbon fiber composites for toluene removal
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-12
    Yuwei Li, Fang Liu, Meng Li, Wei Li, Xuejin Qi, Ming Xue, Yongqiang Wang, Fenglei Han

    Abstract The hierarchical nanostructured g-C3N4/TiO2/activated carbon fiber (ACF) composites are fabricated by simple ultrasonic assisted sol–gel method to removal toluene gas. The results show g-C3N4/TiO2 is evenly loaded onto the ACF surface in the form of a smooth film. The g-C3N4/TiO2/ACF possess strong photocatalytic activity, and its removal efficiency is twice as high as that of TiO2. Compared with TiO2, photoluminescence fluorescence (PL) intensity of g-C3N4/TiO2/ACF decreases nearly 10 times. Interestingly, the significantly enhanced removal efficiency is due to the synergetic effects of adsorption coupling photodegradation and the formation of Ti–O–C bonds between g-C3N4/TiO2 and ACF. The chemical bonding interaction accelerates the separation efficiency of photogenerated charge carriers. The removal efficiency and adsorption amount can be up to 94% and 140.55 mg/g for toluene concentration of 400 mg/m3 and space velocity of 1000 h−1 with 6% g-C3N4/TiO2/ACF. The space-time-yield of g-C3N4/TiO2/ACF reaches 141.06 g h−1 L−1 much higher than that of ACF (73.29 g h−1 L−1) and g-C3N4/TiO2 (64 g h−1 L−1). The possible photodegradation pathway and mechanisms are proposed. Therefore, the g-C3N4/TiO2/ACFs porous composites possess excellent application potential for elimination volatile organic compounds from atmospheric environment. Schematic diagram of the removal of toluene gas from g-C3N4/TiO2/ACF composites.

    更新日期:2020-01-23
  • Facile synthesis of CoFe 2 O 4 magnetic nanomaterial by natural cellulose template and catalytic performance in heterogeneous activation of peroxymonosulfate
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-09-05
    Ping Niu, Chunhui Li, Chunxiao Jia, Dunqing Wang, Shuwu Liu

    Abstract Fibrous cobalt ferrite catalyst was synthesized using the sol–gel method combined with celloulose template. This technology can exactly reproduce the microstructure of cellulose template on nanometer level. The obtained cobalt ferrite was characterized by field emission scanning electron microscope (FESEM), x-ray diffractometry (XRD), fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer. Cobalt ferrite exhibited high efficiency to activate peroxymonosulfate (PMS) for the degradation of Acid Orange 7. The effects of experimental parameters including initial pH values of dye solution, effect of concentrations of PMS and CoFe2O4 on Acid Orange 7 degradation were studied. Furthermore, CoFe2O4 also displayed an extremely high catalytic performance in the degradation of Methyl Orange, Reactive Brilliant Red X-3B, Methylene Blue and Rhodamine B. CoFe2O4 retained high degradation efficiency and high stability even after being reused for five runs. The inherent magnetism of ferrite leads to easy separation of catalyst from the reaction mixtures. Consequently, the catalyst durability is improved remarkably. CoFe2O4 magnetic fiber nanomaterial was synthesized using the sol–gel method combined with celloulose template and exhibited high catalytic activity for AO7 degradation in presence of peroxymonosulfate.

    更新日期:2020-01-23
  • Flame-retardant paper with robust hydrophobicity enabled by perfluorodecane doped SiO 2 nanofibers
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-16
    Yunxi Zhang, Qi Xu, Bofan Jiang, Zhijun Ma

    Abstract Paper plays an important role in various aspects of human life. However, most of the paper materials are vulnerable to both flame and water, which seriously restrict their performance in many applications. Here, we report a new kind of flame-retardant paper with high-temperature-resistant hydrophobicity. This kind of paper was fabricated by vacuum filtration of electrospun fluorinated SiO2 fibers and methyl silicon resin. It is mechanically flexible. Its Young’s modulus is 94 MPa, similar to normal printing paper. The optimized paper demonstrated a water contact angle (WCA) of 151°, which can be maintained as high as 126° even after 30 min of annealing at the temperature of 600 °C. Finally, writing with inorganic ink can be performed on this paper with inhibited ink diffusion. The written paper can maintain its integrity after 5 min of firing by alcohol flame. The flame-retardant and hydrophobic paper here may extend the applications of paper in wide range of fields.

    更新日期:2020-01-23
  • Tri-responsive porous silica carrier with gold nanoparticles for chemophotothermal combination therapy
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-16
    Yunyun Chen, Yanbao Zhao, Lei Sun, Xueyan Zou

    Abstract A multifunctional nanoplatform (pSiO2–Au/HA) combining porous silica (pSiO2) carriers and gold nanoparticles (Au NPs) was synthesized for chemophotothermal synergistic therapy. The pSiO2 carrier has the diameter size of 70 nm and high specific surface area (510.8 m2·g−1). Au NPs as photothermal agents and gatekeepers were linked to pSiO2 carriers by Au–S bonds for redox-responsive drug release and photothermal effect. Hyaluronic acid (HA) molecules were conjugated by the amide bonds on the surface of porous silica (pSiO2) to seal the drug-loaded pores and endow it pH-and enzyme-responsive property. The results demonstrated that pSiO2–Au/HA carriers displayed good pH/redox/enzyme-responsive release behavior and photothermal effect, which may be a good promising targeted delivery systems for chemophotothermal therapy.

    更新日期:2020-01-23
  • Enhanced photocatalytic performance of polyvinylidene fluoride membrane by doped CuFe 2 O 4 nanocrystals for water treatment
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-24
    Enlei Zhang, Lijie Wang, Bengui Zhang, Yingpeng Xie, Guosheng Wang

    Abstract CuFe2O4 nanocrystals with the size about 60 nm were synthesized under hydrothermal conditions, and doped them into polyvinylidene fluoride (PVDF) membranes for enhancing their photocatalytic performance. The morphology, phase, and photoelectric performance of CuFe2O4/PVDF membranes were confirmed by X-ray photoelectron spectroscopic (XPS), scanning transmission microscopy (SEM), and transient photoelectrochemical analysis. As a result, the morphologies of CuFe2O4 nanocrystals could change with the concentration of NaOH solution under hydrothermal conditions. CuFe2O4 nanocrystals showed strong facet-dependent photoelectric and photocatalytic properties. PVDF membrane doped with CuFe2O4 nanocubes showed excellent photocatalytic activity of Congo red degradation (95%), and kept the good self-cleaning performance after five circles. The flux and rejection performance displayed the CuFe2O4 nanocubes/PVDF membrane kept high water flux (40 L/m2 h) and Congo red rejection (99%), and the composite membrane have good potential in water treatment applications. Schematic diagram of the removal of Congo red dye from CuFe2O4/PVDF membrane.

    更新日期:2020-01-23
  • Nitrogen and silver codoped one-dimensional ZnO nanostructure for optoelectronic application
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-09
    Monika Kumari, Virender Singh Kundu, Suresh Kumar, Sonia Siwatch, Nikhil Chauhan

    Abstract In the present work, fabrication and optoelectronic application of nitrogen and silver codoped ZnO nanorod structure have been reported. The synthesized samples were used as photoanodes of dye-sensitized solar cell (DSSC). The as-prepared samples were characterized for structural, optical, morphological, and photovoltaic properties. The XRD spectra showed good crystallinity of all the samples. Optical study revealed the fact that doping has reduced the bandgap of the as-prepared samples. FESEM images confirmed the formation of nanorod structures with a diameter of ~50 nm. The efficiency of DSSC prepared by doped ZnO photoanodes has been increased up to 5.105% as compared with 0.707% for undoped/pure ZnO nanorod-based DSSC. This increase is due to reduced recombination of charge carriers and hence increased value of short-circuit current density caused by nitrogen and silver codoping.

    更新日期:2020-01-23
  • Flame-retardant and water-repellent coating on cotton fabric by titania–boron sol–gel method
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-18
    Aziz Bentis, Aicha Boukhriss, Said Gmouh

    Abstract 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 TiO2–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 TiO2–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 TiO2–boron-based coatings on the mechanical properties of cotton samples, as well as their washing fastness were studied.

    更新日期:2020-01-22
  • Enhancing the red upconversion of water-soluble β-NaErF 4 :Yb nanocrystals through Ca 2+ doping
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-18
    Biao Yu, Xiaoping Zhou, Xiaoshan Tang, Yan Lin, Chunliang Tang

    Abstract With the aim of developing lanthanide fluoride-based nanoparticles (NPs) with enhanced upconversion (UC) luminescence properties, Ca2+-doped water-soluble β-NaErF4:Yb nanocrystals are prepared by a facile solvothermal reaction using ethylene glycol and water as the solvents and comb-like superplasticizer (SP), polyacrylic-co-methyl allyl polyoxyethylene ether copolymer as the capping agent. The SP-capped upconversion nanoparticles (UCNPs) are characterized by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The results show that the capping agent has great influence on the morphology and colloidal solubility of the nanocrystals. The morphological and phase evolution of the nanocrystals is studied. Furthermore, bright red UC luminescence is observed when the sol is irradiated by a 980 nm laser, and the red UC photoluminescence (UCPL) emission is enhanced by eight times upon doping with 50 mol% Ca2+. The decay time and stability of the UCPL are also discussed. With the efficient stable red UC, the Ca2+ doped water-soluble NaErF4:Yb nanocrystals may find use in various optical applications.

    更新日期:2020-01-22
  • Customized hydroxyapatites for bone-tissue engineering and drug delivery applications: a review
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-17
    Gurdyal Singh, Ravinder Pal Singh, Sukhwinder Singh Jolly

    Abstract Hydroxyapatite (HAP, Ca10(PO4)6(OH)2) remains to be the foremost choice in biomedical field right from repair/replacement for the damaged hard tissues to be acting as effective drug delivery agent for tissue healing. Though, HAP is similar in composition with the mineral component of bone, some issues such as lack of mechanical and antimicrobial properties, low degradation, lesser drug loading capability, lower stimuli responsiveness, and targeted deficiency have continuously posed major challenges. However, enactment of various physicochemical, biological, mechanical properties can be improved by articulating particles morphology, size, structure, porosity, synthesis technique, and ionic substitution into HAP structure. Unique structure of HAP permits various anionic and cationic substitutions. Among the available synthesis routes, hydrothermal and microwave-assisted techniques seem to be the most suitable techniques to synthesize HAP with close control over desirable properties. This review primarily focuses on highlighting the customization of desirable properties by controlling particles size, morphology, synthesis parameters, and substitution of mono/multi ions into HAP structure to obtain a product appropriate for bone-tissue engineering and drug delivery applications.

    更新日期:2020-01-22
  • Multivariable analysis of electrodeposited silane based superhydrophobic coatings for corrosion protection of carbon steel
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-17
    Gabriel Batalha Leoni, Denise S. de Freitas, José A. C. Ponciano Gomes, Simone L. D. C. Brasil

    Abstract Superhydrophobic coatings are a field of great interest due to its many applications, including corrosion protection. Such films have been increasingly produced by coupling sol–gel processing with electrodeposition of silane precursors for the sake of its simplicity, controllability, variety of precursors, low toxicity, and low cost. However, despite of the method’s sensitivity to process variables, current literature mostly reports univariate analysis, failing to provide their combined effect and relative importance on response variables. In order to fill this knowledge gap, this paper presents a screening design considering 11 independent variables, followed by a surface response design, to assess the water contact angle (WCA), film thickness, and impedance modulus of silane films electrodeposited onto carbon steel, under several conditions. Here, octyltriethoxysilane (OTES) was selected as one of the sol–gel precursors, since it presents a non-hydrolysable alkyl chain capable of providing low surface energy and consequently water repellence. Results pointed out pH and the ratio between the number of mols of OTES and tetraethoxysilane (TEOS) as key factors for achieving higher WCAs, while pH and the volumetric percentage of water in the deposition solution were the most relevant variables for film thickness. Improved deposition conditions led to WCAs and film thicknesses above 157° and 70 µm, respectively, while monitored impedance modulus at 0.01 Hz in NaCl 3.5 wt% solution were superior to 106 Ohm cm2, even after 48 h of immersion.

    更新日期:2020-01-22
  • Effect of microwave irradiation on the structural, chemical, and hydrophilicity characteristics of ordered mesoporous silica SBA-15
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-17
    Marília R. Oliveira, Monique Deon, Edilson V. Benvenutti, Vinicius A. Barros, Darley C. de Melo, Elton Franceschi, Silvia M. Egues, Juliana F. De Conto

    Abstract Structural, chemical, morphological, and hydrophilic surface characteristics of SBA-15 silica synthesized by hydrothermal method in an autoclave and in a microwave-heated reactor were analyzed in this work. The influence of time and temperature on these characteristics was investigated. Materials were characterized by textural analysis (BET), FTIR, TGA, XRD, goniometer contact angle, SEM, and TEM. It was possible to obtain SBA-15 silicas assisted by microwave heating irradiation with short-time synthesis (0.5–8 h) compared with the hydrothermal classic method (24 h). Materials presented surface area between 650 and 850 m2 g−1. Through the XRD and TEM results, it was observed that mesostructured materials with two-dimensional, long-range, and hexagonal ordered channels are characteristic of SBA-15. This study showed that heating by microwave irradiation during silica synthesis generates materials with a greater amount of silanol groups. It is possible to control the surface properties of SBA-15 during the microwave-assisted synthesis through temperature tuning. Higher temperature provided SBA-15 with higher hydrophilicity.

    更新日期:2020-01-22
  • Obtaining sols, gels and mesoporous nanopowders of hydrothermal nanosilica
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-13
    Vadim Potapov, Roman Fediuk, Denis Gorev

    Abstract Experiments were performed to obtain SiO2 sols, gels, and mesoporous nanopowders based on hydrothermal medium. To achieve this, polycondensation of orthosilicic acid (OSA) at certain pH and temperature, as well as ultrafiltration membrane concentration, sol–gel transition, and cryochemical vacuum sublimation were done. The dynamic light scattering, scanning and tunneling electron microscopy, low-temperature nitrogen adsorption, and others methods determined the physical and chemical characteristics of nanosized SiO2 samples. By choosing the pore size of the ultrafiltration membranes at the sol concentration stage, one can control the ratio of the SiO2 content to the total salt content and provide a zeta potential of nanoparticles sufficient for the stability of the sols. It was shown that by varying the temperature at the polycondensation stage from 20 to 90 °С at pH = 8.5–9.3, it is possible to control the final average diameter of SiO2 particles in the range from 5 to 100 nm, respectively. The specific surface area of particles are 50–500 m2/g, the average diameter of the mesoporous powders in the range of 2–15 nm; the fraction of the area (<4%) and volume (<0.25%) of micropores are low.

    更新日期:2020-01-22
  • Reduced graphene oxide (RGO) induced modification of optical and magnetic properties of M-type nickel doped barium hexaferrite
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-11
    S. Shah, O. P. Pandey, J. Mohammed, A. K. Srivastava, A. Gupta, D. Basandrai

    Abstract In the present study, a heterostructure of Ni doped M-type hexaferrite i.e., BaNi0.2Fe11.8O19 (BNFO) and reduced graphene oxide (RGO) has been prepared to understand its effect on the optical and magnetic properties of BNFO. Here, the preparation of both the components was carried out through sol–gel (followed by heat treatment) and modified Hummer’s method, respectively. The confirmation of phase formation was confirmed with XRD results and spectroscopic techniques (FTIR and Raman) were used to monitor the structural variation occurred as a result of attachment of BNFO and RGO. Further, vibrating sample magnetometry (VSM) and absorbance spectroscopy (UV–visible) were carried out to understand the effect of attachment. VSM study suggested the decrement of saturation magnetization, coercivity, and retentivity as a result of RGO addition in BNFO which might be associated to the soft magnetic characteristics of RGO. While, such synergistic heterojunction induced excellent visible absorption of prepared samples enabling its applicability in optical devices.

    更新日期:2020-01-22
  • Fabrication and photocatalytic behavior of titanium oxide–gold nanoparticles composite ultrathin films prepared using surface sol–gel process
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-11
    Shota Mitsukawa, Tsuyoshi Akiyama, Mikiya Hinoue, Kaho Shima, Takao Takishita, Suguru Higashida, Natsuki Koyama, Kosuke Sugawa, Makoto Ogawa, Hiroshi Sakaguchi, Takeo Oku

    Abstract Ultrathin films consisting of titanium oxide and gold nanoparticles were prepared using a combination of the surface sol–gel process and liquid/liquid interfacial precipitation. The composite films had a titanium oxide/gold nanoparticle layer/titanium oxide film structure, comprising a gold nanoparticle thin-film layer sandwiched within titanium oxide films of nanometer-order thickness. Upon heating the titanium oxide–gold nanoparticle composite films to 450 °C, they underwent a phase change from the amorphous to the anatase phase, which was confirmed via Raman scattering analysis. It was observed that, even after heating, the plasmonic absorption band due to the presence of gold nanoparticles was maintained in the composite films. The photocatalytic degradation efficiencies of methylene blue dye were evaluated in films under 520 nm light irradiation. The results suggested that the sandwich-like structure of this titanium oxide/gold nanoparticle layer/titanium oxide is promising for the visible-light-induced degradation of methylene blue dye.

    更新日期:2020-01-22
  • Influence of metal (M = Cd, In, and Sn) dopants on the properties of spin-coated WO 3 thin films and fabrication of temperature-dependent heterojunction diodes
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-09
    M. Raja, J. Chandrasekaran, M. Balaji, P Kathirvel, R. Marnadu

    Abstract Metal-doped tungsten trioxide (M = Cd, In, and Sn:WO3) thin films were prepared using sol–gel spin-coating and their structural, optical, electrical properties were studied for the fabrication of p–n heterojunction diode. X-ray diffraction (XRD) analysis revealed that Cd, In, and Sn dopants have a strong influence on the lattice parameters and defect factor without making any changes in the structure. Scanning electron microscope (SEM) images reflect that the dopants have a strong impact on the surface morphologies of the WO3 thin film. The UV–visible analysis shows a high optical transmittance (∼82%) and variation in the bandgap was also obtained. The dc electrical conductivity (σdc) indicates that the band conduction mechanism is predominant in the pure and doped M:WO3 thin films. Current density–voltage (J–V) characteristics of WO3/p-Si, Cd:WO3/p-Si, In:WO3/p-Si, and Sn:WO3/p-Si diodes were measured under dark and illumination conditions. In which, the Sn:WO3/p-Si diode exhibits better performance with good ideality factor (n = 2.6) and barrier height (ФB = 0.90) values for under illumination. Most importantly, the J–V–T characteristics of all the fabricated diodes were analyzed with different temperatures (303–423 K).

    更新日期:2020-01-22
  • Assembly of 1T-WSe 2 : Sn nanosheets/graphene by a modified hydrothermal process for water splitting
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-09
    H.-Y. He

    Abstract Transition metal dichalcogenides are one category of potential hydrogen evolution catalyst. Their metallic (1T) structure possesses peculiar optoelectrical properties and so excellent catalytic activity for hydrogen evolution. Here we report a facile modified hydrothermal approach assembling 1T-WSe2 nanosheets and their hybrids with reduced graphene oxide (RGO). The assembled WSe2 nanosheets and the hybrids all showed 1T structures. Moreover, incorporating RGO and doping Sn cation resulted in an efficient interface-induced effect and higher electrical transfer performance and so beneficial properties for hydrogen evolution catalysis. Thus, the RGO/1T-WSe2: Sn nanosheet hybrids showed very high activity and stability for hydrogen evolution catalysis. This work suggests highly efficient and low-cost processes to obtain promising hybrid materials for highly efficient hydrogen evolution catalysis and other photoelectrical applications.

    更新日期:2020-01-22
  • Niobium oxide doped with Tm 3+ and Gd 3+ ions for multimodal imaging in biology
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-09
    Eduardo J. Nassar, Susane B. Moscardini, Séverine Lechevallier, Marc Vereslt, Beata Borak, Lucas A. Rocha

    Abstract The development of new imaging agents able to differentiate tissue, organs, or pathologies more efficiently and presenting good biocompatibility motivates new studies due to its huge importance in the medical field. On the another hand, near-infrared (NIR) fluorescent probes offer advantages such as very high sensitivity, high photon penetration, low-light scattering, and minimal autofluorescence from living tissues, whereas magnetic resonance imaging (MRI) offers better resolution. In this context, this work aimed to obtain particles based on niobium oxide doped with Gd3+ (1, 6, and 10%) and Tm3+ (3%) by the nonhydrolytic sol–gel to be applied as contrast agents as well as nanoprobes for biolabelling. The structure, luminescent properties, and T1/T2 relaxivity behavior were investigated using scanning electron microscopy, X-ray diffraction, fluorimeter, FTIR and Raman spectroscopies, dynamic light scattering, and MRI techniques. The T1 images, no contrast properties can be evidenced which is not surprising for Gd nanoparticles bigger than 10 nm. The T2 image, it can be seen that the signal decreases (increase of T2 contrast properties) as the NPs concentration increases.

    更新日期:2020-01-22
  • Characterization and corrosion protection of nano-titanium dioxide doped BTSE-GPTMS sol–gel coating on cast Al–Si alloy
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-08
    Xuelin Huang, Rui Ke, Yinsheng Dong

    Abstract A hybrid organic–inorganic sol–gel coating was prepared on the surface of cast aluminum–silicon (Al–Si) alloy via dip coating method to improve the anticorrosion ability. In the present work, bis(triethoxysilyl) ethane (BTSE) and 3-glycidoxypropyl-trimethoxysilane (GPTMS) were employed as the precursors to prepare hybrid sol–gel (BG) coating. Nano titanium dioxide (nano-TiO2) was introduced to improve the corrosion resistance of the coating. The microstructures of the BG/nano-TiO2 (BG-T) coating was characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and Fourier-transform infrared (FT-IR) spectroscopy. The results showed that there was a chemical reaction between nano-TiO2 and BG coating and a complete defect-free coating formed on the surface of Al–Si alloy. Moreover, there were a few only minor cracks appeared on the surface of BG-T coating after 15 days immersion in 3.5 wt.% NaCl solution. The corrosion resistant performances of the coatings were evaluated by the electrochemical tests. The results showed that the nano-TiO2 particles elevated the corrosion potential and depressed the corrosion current, thereby improved the corrosion resistance. The long-term immersion tests of BG and BG-T coating further showed that the BG-T coating possesses an excellent long-term stability for corrosion protection.

    更新日期:2020-01-22
  • Biowaste-derived carbon dots/hydroxyapatite nanocomposite as drug delivery vehicle for acetaminophen
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-09-29
    Hui Khee Chung, Viona Wongso, Nonni Soraya Sambudi, Isnaeni

    Abstract In this work, carbon dots/hydroxyapatite (CD-HAP) nanocomposite has been synthesized and used as drug carrier for acetaminophen. Carbon dots are synthesized from a biowaste precursor, which is sugarcane bagasse char using hydrothermal method. The synthesis of carbon dots is studied under four different temperatures of 150, 170, 190, and 210 °C. The fluorescence behaviour of carbon dots is greatest at an optimum temperature of 190 °C. Carbon dots with the best fluorescence properties are merged with the hydroxyapatite. The transmission electron microscopy (TEM) analysis confirms the formation of spherical nanodots with average diameter of 7.5 nm. The field emission scanning electron microscopy (FESEM) analysis confirms the formation of rod-shaped hydroxyapatite with an average diameter of 142 nm. Elemental analysis shows a Ca/P ratio of 1.71, which is close to Ca/P ratio of 1.67 found in natural bone, indicating the biocompatibility of the nanocomposite. Elemental analysis also shows an increase in carbon weight percentage in CD-HAP when compared with blank HAP, proving the formation of carbon dots in the nanocomposite. The pairing of carbon dots and hydroxyapatite improved the fluorescence of composite greatly, as well as the surface area from 41.631 to 78.752 m2/g. The drug loading and release performance is evaluated by loading acetaminophen into the nanocomposite. CD-HAP-40 gives the highest loading capacity of 48.5%. Acetaminophen release is slower in CD-HAP-20, and the release kinetics fits the Higuchi model. This finding shows that the acetaminophen is released via a diffusion mechanism.

    更新日期:2020-01-22
  • Nb 2 O 5 /SiO 2 mesoporous monoliths synthetized by sol–gel process using ammonium niobate oxalate hydrate as porogenic agent
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-08
    Luiz Fernando de Sousa Lima, Cintia Rodrigues Coelho, Gustavo Henrique Magalhães Gomes, Nelcy Della Santina Mohallem

    Abstract Niobium pentoxide/silica mesoporous monoliths were prepared by using silicon alkoxide and a bifunctional reactant, ammonium niobate (V) oxalate hydrate (NbOXA), as niobium pentoxide precursor and porogenic agent. The influence of the thermal treatment on the structural, textural characteristics of the samples was evaluated. The thermal stability of the porous network was also evaluated. The introduction of the NbOXA in the silica sol–gel network promoted an increase in pore size diameter and in the total pore volume. The Nb2O5 nanoparticles were well dispersed inside the mesoporous silica matrix and their presence prevented the pore shrinking of the nanocomposite monolith at high temperatures, maintaining the total pore volume of the nanocomposites higher than those of the silica xerogels. To test the availability of the mesoporous nanocomposites as photocatalysts, they were submitted to UV light for methylene blue photobleaching, used as a model waste compound. Only the nanocomposite treated at 900 °C showed morphology and textural proprieties adequate to be photoactive. Silica/niobium pentoxide composite monoliths with high specific surface area and high pore volume in the range of mesopores, synthesized in one step with high dispersed nanoparticles inside the matrix.

    更新日期:2020-01-22
  • MOF-derived the direct Z-scheme g-C 3 N 4 /TiO 2 with enhanced visible photocatalytic activity
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-09
    Jian Jia, Yanmin Wang, Meiling Xu, Mei-li Qi, Yanling Wu, Gang Zhao

    Abstract In order to produce a photocatalyst with increased visible photocatalytic ability, MIL-125 and melamine were selected as raw materials to prepare Z-scheme g-C3N4/TiO2 heterojunction photocatalyst using a simple calcination method. TEM, HRTEM, XRD, FTIR, EDS, and UV–vis absorption spectra were employed to investigate the prepared specimens. The visible-light catalytic property was examined via the degradation of methylene blue (MB). The recombination and separation activity of electrons and holes (h+/e−) were explored by the transient photocurrent response (TPR) and PL spectra. In contrast with plain TiO2 and g-C3N4, the g-C3N4/TiO2 photocatalyst exhibited increased photocatalytic activities when exposed to visible-light irradiation. With the addition of g-C3N4 at 8 wt%, the Z-scheme g-C3N4/TiO2 heterojunction performed best in the photocatalytic test toward MB dye at a degradation rate of 97.7%. Under visible-light irradiation, the Z-scheme heterojunction between g-C3N4 and TiO2 enables the high-efficient segregation of photogenic electrons and holes (h+/e−), leading to the increased photocatalytic ability. Meanwhile, the large specific surface area of the composite photocatalyst is conducive to the adsorption of the contaminant on the catalyst surface, which has an important effect on the catalytic reaction. The direct Z-scheme g-C3N4/TiO2 was obtained by an in-situ heat treatment process with MIL-125 (Ti) and melamine as raw materials. The g-C3N4/TiO2 photocatalyst with 8 wt% g-C3N4 exhibited the optimal degradation efficiency, which was due to the high separation efficiency of photogenic electrons and holes (h+/e−) of the Z-scheme heterojunction.

    更新日期:2020-01-22
  • Structural, optical, and magnetic properties of low temperature hydrothermal synthesized (Gd, Al)-codoped ZnO nanoparticles
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-21
    Jundong Wang, Weinan Cui, Longshan Zhu, Jin Wang, Qi Wei, Zihang Chen, Meiling Shan, Xi Yuan, Jie Hua

    Abstract Well-dispersed (Gd, Al)-codoped ZnO (Zn0.96–xGdxAl0.04O) nanoparticles (NPs) with different Gd content (x = 0–0.04) were synthesized by low temperature hydrothermal method and their structural, optical, and magnetic properties were investigated. All the as-prepared Zn0.96–xGdxAl0.04O NPs exhibit a hexagonal wurtzite structure with good crystal quality and small particle size (~3 nm). With increasing Gd-doping content from 0 to 0.04, the band gap Eg of Zn0.96–xGdxAl0.04O NPs increases from 3.46 to 3.62 eV owing to the substitution of Gd ions at Zn sites. The presence of additional intrinsic defects Zn-interstitial (Zni) and/or O-vacancy (VO) induced by Gd-doping results in the enhanced PL emission and increased PL lifetime. As compared with Al-doped ZnO, the room temperature ferromagnetic behavior of (Gd, Al)-codoped ZnO system is enhanced remarkably, which is explained based on the O-vacancy mediated exchange interactions between Gd and Al ions.

    更新日期:2020-01-22
  • Correction: Additive-free continuous synthesis of silica and ORMOSIL micro- and nanoparticles applying a microjet reactor
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2020-01-20
    Christina Odenwald, Guido Kickelbick

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.

    更新日期:2020-01-21
  • Fabrication of hybrid CoMoO 4 –NiMoO 4 nanosheets by chitosan hydrogel assisted calcinations method with high electrochemical performance
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-23
    Jing Wang, Yinfeng Cheng, Zhuang Liu, Wenping Cao, Shen Wang, Hongbo Xu

    Abstract Herein, hybrid CoMoO4–NiMoO4 nanosheets (NSs) with mesoporous morphology were assembled using a chitosan hydrogel assisted calcination method. This unique architecture provides numerous channels for rapid diffusion of electrolyte ions, fast electron transfer and high electrochemical activity due to the synergistic effect between the CoMoO4 and NiMoO4. The assembled CoMoO4–NiMoO4 hybrid material can be a very good supercapacitor electrode, due to its high specific capacitance of 1940 F g−1 at the current density of 1 A g−1. Even at a current density as high as 20 A g−1, the CoMoO4–NiMoO4 electrode still delivers a high specific capacitance of 1280 F g−1, indicating its superior rate of specific capacitance 65.98% and excellent cycling stability with capacitance retention 99% after 5000 cycles. Furthermore, the as-prepared CoMoO4–NiMoO4 was employed as anode and activated carbon was used as cathode for solid-state asymmetric supercapacitor. Asymmetric supercapacitors with high power density and energy density (53.33 W h kg−1 at a power density of 800 W kg−1) were realized by improving the potential window with the voltage range from 0 to 1.6 V. These results indicate that the CoMoO4–NiMoO4 electrode shows potential application for high performance, environmentally friendly, and low-cost energy storage device. The hybrid CoMoO4–NiMoO4 nanosheets with mesoporous morphology were assembled using chitosan hydrogel assisted calcinations method. This unique architecture composites exhibit high specific capacitance of 1940 F g−1 at the current density of 1 A g−1. Even at current density as high as 20 A g−1, the CoMoO4–NiMoO4 electrode still delivers a high specific capacitance of 1280 F g−1, indicating its superior rate of specific capacitance 65.98%.

    更新日期:2020-01-17
  • Microencapsulation of cerium and its application in sol–gel coatings for the corrosion protection of aluminum alloy AA2024
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-24
    A. Valero-Gómez, J. Molina, S. Pradas, M. J. López-Tendero, F. Bosch

    Abstract Cerium-containing microcapsules were obtained by means of water/oil (W/O) emulsion technology using tetraethyl orthosilicate (TEOS) as the precursor. Synthesis parameters as water/ethanol molar ratio, surfactant concentration, temperature, synthesis time, were optimized to obtain microcapsules with adequate form and size. Cerium salt is a corrosion inhibitor. Scanning electron microscopy (SEM) was employed to characterize the microcapsules and EDS and energy dispersive X-ray (EDX) microanalysis to assess encapsulation of cerium. The synthesized microcapsules were incorporated in the sol–gel coating that was sprayed on AA2024 aluminum alloy. The morphology of the sol–gel coating and the distribution of the microcapsules were investigated by SEM and EDX and the corrosion resistance of the coated samples was evaluated by electrochemical impedance spectroscopy (EIS) and open circuit potential measurements. Cerium microcapsules can act as Ce nanoreservoirs blocking defects produced in the organic–inorganic hybrid coating by precipitating Ce oxide/hydroxide and nanoloads slowing the diffusion of redox species to the aluminum surface. Higher corrosion resistance was obtained with microencapsulation of cerium than with nonencapsulated cerium. Synthesized microcapsules containing Ce(NO3)3 and incorporated in the sol-gel formulation to provide corrosion protection to AA2024 alloy.

    更新日期:2020-01-17
  • Reducing the thermal hazard of hydrophobic silica aerogels by using dimethyldichlorosilane as modifier
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-08
    Yinfeng Wang, Zhi Li, Lukas Huber, Xiaoxu Wu, Siqi Huang, Yan Zhang, Rui Huang, Qiong Liu

    Reducing organic groups on hydrophobic silica aerogels (SA) is worth exploring for lowering their thermal hazard risk. In this work, we used dimethyldichlorosilane (DMDCS) to modify silica alcogels, investigated the effects of DMDCS concentration and focused on the thermal hazard assessment of the DMDCS modified SA (DSA). It was turned out that the DSA had less −CH3 content in spite of the thermal stability close to the trimethylchlorosilane modified SA (TSA), about 240 °C. The kinetics study suggested the apparent activation energy (Ea) could be divided into two segments, corresponding to the two processes in the pyrolysis. The positive enthalpy and entropy changes indicated that the thermal oxidation of the DSA was an exothermic reaction, which could not occur without external energy supply. The average Ea of the DSA was far larger than that of the TSA and the gross calorific value of the DSA decreased by about 12% compared with that of the TSA. All these results drew a conclusion that the DMDCS modified SA reduced the thermal hazard to some degree, which provided one possible solution to further lower the thermal hazard of hydrophobic SA.

    更新日期:2020-01-16
  • Silver-NPs functionalized hexagonal SBA-15 and lamellar SiO 2 -L81 mesoporous silica, synthesis and structural characterization
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-04
    Issa M. El-Nahhal, Jamil K. Salem, Ahmed Al-agha

    Abstract Silver supported hexagonal SBA-15 and lamellar SiO2-L81 mesoporous silica were prepared via impregnation or co-condensation methods. FTIR, UV-vis., XRD, SEM, and TEM were utilized for determination of their structural properties of the Ag/SiO2 wasnanocomposites. The analysis confirmed that Ag-NPs were successfully loaded into/onto mesoporous silica (hexagonal SBA-15 and lamellar SiO2-L81). The loading of Ag-NPs showed a distortion of mesoporous silica structure via impregnation method, whereas it did not alter the mesoporosity structure, when the co-condensation method was used.

    更新日期:2020-01-16
  • Robust and transparent superoleophobic coatings from one-step spraying of SiO 2 @fluoroPOS
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-26
    Jin Yang, Jiayu Li, Peng Xu, Beibei Chen

    Abstract Transparent superoleophobic surfaces have attracted a great deal of attention due to their broad applications in daily use. But it has been proven that obtaining transparency and superoleophobicity simultaneously is challenging. Here, we report a one-step spraying method to prepare a robust transparent superoleophobic coating using SiO2@fluorinated polysiloxane, which derived through a sol–gel process of fumed SiO2 with tetraethylorthosilicate and perfluorooctyltrichlorosilane. The obtained coating exhibited high transmittance (above 82.3% for wavelength range 400–800 nm) and outstanding superoleophobicity to low surface tension liquids with the contact angles greater than 150° and sliding angles lower than 10°. The influence of SiO2 concentration and spray layer on the transmittance and superoleophobicity of coatings was also investigated. Results showed proper surface roughness and low surface energy are two main factors accounting for superoleophobicity. And to achieve highly transmittance, surface roughness of coating should be less than one-quarter of visible wavelength. More importantly, the superoleophobic coating demonstrated excellent mechanical and chemical stability, which confirmed through a series of experiments such as thermal treating at 300 °C, repelling corrosive liquid droplets, and high-speed sand impact. We envision our findings have a promising development space due to its simple preparation process and outstanding performance.

    更新日期:2020-01-16
  • Aqueous sol–gel processing of precursors and synthesis of aluminum oxynitride powder therefrom
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-28
    Rajendran Senthil Kumar, Sravan Erkulla, Asit Kumar Khanra, Roy Johnson

    Abstract For the first time, aluminum oxynitride (ALON) powders were synthesized using the precursors processed through aqueous sol–gel procedures. Appropriate quantities of aluminum nitride (AlN) powder and aqueous boehmite sol were mixed to obtain molecular stoichiometry of AlON. However, during the course of process, AlN powders reacted with the aqueous boehmite sol and disintegrated into its hydrated compounds. Such reactions altered the molecular stoichiometry between boehmite and AlN which was initially formulated for the eventual formation of AlON. Extensive investigations were carried out to analyse the behavior of AlN during the sol–gel processing. Hydrolysis of AlN in the aqueous sol–gel medium was circumvented by subjecting AlN to a surface modification process. The homogeneously dispersed boehmite sol and AlN mixture was further gelled, dried, and heat treated at temperatures between 1600 and 1850 °C for the formation of AlON powder. AlON phase formation was confirmed through XRD investigations, and its physical and microstructural properties were also evaluated through FESEM and TEM analyses. AlON powder with an average particle size of 490 nm was successfully synthesized in this study. This process is suitable for producing AlON powder in bulk quantities, and it can be used readily for further processes such as shaping and sintering to produce various optical products based on AlON.

    更新日期:2020-01-14
  • Techniques for characterizing the mechanical properties of aerogels
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-14
    Thierry Woignier, Juan Primera, Adil Alaoui, Florence Despetis, Sylvie Calas-Etienne, Annelise Faivre, Laurent Duffours, Claire Levelut, Pascal Etienne

    Abstract In this paper, we present the different characterization techniques used to measure the mechanical properties of silica aerogels. The mechanical behavior of aerogels is generally described in terms of elastic and fragile materials (such as glasses or ceramics) but also in terms of plastic media in compression testing. Because of these very different mechanical behaviors, several types of characterization techniques are proposed in the literature. We first describe the dynamic characterization techniques such as ultrasounds, Brillouin scattering, dynamic mechanical analysis (DMA) to measure the elastic properties: Young’s modulus (E), shear modulus (G), Poisson ratio (υ) but also attenuation and internal friction. Thanks to "static" techniques such as three-point bending, uniaxial compression, compression we also access to the elastic modulus (E) and to the rupture strength (σ). The experimental results show that the values of the elastic and fracture moduli measured are several orders of magnitude lower than those of a material without porosity are. With regard to the brittleness characteristics, Weibull's analysis is used to show the statistical nature of the fracture resistance. We also present the SENB (Single Edge Notched Beam) technique to characterize toughness (KIC) and the stress corrosion mechanisms, which are studied in ambient conditions and temperature by the double cleavage drilled compression experiment (DCDC). In the last part of the paper, we show how, during the isostatic compression test, aerogels behave like plastic materials. The data allow calculating the bulk modulus (K), the amplitude of the plastic deformation and the yield strength (σel), which is the boundary between the elastic and plastic domains. These different techniques allow understanding which parameters influence the overall mechanical behavior of aerogels, such as pore volume, but also pore size, internal connectivity and silanol bounds content. It is shown that the pore size plays a very important role; pores can be considered as flaws in the terms of fracture mechanics.

    更新日期:2020-01-13
  • Density and shrinkage as guiding criteria for the optimization of the thermal conductivity of poly(urethane)-class aerogels
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-26
    Sylwia Członka, Massimo F. Bertino, Jan Kośny, Nitin Shukla

    We investigated the effect of gelation solvent, monomer type, and monomer concentration on the physical properties of freeze-dried poly(urethane)-poly(isocyanurate) (PUR-PIR) aerogels, with particular emphasis on their thermal conductivity. It was found that the gelation solvent considerably affects aerogel morphology and physical properties. Aerogels with the lowest thermal conductivity were obtained using a mixture of tetrahydrofuran (THF) and acetonitrile, in a 50% volume ratio. The influence on thermal conductivity of polyol and isocyanate structure and of their concentration was also investigated. Rigid precursors, phloroglucinol (POL), and an aromatic polyisocyanate based on toluene diisocyanate (Desmodur RC) yielded the lowest thermal conductivity. Our results were compared with recent work reporting on parameters that could be used as predictors of thermal conductivity and other physical properties of organic aerogels. None of these parameters were found to be satisfactory predictors of aerogel properties. For example, no systematic correlation between solvent solubility parameters and aerogel properties was observed. We also examined the role of the K-index. This index, defined as the ratio between porosity and contact angle, was shown recently to be a good predictor of the properties of polyurea aerogels. While the thermal conductivity scaled with the K-index, the scaling was different for each of the isocyanate monomers considered in our experiments. Thermal conductivity, instead, scaled well with the product of density and shrinkage of aerogels, independent of monomer type. The reasons of this dependence on shrinkage and density are discussed, and the use of these parameters to guide experimentation on other systems is discussed. Physical properties such as static and dynamic compression modulus and thermal stability of the most promising formulations were also examined.

    更新日期:2020-01-11
  • Characterization of TiO 2 photoanodes and natural dyes ( Allamanda Blanchetti and Allamanda Cathartica ) extract as sensitizers for dye-sensitized solar cell applications
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-11
    T. Raguram, K. S. Rajni

    In the present work, Dye-Sensitized Solar Cells (DSSC) were fabricated using fabricated TiO2 photoanodes and natural dyes (Allamanda Blanchetti (AB) and Allamanda Cathartica (AC)) as the sensitizers. Initially, TiO2 nanoparticles were synthesized by sol–gel technique and a thin film of TiO2 was formed on the FTO substrate by Doctor Blade technique. Then, they were annealed at 400, 500, and 600 °C to act as the photoanode. X-ray diffraction analysis shows the prepared samples have tetragonal crystal structure with anatase and rutile phase. The average crystallite size was found to be 10–17 nm when the annealing temperature (TA) was increased from 400 to 600 °C. From UV–DRS analysis, the percentage of reflectance was found to starts at 315 nm. The bandgap analysis shows the transitions were indirect allowed and the bandgap value decreases from 3.6 to 2.8 eV when the TA increases from 400 to 600 °C. From the optical absorption spectra, the absorption of dye and dye-sensitized TiO2 was found to be in the visible region. From PL analysis, the emission peak intensity of Ti4+ was increasing with decrease in oxygen (O2−) vacancies with TA increases from 400 to 600 °C was noted. FESEM analysis shows the synthesized particles were spherical and from EDS the presence of Ti and O was confirmed. From FTIR analysis, the functional groups presented in the prepared extracts were confirmed. The Efficiency of DSSC was found to be 1.16 and 0.30% for AB sensitized TiO2 (400 °C) and AC sensitized TiO2 (400 °C) as photoanodes. From Electrochemical Impedance Spectroscopic (EIS) analysis, DSSC with AB + TiO2 shows low charge transfer resistance compared with AC + TiO2.

    更新日期:2020-01-11
  • Controlling the extremely preferred orientation texturing of sol–gel derived ZnO thin films with sol and heat treatment parameters
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-23
    Reza Ebrahimifard, Hossein Abdizadeh, Mohammad Reza Golobostanfard

    Abstract In this article, material and process variables of sol–gel method are considered to investigate the texturing growth model of ZnO thin film in order to achieve ordinary, highly, and extremely preferred ZnO thin films. All the samples were fabricated by deposition of newly developed sol on conventional glass substrate via spin coating method and were further heat treated at various patterns. In sol variable, increasing the molar ratio of triethylamine to Zn increases preferred orientation along c-axis without using special heat treatment pattern. Various heat treatment parameters including drying and calcination are studied. The results demonstrate that drying at 300 °C is essential for achieving highly preferred ZnO thin film. In addition, calcination time, temperature, and repetition leads to more preferred sample to some extent. Furthermore, increasing the drying time at 300 °C causes significant increase of c-axis orientation and extremely preferential growth. In general, selection of an appropriate heat treatment pattern together with an accurate sol composition is necessary to achieve extremely preferred ZnO thin film with less energy conservation without using any special substrate. This is noteworthy that all the ZnO thin films are highly transparent in visible region and their band gap was around 3.3 eV.

    更新日期:2020-01-08
  • Properties of UV-irradiated TiO 2 , ZrO 2 , and TiO 2 -ZrO 2 films as pore-sealing layers on micro-arc-oxidized aluminum alloys
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-04
    Ying Li, Hanxiao Yang, Yuhang He, Qiancheng Zhang, Yonggui Shi, Yuanqing Chen

    In this paper, the UV-assisted sol–gel route was employed to fabricate the TiO2 pore-sealing films on the micro-arc-oxidized (MAO) aluminum alloys (MAO/Al). As compared with the TiO2 film derived from traditional sol–gel method, the UV-irradiated TiO2 film showed a structure with less cracks, resulting in enhanced electrode potential, higher impedance, and lower corrosion current. Further, we investigated and compared the properties of the UV-treated amorphous oxides, including the TiO2, ZrO2, and TiO2-ZrO2 films on MAO/Al. It was found that their corrosion resistances were related to the metallic–oxygen–metallic (M–O–M) lattice in the films. The MAO/Al sealed with UV-irradiated ZrO2 pore-sealing film showed higher corrosion resistance than the samples sealed with UV-irradiated TiO2 film or TiO2-ZrO2 film, which was owing to the fact that a larger amount of M–O–M lattice formed in the UV-ZrO2 film during the UV irradiation.

    更新日期:2020-01-08
  • Effects of sintering temperature on mechanical properties of alumina fiber reinforced alumina matrix composites
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-11-26
    Zhu Chengxin, Cao Feng, Xiang Yang, Peng Zhihang

    Abstract In this study, the continuous alumina fibers reinforced alumina matrix (Al2O3/Al2O3) composites were fabricated through sol–gel method at a sintering temperature range of 900–1400 °C, and their mechanical properties were analyzed separately. To explore the effects of sintering temperature on mechanical properties of composites, the high temperature properties of fibers and matrix were studied in a comprehensive manner. Our results suggested that the composites fabricated at different temperatures exhibited two different fracture features (ductile fracture and brittle fracture). Besides, the 1100 °C fabricated composites possessed the highest flexural strength of nearly 150 MPa. Al2O3 fibers displayed excellent thermal stability, and did not undergo phase transition during the preparation process. However, the grain size of fibers increased dramatically at a sintering temperature of 1200 °C, which led to a significant decrease in the mechanical properties. In the meantime, the surface morphology of fibers became very uneven because of grain coarsening. Due to the phase transition from γ-Al2O3 to α-Al2O3 at 1200 °C, the elastic modulus and microhardness of matrix increased significantly. The higher sintering temperature not only intensified the matrix but also strengthened the interface bonding, thus making the composites prone to brittle fracture. In conclusion, the optimal temperature of composites preparation should be lower than 1200 °C.

    更新日期:2020-01-08
  • In-plane stress development in sol–gel-derived titania and silica thin films on Si(100) substrates
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-30
    Shunsuke Nakanishi, Ryohei Kojima, Hiromitsu Kozuka

    In order to study (i) how the in-plane stress develops in alkoxide-derived oxide gel films on heating and (ii) how the residual stress changes with firing temperature, we prepared titania and silica gel films on Si(100) wafers from alkoxide solutions. The intrinsic stress was previously measured in situ during heating up to 500 °C for the gel films, where the stress was calculated from the radius of curvature of the substrate bending. Because the commercialized apparatus that measures the substrate bending has an upper limitation of temperature at 500 °C, we devised a method for estimating the intrinsic stress over 500 °C in the present work. The gel films were heated from 100 °C up to 900 or 1000 °C successively and cumulatively. Then we estimated the intrinsic stress over 500 °C by monitoring the changes in stress in situ during heating and cooling for the cumulatively fired films. Combining the estimated data over 500 °C with those measured below 500 °C, we found that the intrinsic stress increases and then decreases around to zero with temperature for both titania and silica gel films, which we recognized as a general trend in alkoxide-derived oxide thin films in conjunction with our previous work on yttria stabilized zirconia (YSZ) films. Regarding the residual stress, the titania and silica films exhibited different behaviors. The titania film showed an increase followed by a slight decrease, and finally a significant increase in residual tensile stress with increasing firing temperature. The silica films also exhibited an increase and a decrease in residual tensile stress with increasing firing temperature, but the stress continued to decrease and turned into compressive one at ca 800 °C. The last decrease in residual tensile stress that turned into compressive one resulted from the development of compressive thermal stress during cooling, which is due to the smaller thermal expansion coefficient of silica than silicon. It was thus clarified that the difference in thermal expansion coefficient between the film and the substrate becomes prominent in residual stress when the films are fired at high temperatures like 800 °C. Thus we could successfully obtain a general view on how the residual stress changes with firing temperature as well as on how the in-plane stress develops during heating thanks to the information on the stress development in the sol–gel-derived titania and silica films that was added to the information on the YSZ films.

    更新日期:2020-01-06
  • Synthesis of pyridyl Schiff base functionalized SBA-15 mesoporous silica for the removal of Cu(II) and Pb(II) from aqueous solution
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-14
    Yuanyuan Zhang, Xiang Cao, Jiyuan Sun, Guohao Wu, Jie Wang, Dongen Zhang

    SBA-15 mesoporous materials functionalized with N-propyl-2-pyridylimine and ethylenediaminepropyl-2-pyridylimine denoted as SBA-PA and SBA-NPA were prepared and used as adsorbents for decontamination of aqueous solutions from Cu(II) and Pb(II) ions. Batch tests were carried out and pH value of 5.0 was selected for the adsorption process. The experimental data were well represented by pseudo-second-order kinetic model and Langmuir isotherm model, indicating the adsorption was promoted by chemical process and occurred on monolayer. The theoretical maximum values of sorption capacities of SBA-PA and SBA-NPA for Cu(II) were 35.87 and 48.26 mg/g, and for Pb(II) were 82.05 and 106.62 mg/g, respectively. The adsorption of Cu(II) and Pb(II) was enhanced with the increase of temperature and the thermodynamics parameters were also studied. In addition, the two adsorbents could be easily regenerated over four times without significant loss of adsorption efficiency. Therefore, these nanocomposites prepared here could be promising for heavy metal ions removal in aqueous solution.

    更新日期:2020-01-06
  • Fabrication and characterization of micropatterned La 0.67 Ca 0.33 MnO 3 films via the UV assisted photosensitive solution deposition method
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-14
    Fuxue Yan, Tejing Jiao, Zhichao Jiao, Xiao He, Jiqiang Jia, Yang He, Shuyi Zhangliang, Ping Fu, Lijing Bai, Gaoyang Zhao, Yuanqing Chen

    By using La(NO3)3•6H2O, Ca(NO3)2•4H2O, and Mn(CH3COO)2•4H2O as starting raw materials together with methanol, three kinds of La0.67Ca0.33MnO3 (LCMO) solutions, denoted as LCMO–BzAc, LCMO–AcAc, and LCMO–BPY, respectively, were obtained. The samples were fabricated via the photosensitive solution method with benzoylacetone (BzAc), acetylacetone (AcAc), and 2, 2′-bipyridine (BPY) as chelating reagents. The chelation mechanism of the metal ions was investigated via ultraviolet spectroscopy. The photosensitive compounds were decomposed after UV exposure and their products reduced the solubility of the LCMO gel films in organic solvents. The patterned LCMO thin films were then fabricated by using the self-photosensitive properties of their gel films. Through the mask micromachining process, the LCMO micropatterns prepared by using the LCMO–BzAc solution exhibited the highest quality. Moreover, they also presented good performance when the mask-free method was employed. The magnetic properties of the micropatterned LCMO films were investigated in detail and the results revealed that the micropatterning did not influence their saturation magnetization.

    更新日期:2020-01-06
  • Impact of zinc doping on structural, optical, and electrical properties of CdO films prepared by sol–gel screen printing mechanism
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-12-10
    Renu Kumari, Vipin Kumar

    The simple, economical, eco-friendly sol–gel screen printing mechanism is used to incorporate pure and different zinc- (2, 4, 6, 8%) doped cadmium oxide films on glass substrate at 500 °C calcination temperature. X-ray diffraction (XRD) pattern of prepared films supports the polycrystalline and cubical nature of prepared films. High intensity peak is available at (111) plane for all prepared films. The average crystallite size and strain have been calculated by Williamson–Hall method for all films. The scanning electron microscope (SEM) confirms the impact of zinc on structural morphology of cadmium oxide films. Cd, Zn, O, and absence of any kind of impurities in prepared films has been confirmed by EDAX. It also supports the decrease in atomic percentage of Cd and O with an increase in zinc doping. UV–visible spectroscopy (300–900 nm) of prepared films confirms that the transmittance of films increases up to 60% with 6% doping of zinc and with 8% doping of zinc it decreases. It is also observed that the bandgap first increases up to 2.62 eV on varying doping of zinc from 0 to 6% and then decreases with 8% doping of zinc which clearly shows that the optical properties of cadmium oxide films enhances with doping of zinc. Photoluminescence spectrum of films confirms that there is an enhancement in luminescence property with zinc doping. Fourier transform infrared spectroscopy (FTIR) confirms the presence of Cd–O and O–C–O vibrations in films. Two-probe method has been used for the study of electrical properties of prepared films and it is seen that the electrical resistivity decreases with increase in doping of zinc up to 6% and with 8% doping of zinc it increases.

    更新日期:2020-01-06
  • Influence of sol–gel-derived ZnO:Al coating on luminescent properties of Y 2 O 3 :Eu 3+ phosphor
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-09-07
    Jyung-Dong Lin, Chen-Chang Chen, Chiung-Fang Lin

    This study deposited transparent and conductive Al-doped ZnO (AZO) thin coating on the surface of Y2O3:Eu3+ phosphor particle via a sol–gel method and analyzed the influence of soaking pretreatment, sol concentration, stabilizers, and coating temperature on the microstructure and luminescent properties of AZO-coated Y2O3:Eu3+ phosphors with the aid of SEM, TEM, cathodoluminescence (CL), and photoluminescence (PL) measurements. A water soaking pretreatment was found to effectively improve the coverage and uniformity of the AZO coating, resulting in a continuous and coherent coating. This result is attributed to the presence of adsorbed water and hydroxyl groups on the Y2O3:Eu3+ particle surface after water soaking. Monoethanolamine as a stabilizer agent and higher sol concentration led to a thicker coating on the phosphors. At 800 V or lower, the CL intensity of AZO coated Y2O3:Eu3+ phosphors is significantly greater than that of the uncoated particles and increases with coating thickness. In addition, the PL emission intensity also rises with increasing coating thickness and is even higher than bare phosphors. Further increases in coating thickness beyond the optimum value led to a decrease in PL intensity. This study thus proposes that AZO coatings with sufficient thickness and surface coverage bring about in a higher electron/UV light transport and less surface defects, resulting in an improvement in emission intensity.

    更新日期:2020-01-06
  • State-of-the-art predictive modeling of hydroxyapatite nanocrystallite size: a hybrid density functional theory and artificial neural networks
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-08-20
    Mohammad Shakiba, Gholam Reza Khayati, Maliheh Zeraati

    This study proposes a novel approach for the prediction of crystallite size of prepared hydroxyapatite (HA) by sol–gel technique using density functional theory (DFT) and neural networks (NN). In this regard, various practical variables, viz., aging time, calcination temperature, calcination time, and drying temperature with three phosphor precursors were used as input, and the crystallite size of prepared HA was used as output for NN model. Firstly, exception of phosphor precursor type, all practical variables were directly used as input to NN model. To input the precursor type of phosphor, the difference between energy levels of interacting orbitals of phosphor precursor and calcium nitrate that were calculated by DFT was used. Such approach provides the possibility of conversion of discrete space between phosphor precursors to continuous space, which enables the NN model to predict the crystallite size of HA even for other types of precursors outside the range of investigated by experimental collected data, e.g., Na2HPO4 as case study. To validate the results of NN model, X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) were used for characterization of prepared HA by typically out range phosphor precursor, Na2HPO4. The trained NN model showed an overall mean square error (MSE) of 0.2871 with a linear regression factor of 0.9993, and confirmed the prediction ability of the proposed method for prediction of HA crystallite size effectively.

    更新日期:2020-01-06
  • Superhydrophilicity of photocatalytic ZnO/SnO 2 heterostructure for self-cleaning applications
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-09-20
    Talinungsang, Diliraj Upadhaya, Pankaj Kumar, Debarun Dhar Purkayastha

    Sol–gel spin coating technique was used to deposit thin films of ZnO, SnO2, and ZnO/SnO2 on a borosilicate glass substrate. The films were characterized using XRD, FESEM, EDX, HRTEM, AFM, UV-Vis spectrophotometer, and contact angle meter. X-ray diffraction confirms the presence of both hexagonal wurtzite and tetragonal phase of ZnO and SnO2 respectively in ZnO/SnO2. Wettability studies reveal that ZnO/SnO2 film is superhydrophilic with water contact angle of 3.4°. The photocatalytic performance of the films is evaluated by measuring the degradation of an aqueous solution of methylene blue, methyl orange, and their mixture. The degradation of stearic acid adsorbed on the film’s surface is measured by tracking the water contact angle after UV irradiation as a function of time. The excellent photocatalytic activity of ZnO/SnO2 thin films is attributed to formation of type-II heterostructure between ZnO and SnO2, which inhibits the charge recombination between photogenerated electrons and holes. The ZnO/SnO2 shows good photocatalytic activity after five recycling runs. ZnO/SnO2 thin films being excellent photocatalyst along with its superhydrophilic nature will have potential application in self-cleaning and antifogging.

    更新日期:2020-01-06
  • Morphological and opto-electrical studies of newly decorated nano organo-lead halide-based perovskite photovoltaics
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-09-05
    Abhishek Dhar, Mehul Khimani, Rohit L. Vekariya

    In a world where conventional sources of energy are fast depleting, the quest for alternative energy sources may hold the key for the survival of humanity. In the present work, we have tried to generate energy from perovskite-based solar cells. In order to bring this idea into fruition, a newly developed nano perovskite material n-propyl ammonium lead chloride (C3H7NH3+PbCl3−) was chosen and fabricated via co-precipitation pathway. Here n-propyl amine (n-C3H7NH2), and hydrochloric acid and aqueous solution of Pb(CH3COO)23H2O were used as the starting precursors. Acetic acid was added to the solution at the final stage to maintain the optimum pH of the reaction medium and then the solution was gradually concentrated and cooled down to room temperature. Later, the synthesized material was layered on TiO2 film through spin-coating to generate the targeted device. The device then underwent systematic analysis using XRD, SEM, UV and photo conversion to get a transparent idea regarding its structural, electrical and optical properties. When experimentally applied, this newly developed perovskite-based solar cell has generated appreciable amount of energy conversion efficiency (η) and it is around 6.01%. Thus, it can be concluded that this material is an effective building block of efficient solar cells. This technology can be tried in large scale as a source of nonconventional energy in the upcoming days.

    更新日期:2020-01-06
  • One-step synthesis of methyl eugenol/Schiff base mesoporous silica nanoparticles sustained-release performance with high lure efficiency
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-09-26
    Huayao Chen, Juncai Li, Zhichuan Shen, Hongjun Zhou, Li Hao, Hua Xu, Xinhua Zhou

    Abstract The mesoporous silica nanoparticles (MSN) was modified by salicylaldimine, furfuralimine, and benzaldehyde imine, respectively, denoted as Sal-MSN, Fur-MSN, and Ben-MSN for methyl eugenol (Me) delivery by one-step method. The results confirmed that Me was successfully adsorbed by Schiff base mesoporous silica, which maintained regular hexagonal pore structure. Me is distributed in amorphous state in the pores of the mesoporous silica indicated by differential scanning calorimeter (DSC) curves. Schiff base modification strengthened the interaction between Me and mesoporous silica, leading to its higher sustained-release performance and the disappearance of sudden release in sustained-release performance comparing with Me-MSN before Schiff base modification. Me and Me-MSN were most consistent with the First-order kinetic and logistic equation, respectively. After Schiff base modification, Me-Sal-MSN, Me-Fur-MSN, and Me-Ben-MSN were most consistent with Korsmeryer–Peppas kinetic equation. Therefore, the difference of Me concentration was no longer the main control factor of sustained-release system after Schiff base modification. In the attraction of Bactrocera dorsalis test, the lure efficiency for per unit Me for Me-MSN, Me-Sal-MSN, Me-Fur-MSN, and Me-Ben-MSN equal to 2.83, 3.31, 3.32, 4.24 times of pure Me. After Schiff base modification, the samples showed higher lure efficiency due to their ideal sustained-release performance without sudden release. In short, the lure efficiency of Me was improved by the Schiff base mesoporous silica sustained-release system, in the meanwhile its service life was also prolonged.

    更新日期:2020-01-06
  • Microwave-assisted process for silver/silica sol application onto cotton fabrics
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-10
    Ebru Calhan, Boris Mahltig

    Abstract Silica sols modified with a silver compound are applied onto textile substrates to realize its antibacterial properties. As textile substrates, cotton fabrics are used. The liquid sol recipes are applied by a padding process onto the textiles. Afterwards, a microwave-assisted heating process is applied for drying of the silica sol coating and to form elementary silver nanoparticles. The microwave process is done in a closed autoclave system with process temperatures in the range of 80–140 °C. The process duration is only 5 min short, compared to traditional hydrothermal processes. The coating forming process is strongly determined by the applied process temperature, probably due to boiling and evaporation processes. Lower process temperatures and temperature development used lead to a regular distribution of the silica sol coating on the textile substrates. All prepared coated samples exhibit significant antibacterial properties against the bacteria S. aureus and E. coli. The antibacterial effectiveness increases as a function of silver content and with increasing process temperature of the microwave process. This first experimental set-up can act as first proof-of- concept for effective and fast functionalization of substrates by using microwave technology.

    更新日期:2020-01-06
  • Coprecipitation of Au clusters and alumina sol in supercritical CO 2 —the facile way to stabilize gold nanoparticles within oxide matrix
    J. Sol Gel Sci. Technol. (IF 1.986) Pub Date : 2019-10-09
    N. S. Nesterov, A. S. Shalygin, V. P. Pakharukova, O. N. Martyanov

    Abstract A novel method for the synthesis of catalytically active composites based on gold clusters incorporated into an alumina matrix was proposed. The method combines sol–gel and supercritical fluid technologies. The composites were synthesized by precipitating of gold clusters and alumina sol mixture in the supercritical antisolvent (SAS) carbon dioxide medium. Gold clusters were synthesized in the colloidal solution of alumina sol in situ (one-pot synthesis) via controlled reduction of AuIII using PPh3 as a stabilizer for the first time. It was shown that this method allows us to stabilize gold clusters with sizes less than 2 nm in the alumina matrix with a developed specific surface area (SBET = 441 m2/g) and a narrow pore size distribution. The obtained composite does not contain stabilizer, which may poison the catalyst. The developed approach makes possible to synthesize catalytically active composites with a certain amount of gold cluster and oxide matrix of different nature.

    更新日期:2019-12-27
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
2020新春特辑
限时免费阅读临床医学内容
ACS材料视界
科学报告最新纳米科学与技术研究
清华大学化学系段昊泓
自然科研论文编辑服务
加州大学洛杉矶分校
上海纽约大学William Glover
南开大学化学院周其林
课题组网站
X-MOL
北京大学分子工程苏南研究院
华东师范大学分子机器及功能材料
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug