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Acetic anhydride as oxygen donor in the non-hydrolytic sol-gel synthesis of mesoporous TiO2 with high electrochemical lithium storage performances
摘要： An original, halide-free non-hydrolytic sol-gel route to mesoporous anatase TiO2 with hierarchical porosity and high specific surface area is reported. This route is based on the reaction at 200 °C of titanium (IV) isopropoxide with acetic anhydride, in the absence of a catalyst or of a solvent. NMR studies indicated that this method provides an efficient, truly non-hydrolytic and aprotic route to TiO2. Formation of the oxide involves acetoxylation and condensation successive reactions, both with ester elimination. The resulting TiO2 materials were nanocrystalline, even before calcination. Small (≈10 nm) anatase nanocrystals spontaneously aggregated to form mesoporous micron sized particles with high specific surface area (260 m2 g-1 before calcination). Evaluation of the lithium storage performances showed a high reversible specific capacity, particularly for the non-calcined sample with the highest specific surface area favoring pseudo-capacitive storage: 253 mAh g-1 at 0.1C and 218 mAh g-1 at 1C (C = 336 mA g-1). This sample also showed good cyclability (>92% retention after 200 cycles at 336 mA g-1) with a high coulombic efficiency (99.8 %). Synthesis in the presence of a solvent (toluene or squalane) offers the possibility to tune the morphology and texture of the TiO2 nanomaterials.
关键词： anatase,mesoporous,acetic anhydride route,non-hydrolytic sol-gel,Li-ion batteries
更新于2025-09-23 15:23:52
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Influence of Synthesis Conditions on Microstructure and NO2 Sensing Properties of WO3 Porous Films Synthesized by Non-Hydrolytic Sol–Gel Method
摘要： Nanostructured tungsten trioxide porous films were prepared by a non-hydrolytic sol–gel method following the inorganic route in which ethanol and PEG were used as the oxygen-donor and structure-directing reagent, respectively. The effects of aging time of the precursor solution, PEG content, and calcination temperature on the structure, morphology, and NO2 sensing properties of WO3 films were systematically investigated by using the techniques of X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and gas sensing measurements. The results demonstrated that a series of WO3 films with different microstructures could be obtained by manipulating the synthesis parameters. Furthermore, a suitable synthesis condition of WO3 films for NO2 sensing application was determined.
关键词： NO2,non-hydrolytic sol–gel,WO3,gas sensing,porous films
更新于2025-09-23 15:23:52
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The Sol-Gel Method: Pathway to Ultrapure and Homogeneous Mixed Metal Oxide Nanoparticles
摘要： This article includes an overview of current research on metal oxides and mixed (heterobi-) metal oxides prepared by sol-gel method using variety of precursors which created interest among scientists and technologists due to their structure, reactivity as well as application in almost every field of science. Sol-gel method is a soft-chemistry method requires mild reaction conditions, less equipments as well as produces materials with ultra purity and therefore, widely used as compared to other methods. Authors have explained hydrolytic sol-gel method with examples in the first section and compared the method with conventional solid state method. This section is further divided into subsections explaining the process using metal salts such as chlorides, nitrates, etc. and metal-organic compounds as precursor with chelating ligands, polyols, etc. The importance of using heterometallic alkoxides as precursor rather than using two different metal precursors is also explained and finally the new advancement in sol-gel method.
关键词： Nanoparticles,Hydrolytic sol-gel,Sol-gel,Metal oxide,Mixed metal oxide
更新于2025-09-23 15:22:29
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A New Dealcoholization Method in the Synthesis of Vinyl Methyl Phenyl Silicone Resins for LED Encapsulation
摘要： The oligosiloxane resins were synthesized through hydrolytic sol-gel reaction and remained many hydroxyl groups, which did great harm to the curing process and resulted in poor performance of the cured products. In previous works, epoxy-modified silicone resins were synthesized by dealcoholization, a reaction between 3-glycidoxypropylmethyldimethoxysilane and terminal hydroxyl groups in phenyl silicone resins. Although this method eliminated the hydroxyl groups, it caused a large loss of vinyl groups inevitably and a poor stability of cured products. In this study, methyltrimethoxysilane (MTMS) was used to eliminate hydroxyl groups containing in vinyl methyl phenyl silicone resins, which were synthesized through hydrolytic sol-gel reaction. Most of residual hydroxyl groups were deleted effectively and the great loss of vinyl groups were avoided in the dealcoholization reaction. Then, the methyl phenyl silicone materials were fabricated by hydrosilylation reaction between the synthesized vinyl methyl phenyl silicone resins and hydrogen-containing ones. The cured silicone materials showed excellent optical performance (~ 89.1% at 450 nm) and good adhesion performance. In addition, due to less vinyl loss in the vinyl methyl phenyl silicone resins, the cured methyl phenyl silicone materials exhibited higher cross-linking density, better thermal resistance (5% mass loss at 435 °C) and better mechanical properties (50 shore D) compared with the epoxy-modified phenyl silicone materials. The lumen depreciation (working 168 h at 50 mA) and reflow soldering tests further demonstrated the methyl phenyl silicone materials possessed good thermal stability. These results indicated that the methyl phenyl silicone materials could be used as a LED encapsulant with a good performance.
关键词： LED packaging,Methyltrimethoxysilane,Non-hydrolytic sol-gel,Hydrolytic sol-gel,Vinyl methyl phenyl silicone resin
更新于2025-09-19 17:13:59
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Influence of Calcination Temperature on the Performance of TiO<sub>2</sub> Films in Dye-Sensitized Solar Cells
摘要： In this work, the effects of calcination temperature on the photovoltaic performance of TiO2 films prepared with non-hydrolytic sol-gel method were reported. The optimal photovoltaic performance of DSCs was obtained by annealing TiO2 film at 550 °C. The short-circuit current (Jsc), open-circuit voltage, fill factor (FF) and energy conversion efficiency were 15.68 mA·cm-2, 0.71 V, 0.62 and 6.83%, respectively.
关键词： dye-sensitized solar cell,photoanode film,performance,calcination temperature,non-hydrolytic sol-gel titanium dioxide
更新于2025-09-16 10:30:52