Sol-gel

About: Sol-gel is a research topic. Over the lifetime, 11843 publications have been published within this topic receiving 262454 citations.

Sol-gel processing of silica. II: The role of the catalyst

Abstract: In the sol-gel synthesis of silica, a silicon-containing raw material, a solvent, water, and a catalyst are utilized. By varying the catalyst, dramatic effects on gelation time, porosity, bulk and apparent density, and volume shrinkage on drying were observed. For example, porosities ranging from two to sixty-eight per cent can be obtained for dried and fired gels. Mechanisms for catalysis have been proposed for the catalysts considered.

Solution-processed zinc oxide field-effect transistors based on self-assembly of colloidal nanorods.

Abstract: Colloidal zinc oxide (ZnO) nanocrystals are attractive candidates for a low-temperature and solution-processible semiconductor for high-performance thin-film field-effect transistors (TFTs). Here we show that by controlling the shape of the nanocrystals from spheres to rods the semiconducting properties of spin-coated ZnO films can be much improved as a result of increasing particle size and self-alignment of the nanorods along the substrate. Postdeposition hydrothermal growth in an aqueous zinc ion solution has been found to further enhance grain size and connectivity and improve device performance. TFT devices made from 65-nm-long and 10-nm-wide nanorods deposited by spin coating have been fabricated at moderate temperatures of 230 °C with mobilities of 0.61 cm2V-1s-1 and on/off ratios of 3 × 105 after postdeposition growth, which is comparable to the characteristics of TFTs fabricated by traditional sputtering methods.

Sol–gel preparation of mesoporous photocatalytic TiO2 films and TiO2/Al2O3 composite membranes for environmental applications

Abstract: This study describes the application of novel chemistry methods for the fabrication of robust nanostructured titanium oxide (TiO2) photocatalysts. Such materials can be applied in the development of efficient photocatalytic systems for the treatment of water. Mesoporous photocatalytic TiO2 films and membranes were synthesized via a simple synthesis method that involves dip-coating of appropriate substrates into an organic/inorganic sol composed of isopropanol, acetic acid, titanium tetraisopropoxide, and polyoxyethylenesorbitan monooleate surfactant (Tween 80) followed by calcination of the coating at 500 8C. Controlled hydrolysis and condensation reactions were achieved through in-taking of water molecules released from the esterification reaction of acetic acid with isopropanol. The subsequent stable incorporation of Ti–O–Ti network onto self-assembled surfactants resulted in TiO2 photocatalysts with enhanced structural and catalytic properties. The properties included high surface area (147 m 2 /g) and porosity (46%), narrow pore size distribution ranging from 2 to 8 nm, homogeneity without cracks and pinholes, active anatase crystal phase, and small crystallite size (9 nm). These TiO2 photocatalysts were highly efficient for the destruction of methylene blue and creatinine in water. High water permeability and sharp polyethylene glycol retention of the prepared photocatalytic TiO2/Al2O3 composite membranes evidenced the good structural properties of TiO2 films. In addition, the multi-coating procedure made it possible to effectively control the physical properties of TiO2 layer such as the coating thickness, amount of TiO2, photocatalytic activity, water permeability and organic retention. # 2005 Elsevier B.V. All rights reserved.