Abstract:
Ultra-fine composite fibers made from (PVA)/silatrane and (PVA)/tin glycolate were prepared by a combined sol-gel and electrospinning technique. PVA/silatrane composites calcined at 500°C and ≥ 700°C were converted to amorphous silica and cristobalite fibers, respectively. For (PVA)/tin glycolate composite, the acidity of spinning solution plays an important role to the morphology and the size of the obtained fibers. It was found that the ultrafine tin oxide fiber obtained from calcinations at 600°C showed high conductivity value of 1.59x10³ Scm⁻¹ and the high surface area of about 275 m²/g. The effect of calcinations temperature on the phase and the size of both silica fiber and tin oxide fibers were investigated in this study. Hybridizing carbon nanotubes (CNTs) with complex inorganic nanostructures of titanium-silicate (TS-1) provides a new route to designing next-generation photocatalysts. The hybrids were synthesized via a microwave-assisted solvothermal route, using titanium glycolate and silatrane as Ti and Si sources, with the aid of benzyl alcohol as a linking agent. The photocatalytic performance was tested for the degradation of 4-nitrophenol and rhodamine B under UV light as well as visible light. The hybrids showed up to 5 times higher photocatalytic activities compared with the corresponding nano-composite and the individual components, as well as increased selectivity towards total degradation via ring cleavage. For the CNT itself, the hydrophobicity of the CNT surface disfavours the adsorption of hydrophilic particles, thus limiting the quality and performance of the hybrid material. Herein, we demonstrated that using benzyl alcohol as a surfactant enables SiO₂ to interact with the hydrophobic surface of pristine CNTs without the need of covalent functionalisation. The quality of the SiO₂ coating is strongly affected by various reaction conditions, including the order of mixing, the presence of benzyl alcohol, and the reaction temperature. The effect of heat treatment on the crystallization of amorphous SiO₂ to cristobalite is discussed in detail. The key achievement is the well-control of morphology and the structure of the SiO₂ coating and, after removal of the CNTs, of the cristobalite nanotubes, allowing the production of the silica structure with a high surface area-to-mass ratio.
