Synthesis and characterization of binary and ternary nanocomposites based on TiO₂, SiO₂ and ZnO with PVA based template-free gel combustion method

Binary and ternary nanocomposites based on TiO₂, SiO₂ and ZnO were synthesized by PVA-based template-free gel combustion method. The morphology and the particles sizes of the synthesized samples depended on some parameters including the initial concentrations of metal salts and PVA amount in the sol, solvent composition and solution pH. Effects of these parameters were investigated and optimized by using the Taguchi method. In the experimental design, the Taguchi L₂₅ array was used to investigate six factors at five levels. The samples were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) specific surface areas, scanning electron microscopy (SEM). The obtained results showed that the present method can be used to synthesize TiO₂/SiO₂/ZnO ternary nanocomposite with an effective surface area of 0.3 m² · g⁻¹ and ZnO/TiO₂, TiO₂/SiO₂, ZnO/SiO₂ binary nanocomposites with an effective surface area of 234 m² · g⁻¹, 6 m² · g⁻¹ and 0.5 m² · g⁻¹, respectively. The ZnO/TiO₂ nanocomposite which was synthesized under the following experimental conditions: 2.5 wt.% Zn salt, 2.5 wt.% Ti salt, 2.0 wt.% PVA, pH = 1 and ethanol:water ratio 30:70 was selected by the Taguchi method as an optimum sample with the smallest particles (average diameter = 50 nm).