Microstructural, optical, and photocatalytic properties of TiO2–Bi2O3–GO thin films obtained by sol-gel for applications with sunlight

Abstract

The following study presents the structural, optical, and photocatalytic properties of thin films of titanium dioxide (TiO2) and bismuth trioxide (Bi2O3) in their pure state, as well as mixtures of both oxides in different atomic proportions (with respect to Ti and Bi) and as films modified with a dispersed phase of graphene oxide (GO). The films were sintered at 400 °C, 450 °C, 500 °C and 550 °C. The synthesis of the oxides was carried out by the sol-gel method and the material deposits were synthesized by the dip-coating technique. For mixtures with atomic proportions of 50% and 70% Bi2O3, bismuth titanates were obtained with Bi2(Ti2O7) (cubic) stoichiometry at 550 °C and Bi4Ti3O7 (orthorhombic) stoichiometry at 500 °C, respectively. It was determined that the Bi2(Ti2O7) compound presents the best photocatalytic properties in the degradation of tartrazine in aqueous solution using solar radiation, achieving up to 30% in the photodegradation of the dye. The GO was incorporated in 2% p/p to the precursor solutions of TiO2 and Bi2O3; the resulting materials presented a better photocatalytic activity.

Keywords

• Titanium dioxide
• Bismuth trioxide
• Graphene oxide
• Sol-gel
• Thin film
• Photocatalysis