Determination of Reflectance Spectra and Colorimetry of Titanium and Tungsten Oxides Obtained by Microwave-assisted Hydrothermal Synthesis

Sustainability has driven the use of heterogeneous photocatalysis as one of the primary methods for environmental decontamination, reduction, degradation, remediation, or transformation of polluting chemical residues and purification treatment of effluents and wastewater. TiO₂ is the most commonly used semiconductor in heterogeneous photocatalysis. It acquires relevance, as it has favorable properties, such as non-toxicity, stability in a wide range of pH, economic viability, etc., which encourage its application as a semiconductor in photocatalytic processes. However, the photocatalytic capabilities of TiO₂ are only active in 3% of the solar spectrum, which limits its range of use. For this reason, some semiconductor metal oxides were incorporated into TiO₂ to increase its activation range in the UV-visible spectrum. Within this context, WO₃ is a metallic oxide widely used in mixtures with TiO₂, aiming to improve its photocatalytic properties. Thus, this work synthesized TiO₂ and TiO₂ nanostructures mixed with two tungsten precursors (H₂WO₄ and Na₂WO₄.2H₂O) using a microwave-assisted hydrothermal route at 200°C for 120 minutes. The samples obtained were characterized by mL of a 20 ppm solution of methyl orange dye. The results show that it was possible to successfully produce TiO₂ and TiO₂ nanostructures containing tungsten precursors via a microwave-assisted hydrothermal route. This can be attributed to the fact that the energy associated with this temperature was sufficient to convert most of the precursors into crystalline products and little amorphous phase is present.