Propriedades estruturais, morfológicas e fotocatalíticas do β-SnWO4 sintetizado via moagem mecânica

Abstract

The dissertation presents a new route for obtaining tin tungstate in beta phase (β-SnWO4) by high-energy mechanical milling (High Energy ball milling - HEBM), a green and low-cost synthesis technique that uses grinding balls in a mill with high rotation. The synthesis precursors are in solid state, and in this work they refer to 2.73x10−3 mol of metallic tin (Sn) and 2.73x10−3 mol of tungsten trioxide (WO3). We confirmed the obtaining of the pure phase for beta (β-SnWO4) with cubic structure and space group P213 in samples SW-4h and SW-5h, using X-ray diffraction characterization techniques and structure refinement. As well as, a phase mixture between β-SnWO4 and SnW3O9 in samples SW-2h and SW-3h. Furthermore, the structure had its vibrational modes analyzed via Raman spectroscopy, with the mode at 950cm−1 characteristic of β-SnWO4 identified. Its morphology was studied using scanning electron microscopy micrographs and energy dispersive spectroscopy to visualize the evolution of morphology caused by HEBM. Its optical characteristics were measured using the diffuse reflectance spectroscopy and colorimetry technique, identifying the SW-5h sample with the smallest bandgap (2.5 eV) and yellowish color, in accordance with other research. In addition, its photocatalytic performance was studied through the degradation of the cationic dye Rhodamine-b, achieving a degradation of 61% for SW-5h. Therefore, our study enabled a low-cost and fast-processing approach to obtain a material with properties of technological interest.