Estudo das propriedades fotoeletrocatalíticas dos materiais heteroestruturados à base de CuWO4

Abstract

Environmental photoelectrocatalysis is an area in potential development and has been applied in different processes, such as: degradation and detection of emerging organic compounds, H2 production and CO2 reduction. In this sense, a study of the photoelectrocatalytic properties of heterostructured materials based on CuWO4 was carried out. Firstly, the morphology was evaluated, as well as the structural analysis and band gap energy estimation of pure CuWO4 calcined at different calcination temperatures 300, 400 and 500oC by the techniques of Scanning Electron Microscopy with field emission (SEM-FEG), Ray Diffractometry X (XRD) and Diffuse Reflectance Spectroscopy in the Ultraviolet-Visible Region (UV-Vis ERD), respectively. From these results, the one that obtained the best crystallinity was chosen, an important characteristic in the photocatalysis activity, in this case the CuWO4 of 500oC. Photocatalytic assays were performed for the degradation of methylene blue as well as with Ag3PO4 and the heterojunction of the two semiconductors. The heterojunction showed the best degradation time, followed by the pure semiconductors Ag3PO4 and CuWO4. Finally, photoelectrocatalytic tests were carried out with CuWO4 and its heterojunction with Ag3PO4 deposited on a conductive substrate (fluorine-doped tin oxide, FTO) together with substances known as scavengers to evaluate the oxidation and reduction mechanism and subsequently in the presence of nitrite and diuron. The FTO/CUWO4 electrode proved to be active for the detection of nitrite, which is an intermediate species of nitrogen and of public health interest since it is related to diseases and the formation of nitrosamines. The FTO/CuWO4/Ag3PO4 electrode showed activity for detecting the pesticide diuron. Therefore, these electrodes are promising in the detection of emerging substances via photoelectrocatalysis.