Browsing by Author "Santos, Evelyn C.S."

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    BiOBr/ZnWO4 heterostructures: An important key player for enhanced photocatalytic degradation of rhodamine B dye and antibiotic ciprofloxacin
    (Elsevier Ltd, 2022-11-07T00:00:00) Santana, Rafael W.R.; Lima, A.E.B.; Souza, Luiz K.C. de; Santos, Evelyn C.S.; Santos, C.C.; Menezes, A.S. de; Sharma, Surender K.; Cavalcante, L.S.; Maia da Costa, Marcelo E.H.; Sales, T.O.; Jacinto, Carlos; Luz, G.E.; Almeida, M.A.P.
    We report a facile synthesis of p-BiOBr/n-ZnWO4 heterostructures by hydrothermal/precipitation method as an important key player to enhance the photocatalytic degradation of Rhodamine B (RhB) dye and ciprofloxacin antibiotic. The structural and microstructural features confirm that p-BiOBr/n-ZnWO4 heterostructures display a mixed tetragonal/monoclinic phase with the presence of several n-ZnWO4 nanocrystals on the surface of petals of flower-like p-BiOBr microcrystals. X-ray photoluminescence (XPS) analysis of BiOBr exhibits the existence of Bi, O, and Br, whereas BiOBr/ZnWO4-5%, in addition to Bi, O, and Br, consist of signature of Zn and W. UV�Visible spectra of p-BiOBr/n-ZnWO4-5% showed better absorption than p-BiOBr and n-ZnWO4, which displayed an enhanced collection of photons in the heterojunction. An intense photoluminescence emission at room temperature was observed for p-BiOBr microcrystals as compared to p-BiOBr/n-ZnWO4. We observed the best photocatalytic activity for p-BiOBr/n-ZnWO4-2.5% in the degradation of RhB dye at 99.4% in 25 min and CIP antibiotic at 58.2% in 170 min, which is assigned due to high surface area SBET (13 m2/g), pore size, providing active catalytic sites for bonding chemical and surface interaction and bonding chemical between the bromide/oxides. Finally, we have investigated the use of scavengers for isopropanol, benzoquinone, and sodium azide, which proves that the hydroxyl (�OH) and superoxide (O2?) radicals as the foremost reactive oxygen spicies (ROS) in photocatalytic degradation of RhB dye and antibiotic CIP. � 2022 Elsevier Ltd
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    Enhanced photocatalytic activity of BiOBr/ZnWO4 heterojunction: A combined experimental and DFT-based theoretical approach
    (Elsevier B.V., 2023-03-28T00:00:00) Andrade, Alana O.C.; Lacerda, Lu�s Henrique da Silveira; Lage J�nior, M.M.; Sharma, Surender K.; Maia da Costa, M.E.H.; Alves, Odivaldo C.; Santos, Evelyn C.S.; dos Santos, C.C.; de Menezes, A.S.; San-Miguel, Miguel Angel; Filho, Francisco Moura; Longo, Elson; Almeida, Marcio A.P.
    We report a successful fabrication of BiOBr/ZnWO4 heterojunction with enhanced photocatalytic performance for degrading Rhodamine B dye validated by joint experimental and theoretical approaches. The structural and microstructural analysis indicate that the heterostructures consist of a mixed tetragonal/monoclinic phase with enhanced surface area, which is crucial for photocatalysis. The results indicate increased photocatalytic activity for heterojunctions since BiOBr/ZnWO4 heterostructure showed a better degradation rate for Rhodamine B dye as compared to BiOBr due to higher surface area, pore size, and better photogenerated electron-hole pair separation efficiency. Additional analyses using isopropanol, benzoquinone, and sodium azide scavengers analysis were performed, showing that superoxide radicals (O2?) as the main responsible for the photocatalytic degradation of investigated materials. The theoretical analysis offers a complete overview of the composition and electronic structure of the interface. � 2023 Elsevier B.V.