REJANE MARIA PEREIRA DA SILVA
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Artigo IPEN-doc 30039 S-doped ZnO photoelectrode modified with silver and platinum nanoparticles and their photocatalytic activity for progesterone degradation2024 - LUIS, JAILSON S.; EDUARDO, SAMUEL S.; COSTA, MARIA J.S.; BRANDAO-LIMA, LUCIANO C.; ANTUNES, RENATO A.; FERREIRA, RAPHAEL O.; SILVA, REJANE M.P.; SANTOS, REGINALDO S.Zinc oxide doped with sulfur (ZnO-S) has presented improved photocatalytic activity under visible irradiation. In this work, ZnO-S film was efficiently prepared by thermal decomposition from zinc sulfide (ZnS) in an oxidizing atmosphere. X-ray diffraction analysis (XRD) showed ZnS phase transformation occurred from cubic sphalerite to ZnO hexagonal wurtzite at temperatures between 500 and 600 °C. ZnO-S electrodes prepared onto a transparent conductive substrate were modified by silver (Ag0) or platinum (Pt0) nanoparticles (NPs). X-ray photoelectron spectroscopy (XPS) confirmed that sulfur was incorporated into ZnO structure. Field Emission Gun-Scanning Electron Microscope (FEG-SEM) images showed that occur a drastic modification in the particle morphology of the films treated at distinct temperatures. Photoelectrochemical investigation displayed a negative photopotential (∆E<0) for all photoelectrode investigated as well as superior photocurrents for samples modified with metallic Ag0 and Pt0 NPs. In order to investigate the photoelectroactivity, ZnO-S6, Ag0/ZnO-S6, Pt0/ZnO-S6 and commercial ZnO electrodes were used to degrade progesterone solution under polychromatic irradiation. The superior performances were observed for ZnO-S films functionalized with Ag0 or Pt0. Therefore, the results showed advances in the degradation of organic contaminants in the water treatment process and possible contributions to a better use of solar radiation.Artigo IPEN-doc 29921 Crystalline S-doped TiO2 photoanodes from amorphous titanium oxysulfide (TiOxSy) for photo-oxidation reactions2023 - PITOMBEIRA, DANIEL R.S.; COSTA, MARIA J.S.; ANTUNES, RENATO A.; FERREIRA, RAPHAEL O.; SILVA, REJANE M.P.; SANTOS, REGINALDO S.S-doped TiO2 films were prepared by oxidation annealing of amorphous titanium oxysulfide (TiOxSy) at different temperatures. According to the X-ray diffraction patterns, the films calcined at temperatures of 300–600 ◦C showed only anatase phase, while the uncalcined sample was amorphous. The chemical composition of synthesized TiOxSy was estimated by X-ray photoelectron spectroscopy (XPS). High-resolution S 2p spectra showed S 2 bonds at 163.47 eV for the amorphous sample. The intensity of this signal decreased after heat treatment. Raman spectroscopy indicated an organization of the material structure with heat treatment of the material. Furthermore, optical characterization revealed that sulfur as dopant into the anatase TiO2 structure, shifted light absorption from ultraviolet to the visible region. Photoeletrochemical studies developed under polychromatic irradiation revealed superior photocurrents for samples calcined at 600 ◦C, with n-type behavior, adequate for photo-oxidation reactions.Artigo IPEN-doc 27829 Use of amperometric and potentiometric probes in scanning electrochemical microscopy for the spatially-resolved monitoring of severe localized corrosion sites on aluminum alloy 2098-T3512021 - SILVA, REJANE M.P. da; IZQUIERDO, JAVIER; MILAGRE, MARIANA X.; BETANCOR-ABREU, ABENCHARA M.; COSTA, ISOLDA; SOUTO, RICARDO M.Amperometric and potentiometric probes were employed for the detection and characterization of reactive sites on the 2098-T351 Al-alloy (AA2098-T351) using scanning electrochemical microscopy (SECM). Firstly, the probe of concept was performed on a model Mg-Al galvanic pair system using SECM in the amperometric and potentiometric operation modes, in order to address the responsiveness of the probes for the characterization of this galvanic pair system. Next, these sensing probes were employed to characterize the 2098-T351 alloy surface immersed in a saline aqueous solution at ambient temperature. The distribution of reactive sites and the local pH changes associated with severe localized corrosion (SLC) on the alloy surface were imaged and subsequently studied. Higher hydrogen evolution, lower oxygen depletion and acidification occurred at the SLC sites developed on the 2098-T351 Al-alloy.