RODRIGO TEIXEIRA BENTO
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Artigo IPEN-doc 26655 Effect of nitrogen-doping on the surface chemistry and corrosion stability of TiO2 films2020 - SOUZA FILHO, EDVAN A. de; PIERETTI, EURICO F.; BENTO, RODRIGO T.; PILLIS, MARINA F.TiO2 and N-doped TiO2 films were grown on AISI 316 stainless steel substrates and on Si (100) by metallorganic chemical vapor deposition (MOCVD) at 400 ā¦C and 500 ā¦C. X-ray photoelectron spectroscopy, scanning electron microscopy, and contact angle techniques were used to characterize de films. The corrosion behavior was assessed by monitoring the open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization tests in 3.5 wt% NaCl solution at room temperature. The results show that 6.18 at% of nitrogen was introduced in the films grown at 400 ā¦C and 8.23 at% at 500 ā¦C, and that besides TiO2, nitrogen phases were identified. All the films are hydrophilic and the contact angles varied from 48ā¦ to 72ā¦. The films presented good homogeneity, low porosity and rounded grains in the range of 40ā90 nm. The RMS roughness varied between 5.5 and 18.5 nm. Titanium dioxide films grown at 400 ā¦C showed better corrosion resistance than those grown at 500 ā¦C due to its compact morphology. Nitrogen-doping was not efficient to protect the substrate from corrosion.Artigo IPEN-doc 26485 Photocatalytic activity of undoped and sulfur-doped TiO2 films grown by MOCVD for water treatment under visible light2019 - BENTO, RODRIGO T.; CORREA, OLANDIR V.; PILLIS, MARINA F.Titanium dioxide ceramic coatings have been used as catalysts in green technologies for water treatment. However, without the presence of a dopant, its photocatalytic activity is limited to the ultraviolet radiation region. The photocatalytic activity and the structural characteristics of undoped and sulfur-doped TiO2 films grown at 400 Ā°C by metallorganic chemical vapor deposition (MOCVD) were studied. The photocatalytic behavior of the films was evaluated by methyl orange dye degradation under visible light. The results suggested the substitution of Ti4+ cations by S6+ ions into TiO2 structure of the doped samples. SO4 2ā groups were observed on the surface. S-TiO2 film exhibited good photocatalytic activity under visible light irradiation, and the luminous intensity strongly influences the photocatalytic behavior of the S-TiO2 films. The results supported the idea that the sulfur-doped TiO2 films grown by MOCVD may be promising catalysts for water treatment under sunlight or visible light bulbs.