RODRIGO TEIXEIRA BENTO
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Artigo IPEN-doc 27557 Visible-light photocatalytic activity and recyclability of N-doped TiO2 films grown by MOCVD2020 - OLIVEIRA, E.C. de; BENTO, R.T.; CORREA, O.V.; PILLIS, M.F.Nitrogen-doped TiO2 films were grown on borosilicate glass substrates at 400 °C by the metallorganic chemical vapor deposition (MOCVD) for removing dye from water under visible light. The effect of N-doping on the structural, surface, and photocatalytic properties of films was evaluated. X-ray photoelectron spectroscopy (XPS) analyses revealed that 1.56 and 2.44 at% of nitrogen were incorporated into the films by varying the NH3 flux during the growth. Methyl orange dye degradation experiments showed that the N-doped films presented photoactivity under visible light. The film containing 2.44 at% of nitrogen exhibited the best photocatalytic behavior, with 55% of efficiency. Recyclability tests under visible light showed that the film efficiency dropped gradually after each test. N-TiO2 films grown by MOCVD have the potential to be used in environmental applications by removing pollutants using a green method under sunlight or even under internal illumination, although its reuse is limited.Artigo IPEN-doc 26759 Caracterização morfológica de filmes de TiO2 dopados com nitrogênio crescidos por MOCVD2019 - OLIVEIRA, E.C. de; CORREA, O.V.; BENTO, R.T.; COTINHO, S.P.; SANTOS, T.F. dos; PILLIS, M.F.O método de deposição química de organometálicos em fase vapor (MOCVD) foi utilizado para o crescimento de filmes de dióxido de titânio (TiO2) e TiO2 dopado com nitrogênio. Os filmes foram crescidos a 400 °C sobre substratos de vidro borossilicato. Isopropóxido de titânio IV foi utilizado como precursor de titânio e de oxigênio, e amônia (NH3) como fonte de nitrogênio. Análises por microscopia de força atômica (AFM) mostraram que ambos os filmes apresentaram grãos bem definidos e arredondados. Todos os filmes são formados apenas pela fase cristalina anatase. Os resultados mostraram que a dopagem com nitrogênio resultou em uma diminuição no tamanho médio de grão e na rugosidade superficial.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 ◦C and 500 ◦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 ◦C and 8.23 at% at 500 ◦C, and that besides TiO2, nitrogen phases were identified. All the films are hydrophilic and the contact angles varied from 48◦ to 72◦. The films presented good homogeneity, low porosity and rounded grains in the range of 40–90 nm. The RMS roughness varied between 5.5 and 18.5 nm. Titanium dioxide films grown at 400 ◦C showed better corrosion resistance than those grown at 500 ◦C due to its compact morphology. Nitrogen-doping was not efficient to protect the substrate from corrosion.Artigo IPEN-doc 24951 Morphological characterization of N-doped TiO2 thin films2017 - OLIVEIRA, EDUARDO C. de; SZURKALO, MARGARIDA; CORREA, OLANDIR V.; BENTO, RODRIGO T.; PILLIS, MARINA F.Metallorganic chemical vapor deposition was used to grown TiO2 and N-doped TiO2 on borosilicate substrates at 400°C. Titanium isopropoxide IV was used as titanium and oxygen precursors and ammonia as nitrogen source. Analyses by atomic force microscopy showed that both films presented rounded well-defined grains. The results showed that nitrogen doping resulted in a decrease in the mean grain size and in the surface roughness.