RODRIGO TEIXEIRA BENTO

RODRIGO TEIXEIRA BENTO

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Visible-light photocatalytic activity and recyclability of N-doped TiO2 films grown by MOCVD
2020 - 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.
Effect of growth parameters on the photocatalytic performance of TiO2 films prepared by MOCVD
2020 - MARCELLO, BIANCA A.; CORREA, OLANDIR V.; BENTO, RODRIGO T.; PILLIS, MARINA F.
The present study evaluated the main factors that influence the photocatalytic activity of titanium dioxide (TiO2) films grown by metalorganic chemical vapor deposition (MOCVD) at 400 and 500 °C, in different growth times. The photocatalytic behavior was analyzed by measuring the methyl orange dye degradation at different pH values. Structural and morphological characteristics, and the recyclability of the catalysts for several cycles were also investigated. Anatase phase was identified in all films. The higher photodegradation performances were obtained at acidic pH. The results demonstrated that the photocatalyst thickness is an important parameter in heterogenous photocatalysis. The best photocatalytic result occurred for the 395 nm-thick TiO2 film grown at 400 °C, which presented 65.3% of the dye degradation under UV light. The recyclability experiments demonstrated that the TiO2 films grown by MOCVD present a great stability after several photocatalytic cycles, which allows their practical application for water treatment with high efficiency.
Characterization and photocatalytic behavior of TiO2 thin films grown by MOCVD process
2017 - BENTO, RODRIGO T.; OLIVEIRA, EDUARDO C. de; SZURKALO, MARGARIDA; CORREA, OLANDIR V.; PILLIS, MARINA F.
This research aims to evaluate the influence of the thickness on the photocatalytic behavior of TiO2 thin films grown at 400ºC by metalorganic chemical vapor deposition. Titanium dioxide films with 280 and 468 nm of thickness were grown on borosilicate substrates. The photocatalytic behavior was evaluated by monitoring the degradation of methyl orange dye under UV light for 2h. The results show that both films presented anatase crystalline phase and that increasing the thickness the grain size and the roughness were also increased. The best photocatalytic performance was attributed to the film of 468 nm of thickness that exhibited 40% of dye degradation after 2h under UV light.
Morphological characterization of N-doped TiO2 thin films
2017 - 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.
Caracterização microestrutural de filmes finos de TiO2
2017 - BENTO, RODRIGO T.; FERRUS FILHO, ANDRE; PILLIS, MARINA F.
Filmes finos de dióxido de titânio vêm sendo utilizados em diversas aplicações tecnológicas, desde revestimentos autolimpantes e bactericidas, até células solares e fotocatalisadores. O TiO2 apresenta polimorfismo em três fases cristalinas: anatase, broquita e rutilo, cada uma com propriedades físicas e químicas específicas. O presente trabalho apresenta o resultado do somatório de experiências desenvolvidas pelo grupo de pesquisa do Laboratório de Filmes Finos e Nanoestruturas do IPEN (Brasil), analisando por meio dos respectivos estudos a influência da temperatura de deposição e substrato sobre a morfologia dos filmes obtidos. Os filmes de TiO2 foram crescidos através da técnica de deposição química de organometálicos em fase vapor (MOCVD), sobre substratos de borossilicato, a 400 e 500°C, e substratos Si(100) nas temperaturas de 400, 500, 600 e 700°C. Observando-se os espectros de difração de raios-X dos filmes, foi verificado que a 400 e 500°C há a presença apenas da fase anatase, enquanto que a 600°C pode-se identificar as fases anatase e rutilo. O filme crescido a 700°C apresentou, além de anatase e rutilo, a fase broquita. Foi observadoque a velocidade de crescimento dos filmes aumenta com a temperatura até 500°C e, a partir disso diminui, aspecto característico da curva do processo, que indica haver uma mudança de mecanismo de crescimento.