OLANDIR VERCINO CORREA
6 resultados
Resultados de Busca
Agora exibindo 1 - 6 de 6
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.Resumo IPEN-doc 26538 Performance of nitrogen-doped TiO2 films grown by MOCVD for water treatment under visible light2019 - OLIVEIRA, EDUARDO C. de; BENTO, RODRIGO T.; CORREA, OLANDIR V.; PILLIS, MARINA F.Titanium dioxide is a semiconductor employed as catalyst in the photodegradation of organic pollutants and bacteria. However, due to its large band gap TiO2 only can be excited by UV light. Recently, TiO2 doping with metals or nonmetals elements has been extensively exploited to allow its use under visible light. In the present work, nitrogen-doped and undoped TiO2 films were grown on borosilicate substrates at 400 ° C for 60 minutes by metallorganic chemical vapor deposition (MOCVD). Titanium isopropoxide IV was used as precursor of titanium and oxygen, and ammonia as nitrogen source. Ammonia was incorporated into the films in three different quantities during the growth. The effect of nitrogen contents on the structural and surface properties of TiO2 catalysts was evaluated. Both doped and undoped films presented rounded well-defined anatase grains. XPS analyses revealed that values of 1.6; 2.4 and 7.3 at% of nitrogen were incorporated into the films by varying the ammonia flux during the growth. Degradation assays have shown that nitrogen-doped TiO2 films exhibited high photocatalytic activity under visible light irradiation. Undoped films did not present activity in this condition. The better catalytic performance under visible light, 55% of dye degradation, was attributed to the film containing 2.4 at% of nitrogen. The results suggest that nitrogen-doped TiO2 catalysts grown by MOCVD have great potential to be used in the treatment of water under sunlight.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 25006 Characterization and photocatalytic behavior of TiO2 thin films grown by MOCVD process2017 - 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.Artigo IPEN-doc 25005 Synthesis and characterization of TiO2 films obtained by sol-gel method2017 - SZURKALO, MARGARIDA; OLIVEIRA, EDUARDO C. de; CORREA, OLANDIR V.; BENTO, RODRIGO T.; PILLIS, MARINA F.Borosilicate coated titanium dioxide thin films were produced by the sol-gel method. The films were calcinated at 450°C for 20 minutes for crystalization. X-ray diffration analyses show that before the heat treatment the film was amorphous and after that it crystallized in anatase phase presenting mean grain size of 34 nm and RMS roughness of 8 nm. The crystallized film was used as photocatalist in the degradation of methyl orange dye presenting an efficiency of 25% after 2h under UV light.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.