Fe-doped nanostructured titanates synthesized in a single step route

Costa, Antonio Mario Leal Martins; Marinković, Bojan A.; Suguihiro, N. M.; Smith, David J.; Costa, M.E.H. Maia da; Paciornik, Sidnei

doi:10.1016/j.matchar.2014.11.029

Cited by 10 publications

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“…A newly proposed approach for synthesis of titanate nanotubes with corrugated, stepped, layered structure [25] and LTs nanosheets [26][27][28] through alkaline hydrothermal treatment of an abundant precursor such as raw mineral sand provides a straightforward route for preparation of LTs nanosheets consisting of only a few stacked layers and with lateral (planar) lengths not larger than a few tens to several hundreds of nanometers. Although Maluangnont et al [29] demonstrated recently that it is possible to control the lateral size of LTs originally synthesized by solid state route, through an additional step including the correct choice of tetraalkylammonium cation, tetraalkylammonium-to-proton ratio and the mode of the ionexchange reaction, the lateral dimension of LTs is generally predefined by the size of the precursor crystals [23].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it is advantageous to control dimensions of LTs crystals already in the synthesis stage. The LTs nanosheets currently synthesized through alkaline hydrothermal treatment of mineral sands have a high surface area (~80 m 2 g −1 ) and could contain more or less Na + /H + depending on the washing stage [26][27][28]. Jardim et al [26] proposed that Fe 3+ , originated from the dissolved ilmenite mineral sand, adopts an octahedral coordination inside the lepidocrocite-like host layers exchanging partially for Ti 4+ , forming Na x − y H y Ti 2 − x Fe x O 4 ·nH 2 O nanosheets.…”

Section: Introductionmentioning

confidence: 99%

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Lepidocrocite-like ferrititanate nanosheets and their full exfoliation with quaternary ammonium compounds

et al. 2015

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lepidocrocite-like ferrititanate nanosheets and their full exfoliation with quaternary ammonium compounds

et al. 2015

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“…A não estequiometria da estrutura lepidocrocita das nanofolhas de titanatos sugere um possível mecanismo de controle da densidade de carga de intercamada, sendo a mesma uma parte importante nos processos de funcionalização por intercalação e esfoliação (43,44 [48].…”

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“…Existem também relatos na literatura da preparação de nanoestruturas a partir de rutilo ou de areias minerais ilmeníticas [48,52]. Quando a areia mineral ilmenítica é tratada em condições alcalinas hidrotérmicas a temperaturas ≤ 150 °C, nanofolhas de ferrititanato com estrutura lepidocrocita são formadas [42,48] …”

Section: Puc-rio -Certificação Digital Nº 1321796/caunclassified

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Nanohíbrido Mesoporoso Sensível À Luz Visível Preparado a Partir De Ferrititanato Do Tipo Lepidocrocita Acoplado a Um Complexo De Transferência De Carga E Empregado Na Conversão Fotocatalítica De Um Gás Poluente

ESTEBAN¹

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Nanohíbrido mesoporoso sensível à luz visível preparado a partir de ferrititanato do tipo lepidocrocita acoplado a um complexo de transferência de carga e empregado na conversão fotocatalítica de um gás poluente O foco do presente estudo é desenvolvimento de uma heteroestrutura de dois semicondutores com capacidade de reduzir a taxa de recombinação elétron/buraco mediante uma intensa separação de carga, e ao mesmo tempo sendo sensível ao espectro de luz visível. A separação de carga estaria sendo alcançada por meio da injeção de elétrons livres dentro da banda de condução (BC) do TiO 2 na forma de anatásio, provenientes do orbital molecular mais alto ocupado (HOMO) da acetilacetona (Acac), ligada às partículas de anatásio, seguida da sua injeção dentro dos orbitais d desocupados do Fe 3+ localizados dentro da banda de energia proibida das nanofolhas de ferrititanatos. Tese de DoutoradoAo mesmo tempo a absorção da luz visível poderia ser assegurada através das nanofolhas de ferrititanatos, considerando-se a interação dos níveis energéticos do Fe 3+ com a luz e as bandas de valência e condução, bem como pela formação de complexo de transferência de carga (CTC), entre as nanopartículas de anatásio e Acac. Os nanohíbridos mesoporosos (as heteroestruturas) são produzidos pelas diferentes rotas de junção de nanofolhas de ferrititanato, obtidas da areia mineral ilmenítica e posteriormente esfoliadas, com nanopartículas de TiO 2 modificadas com acetilacetona, estes útlimos formando CTC. As técnicas de caraterização empregadas tais como adsorção-dessorção de N 2 , espectroscopia de emissão de fotoluminescência (PL) e espectroscopia de refletância difusa (DRS), entre outras, confirmaram a formação das heteroestruturas mesoporosas sensíveis à luz visível e com forte mecanismo de separação de cargas. A fotodegradação do gás poluente NO no espectro de luz-visível por meio de vários nanohíbridos mesoporosos (fotocatalisadores) mostrou-se bem sucedida, exibindo uma eficiência até 7 vezes superior em comparação à atividade do material fotocatalítico padrão TiO 2 (P-25 da Degussa). Palavras-chaveHeteroestruturas; Remediação ambiental; Estruturas em camadas; TiO 2 ; Esfoliação. This work focues on the development of a heterostructure composed by two semiconductors, capable to decrease the electron/hole recombination rate through a robust charge separation, and at the same time, this nanohybrid is sensitive to visible light spectrum. The charge separation is achieved by the injection of free electrons within the conduction band (BC) of TiO 2 in anatase form, which come from the highest-occupied-molecular-orbital (HOMO) of acetylacetone (Acac), linked to the anatase nanoparticles, followed by the injection into unoccupied Fe 3+ d-orbital within band-gap energy of the ferrititanate nanosheets. Additionally, the absorption of visible light could be assured by ferrititanate nanosheets, considering the interaction of the energy levels of Fe 3+ with visible light and the valence and conduction bands, as well as, the formation of the cha...

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Visible light sensitive mesoporous nanohybrids of lepidocrocite-like ferrititanate coupled to a charge transfer complex: Synthesis, characterization and photocatalytic degradation of NO

Habran

Pontón

Mančić

et al. 2018

Journal of Photochemistry and Photobiology A: Chemistry

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The efficiency of photo-oxidation of pollutants catalysed by semiconductors is still limited for real-world applications due to several drawbacks, such as a) insufficient absorption of visible radiation, which predominates in solar spectrum, b) rapid free electron to hole recombination, c) small surface area, built from equilibrium crystallographic facets with low adsorption capacities and d) photo-corrosion. The present study disclosures new mesoporous heterostructures, built from exfoliated lepidocrocite-like ferrititanates and TiO 2 (anatase)-acetylacetone charge transfer complex, capable of reducing free electron-to-hole recombination rate through a robust charge separation and sensitive to the visible light spectrum. The synthesis route is based on soft-chemistry and low temperature calcination at 300°C. Two different partially pillarized heterostructures, denoted as HM-1 and HM-2, have been synthesized. It was observed that the heterostructure HM-1 was four times more active toward photocatalytic degradation of NO gas in comparison to the benchmark photocatalytic material P25. The lower activity of the heterostructure HM-2, comparable to that of P-25, was attributed to the high value of Urbach energy that indicates high number of defect sites within energy band-gap of the constituent semiconductor components. [Ti] anatase/[Ti] ferrititanate mol ratio might also play a role in photocatalytic efficiency.

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Fe-doped nanostructured titanates synthesized in a single step route

Cited by 10 publications

References 28 publications

Lepidocrocite-like ferrititanate nanosheets and their full exfoliation with quaternary ammonium compounds

Lepidocrocite-like ferrititanate nanosheets and their full exfoliation with quaternary ammonium compounds

Nanohíbrido Mesoporoso Sensível À Luz Visível Preparado a Partir De Ferrititanato Do Tipo Lepidocrocita Acoplado a Um Complexo De Transferência De Carga E Empregado Na Conversão Fotocatalítica De Um Gás Poluente

Visible light sensitive mesoporous nanohybrids of lepidocrocite-like ferrititanate coupled to a charge transfer complex: Synthesis, characterization and photocatalytic degradation of NO

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