Significant effect of lanthanide doping on the texture and properties of nanocrystalline mesoporous TiO2

Zhang, Yuhong; Zhang, Huaxing; Xu, Yuchen; Wang, Yanguang

doi:10.1016/j.jssc.2004.05.026

Cited by 164 publications

(89 citation statements)

References 37 publications

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“…Indeed, as previously reported, the Eu III cations inhibit the anatase-to-rutile allotropic phase transformations. [5] The determination of the europium location(s) within the matrix might provide a handy tool for enhancing important properties, such as the photocatalytic characteristics and reactivity of titania, the performance of sensors, or the degree of charge-transfer coupling. Here, we apply various experimental Herein, Eu III -doped 3D mesoscopically ordered arrays of mesoporous and nanocrystalline titania are prepared and studied.…”

Section: Introductionmentioning

confidence: 99%

Europium‐Doped Mesoporous Titania Thin Films: Rare‐Earth Locations and Emission Fluctuations under Illumination

et al. 2008

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Herein, Eu(III)-doped 3D mesoscopically ordered arrays of mesoporous and nanocrystalline titania are prepared and studied. The rare-earth-doped titania thin films-synthesized via evaporation-induced self-assembly (EISA)-are characterized by using environmental ellipsoporosimetry, electronic microscopy (i.e. high-resolution scanning electron microscopy, HR-SEM, and transmission electron microscopy, HR-TEM), X-ray diffraction, and luminescence spectroscopy. Structural characterizations show that high europium-ion loadings can be incorporated into the titanium-dioxide walls without destroying the mesoporous arrangement. The luminescence properties of Eu(III) are investigated by using steady-state and time-resolved spectroscopy via excitation of the Eu(III) ions through the titania host. Using Eu(III) luminescence as a probe, the europium-ion sites can be addressed with at least two different environments within the mesoporous framework, namely, a nanocrystalline environment and a glasslike one. Emission fluctuations ((5)D(0)-->(7)F(2)) are observed upon continuous UV excitation in the host matrix. These fluctuations are attributed to charge trapping and appear to be strongly dependent on the amount of europium and the level of crystallinity.

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Section: Introductionmentioning

confidence: 99%

Europium‐Doped Mesoporous Titania Thin Films: Rare‐Earth Locations and Emission Fluctuations under Illumination

et al. 2008

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“…Os elementos da série dos lantanídeos apresentam facilidade para a complexação com bases de Lewis [56][57][58] . Desta forma, a dopagem de fotocatalisadores com o cério aumenta a capacidade de adsorção dos poluentes, (tais como ácidos orgânicos, aldeídos, aminas e álcoois) sobre a superfície do fotocatalisador, o que pode favorecer o processo de fotodegradação dos poluentes 57,58 .…”

Section: Figura 3 Representação Do Mecanismo De Atuação Do Catalisadunclassified

Cério: propriedades catalíticas, aplicações tecnológicas e ambientais

Martins¹,

Hewer²,

Freire³

2007

Quím. Nova

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Recebido em 13/11/06; aceito em 2/3/07; publicado na web em 25/10/07 CERIUM: CATALYTIC PROPERTIES, TECHNOLOGICAL AND ENVIRONMENTAL APPLICATIONS. Cerium based-compounds have great importance in a wide range of technological applications, such as: fuel cell devices development; metallurgic processes, petroleum refining; glass and ceramic production. Recently, its catalytic properties have been also explored for environmental applications, especially those to prevent or to control atmospheric and water pollution. Subjects covered in this work include a brief description of the fundaments of cerium catalytic properties and some relevant technological applications. Special attention is given to its photocatalytic activity and its ability to degrade pollutants. Recent results and future prospect about these applications are also evaluated.Keywords: lanthanide; catalysis; heterogeneous photocatalyst. INTRODUÇÃOO cério, elemento químico de número atômico 58, é um dos 15 elementos classificados como lantanídeos (La ao Lu), que juntamente com Sc e Y formam a família das Terras Raras. Cério é o mais abundante das Terras Raras. Sua abundância na crosta terrestre é da ordem de 60 ppm, o que o torna o 26º elemento em freqüência de ocorrência, sendo quase tão abundante quanto cobre e níquel. Apesar de o cério ser o lantanídeo de maior ocorrência, é encontrado em muitos minerais somente em níveis traço, sendo a bastinasita e monasita os minerais mais importantes como fonte de cério e suprem a maior parte da demanda mundial deste elemento [1][2][3][4][5][6] . Estes dois minerais, dependo da localidade dos depósitos, possuem cerca de 65-70% (bastinasita) e 49-74% (monasita) de terras céricas (La-Gd), sendo que, considerando-se a porcentagem de lantanídeos na bastinasita e monasita como 100%, a quantidade de CeO 2 corresponde a aproximadamente 49 e 47%, respectivamente 5 .O cério, que tem a configuração eletrônica [Xe]4f 1 5d 1 s 2 , é muito eletropositivo e suas interações são predominantemente iônicas devido ao baixo potencial de ionização (3,49 kJ mol -1 ) para a remoção dos três primeiros elétrons 1-3 . Assim como outros lantanídeos, o estado de oxidação mais estável deste elemento é o (+III). O cério trivalente tem propriedades semelhantes a outros íons lantanídeos com mesmo estado de oxidação 3,5 , com exceção da sua fácil oxidação para Ce 4+ e instabilidade em ar e água. Seus sais, em geral, mais estáveis que os de Ce 4+ , são pouco hidrolisáveis e muito utilizados como precursores para vários compostos de cério [1][2][3][4][5][6] . Diferentemente dos demais elementos dessa classe, o estado de oxidação (+IV) também é estável, principalmente em virtude da configuração eletrônica semelhante à de um gás nobre ([Xe]4f 0 ). Este elemento é o único lantanídeo, no estado tetravalente, estável em solução aquosa, porém a influência da carga maior e tamanho iônico menor faz com que os sais do íon Ce 4+ sejam hidrolisados em soluções aquosas com mais facilidade que o íon Ce 3+ e, em conseqüência disso, estas soluções são fortemente ác...

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“…: lanthanide ions was kept as 99: 1 for all lanthanide ions -doped nanoparticles which still maintained a single anatase modification even at high temperature ≤ 900°C [14]. …”

Section: +mentioning

confidence: 99%

“…acids, amines, aldehydes, alcohols, thiols, …..etc) in the interaction of these functional groups with the ƒ-orbitals of the lanthanides. Particularly, REmodified TiO2 nanoparticles become of current importance for maximizing the efficiency of photocatalytic reactions, increase the stability of anatase phase and prevent the segregation of TiO2 [13][14][15][16]. Thus, incorporation of lanthanide ions into a TiO2 matrix could provide a means to concentrate on the organic pollutant at the semiconductor surface and consequently enhance the photoactivity of titania [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of the Photocatalytic Properties of Titania Nanoparticles by Doping Lanthanide Ions

El‐Bahy

Ismail

Mohamed

2007

Al-Azhar Bulletin of Science

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Lanthanide ions (La 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ , and Yb 3+ )-doped TiO2 nanoparticles were successfully synthesized by sol-gel method to enhance the photocatalytic activity of the developed materials. The structural features of TiO2 and lanthanide ions-doped TiO2 fired at 550ºC were investigated by XRD, UV-diffuse reflectance, and nitrogen adsorption measurements. The effect of lanthanide ions-doped TiO2 on the photoactivity was evaluated by the degradation of direct blue dye (DB 53) as a probe reaction. Our findings indicated that XRD data verified the formation of typical characteristic anatase reflections without any separate dopant-related peaks in all the prepared lanthanide ion-doped TiO2 nanoparticles. The particle size of lanthanide ions-doped TiO2 nanoparticles was smaller than pure TiO2 indicating the improvement of its surface morphology. The results indicated that Gd 3+ -TiO2 has the lowest bandgap and particle size and the highest surface area and pore volume (Vp) as well. The photocatalytic behavior of lanthanide ions-doped TiO2 was tested for oxidation of DB 53 in the presence of UV light at λ = 365 nm. It was found that Gd 3+ -TiO2 is the most effective catalyst in the photocatalytic activity studies. That might be due to its special characteristics of particle size, surface texture and bandgap properties. Our results should provide a significant contribution to the understanding of the chemistry of lanthanide iondoped TiO2 systems. Details of the synthesis procedure and results of the characterization studies of the produced lanthanide ions-TiO2 are presented in this paper.

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Significant effect of lanthanide doping on the texture and properties of nanocrystalline mesoporous TiO2

Cited by 164 publications

References 37 publications

Europium‐Doped Mesoporous Titania Thin Films: Rare‐Earth Locations and Emission Fluctuations under Illumination

Europium‐Doped Mesoporous Titania Thin Films: Rare‐Earth Locations and Emission Fluctuations under Illumination

Cério: propriedades catalíticas, aplicações tecnológicas e ambientais

Enhancement of the Photocatalytic Properties of Titania Nanoparticles by Doping Lanthanide Ions

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