NIOBIUM OXIDES: AN OVERVIEW OF THE SYNTHESIS OF Nb<sub>2</sub>O<sub>5</sub>AND ITS APPLICATION IN HETEROGENEOUS PHOTOCATALYSIS

Lopes, Osmando F.; Mendonça, Vagner R. de; Silva, Fernando B. F.; Paris, E. C.; Ribeiro, Cauê

doi:10.5935/0100-4042.20140280

Cited by 31 publications

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“…Semi-quantitative atomic compositions were evaluated by energy-dispersive X-ray (EDX) spectrometry using 45 a Thermo Noran device coupled to a SEM (Jeol JEM 2010).…”

Section: Powder Characterizationmentioning

confidence: 99%

“…Among them, the monoclinic phase shows better photocatalytic performance under visible radiation, probably due to the lower and suitable band gap of around 2.4 eV. [22][23][24] This low band gap value is a result of the hybridization 45 between the Bi 2s orbital and the O 2p orbital, which causes a shift in the valence band, and decreases the difference of energy between the valence and conduction bands. 20,25 Although monoclinic BiVO 4 phase has been well studied as a photocatalyst, its role on the mechanism involved in the photocatalysis process 50 is still open.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of BiVO₄via oxidant peroxo-method: insights into the photocatalytic performance and degradation mechanism of pollutants

et al. 2015

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This paper reports the synthesis of monoclinic bismuth vanadate (BiVO 4 ) by the oxidant peroxide method with crystallization under hydrothermal conditions, and its catalytic performance on the photodegradation of pollutants under visible-light. The as-synthesized BiVO 4 materials were characterized by means of XRD, EDX, Raman spectroscopy, UV-Vis DRS and FEG-SEM. The hydrothermal treatment above 80 °C 10 was required to obtain pure monoclinic BiVO 4 phase by releasing V 5+ ions from vanadium peroxo complexes. With the increase in hydrothermal reaction temperature, the particle size decreased. All BiVO 4 samples presented large size and shape distribution and band gap of approximately 2.40 eV. The as-prepared BiVO 4 catalysts showed high photoactivity for decomposition of model pollutants, methylene blue and rhodamine B dyes, under exposure to visible-light. The photodegradation mechanism was 15 evaluated by adding scavengers, DMSO and KBrO 3 , which were used to probe • OH radical and conduction band (CB) electrons, respectively. It was observed that photodegradation of MB and RhB dyes is caused by the action of • OH radicals, and that BiVO 4 CB electrons do not have reduction potential sufficiently high to reduce dissolved oxygen to O 2 -• . It was proven that the indirect mechanism, i.e. • OH radical formation, plays the major role on the BiVO 4 -assisted photodegradation process. 20

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“…Semi-quantitative atomic compositions were evaluated by energy-dispersive X-ray (EDX) spectrometry using 45 a Thermo Noran device coupled to a SEM (Jeol JEM 2010).…”

Section: Powder Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis of BiVO₄via oxidant peroxo-method: insights into the photocatalytic performance and degradation mechanism of pollutants

et al. 2015

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“…É também o maior produtor mundial da substância, representando mais de 90% do total mundial [2]. O nióbio possui uma importante e ampla aplicabilidade, por exemplo, nos setores de alta tecnologia, como em indústrias aeroespaciais com o desenvolvimento das superligas metálicas, aços microligados e aços inoxidáveis, supercondutores, microcapacitores entre outras formidáveis aplicações [3]. Outra aplicação que envolve este elemento é na produção de catalisadores químicos e também em lentes e vidros de alta performance, que, usualmente, têm sua performance melhorada devido ao aumento do índice de refração causado pelo óxido de nióbio [4].…”

Section: Introductionunclassified

Caracterização Elipsométrica De Nióbio Metálico

Nunes¹,

Garcia²,

Alves³

et al. 2017

Anais Do Congresso Anual Da ABM

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ResumoO presente trabalho tem como objetivo promover, através da técnica de elipsometria, a caracterização de propriedades ópticas e dielétricas do nióbio metálico e, além disto, medir a espessura dos filmes finos de óxido de nióbio formados. Devido a grande variedade de aplicações em importantes setores, o nióbio se tornou um elemento de grande importância para o desenvolvimento tecnológico em áreas estratégicas e o Brasil destaca-se neste contexto por deter as maiores reservas mundiais. Logo, conhecer o máximo de informações sobre este material é de grande importância para direcionar estudos às aplicações tecnológicas a fim de se agregar valor ao nióbio e seus compostos. Após a realização das medidas de parâmetros elipsométricos, e modelagem apropriadas, foram geradas satisfatoriamente as propriedades ópticas e dielétricas do material. Sendo também medida a espessura do óxido formado de forma natural sobre o substrato de nióbio metálico. Palavras-chave: Nióbio; Óxido de nióbio; Elipsometria. ELLIPSOMETRIC CHARACTERIZATION OF METALLIC NIOBIUM AbstractThis study aims to promote, through the ellipsometry technique, the characterization of metallic niobium optical and dielectric properties and, in addition, to measure the formed thin niobium oxide films thickness. Due to the wide variety of applications in important sectors, niobium has become an element of great significance to the technological development in strategic areas and Brazil stands out in this context by detaining the largest reserves. Therefore, to know as much information as possible about this material is of great importance to direct researches to technological applications in order to add value to the niobium and its compounds. After the achievement of ellipsometry measurements and modelling, it has been satisfactorily generated the optical properties of the material. And also measured the thickness of the naturally formed oxide on niobium metal substrate.

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“…Por ejemplo, Nb2O5 es muy usado en el sector aeroespacial, donde es utilizado en la fabricación de micro capacitores [1]; mientras que la alta estabilidad química, alto índice de refracción y bajo coeficiente de absorción, hacen que Ta2O5 pueda ser usado en la fabricación de capacitores de películas delgadas y en cubiertas anti reflectivas para celdas solares [2].…”

Section: Introductionunclassified

Propiedades piezoeléctricas del Pentóxido de Niobio y Pentóxido de Tantalio

Giraldo-Giraldo

Pérez-Walton

Osório-Guillén

2017

TecnoL.

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Nb2O5 y Ta2O5 son óxidos semiconductores de brecha ancha, los cuales en los últimos años han despertado gran interés debido a sus múltiples aplicaciones tecnológicas, ya sea en electrónica, telecomunicaciones o fotocatálisis. Por estas razones, en este trabajo presentamos un estudio a partir de cálculos de primeros principios de las propiedades piezoeléctricas de las fases Z y β de Ta2O5, y de las fases Z y P de Nb2O5 utilizado la teoría de los funcionales de la densidad y la aproximación del gradiente, generalizado con la parametrización PBEsol. Una vez determinada la geometría de equilibrio para cada una de estas fases, realizamos un cálculo utilizando respuesta lineal para determinar el tensor piezoeléctrico asociado a cada una de estas fases, encontrando que la fase Z para ambos compuestos presenta una buena respuesta piezoeléctrica. Adicionalmente, encontramos que la fase β-Ta2O5 no presenta respuesta piezoeléctrica.

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NIOBIUM OXIDES: AN OVERVIEW OF THE SYNTHESIS OF Nb₂O₅AND ITS APPLICATION IN HETEROGENEOUS PHOTOCATALYSIS

Cited by 31 publications

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Synthesis of BiVO₄via oxidant peroxo-method: insights into the photocatalytic performance and degradation mechanism of pollutants

Synthesis of BiVO₄via oxidant peroxo-method: insights into the photocatalytic performance and degradation mechanism of pollutants

Caracterização Elipsométrica De Nióbio Metálico

Propiedades piezoeléctricas del Pentóxido de Niobio y Pentóxido de Tantalio

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NIOBIUM OXIDES: AN OVERVIEW OF THE SYNTHESIS OF Nb2O5AND ITS APPLICATION IN HETEROGENEOUS PHOTOCATALYSIS

Cited by 31 publications

References 0 publications

Synthesis of BiVO4via oxidant peroxo-method: insights into the photocatalytic performance and degradation mechanism of pollutants

Synthesis of BiVO4via oxidant peroxo-method: insights into the photocatalytic performance and degradation mechanism of pollutants

Caracterização Elipsométrica De Nióbio Metálico

Propiedades piezoeléctricas del Pentóxido de Niobio y Pentóxido de Tantalio

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NIOBIUM OXIDES: AN OVERVIEW OF THE SYNTHESIS OF Nb₂O₅AND ITS APPLICATION IN HETEROGENEOUS PHOTOCATALYSIS

Synthesis of BiVO₄via oxidant peroxo-method: insights into the photocatalytic performance and degradation mechanism of pollutants

Synthesis of BiVO₄via oxidant peroxo-method: insights into the photocatalytic performance and degradation mechanism of pollutants