Effect of Nb/C ratio in the morphological, structural, optical and photocatalytic properties of novel and inexpensive Nb2O5/carbon xerogel composites

Moraes, Nícolas Perciani de; Bacani, Rebeca; Silva, Maria Lúcia Caetano Pinto da; Campos, Tiago Moreira Bastos; Thim, Gilmar Patrocínio; Rodrigues, Liana Álvares

doi:10.1016/j.ceramint.2018.01.073

Cited by 40 publications

(18 citation statements)

References 29 publications

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“…Figure 6 displays the Raman spectra results of oxide films on Inconel 625. The characteristic peaks located at 485, 550, 695, 1380, and 1590 cm −1 indicated that the oxide film mainly consisted of NiO [ 44 ], NiCr 2 O 4 [ 44 ], Cr 2 O 3 , and Nb 2 O 5 [ 45 ]. After 300 hours of immersion, the oxide films were composed of NiO and Nb 2 O 5 .…”

Section: Resultsmentioning

confidence: 99%

Effect of Iron Ion on Corrosion Behavior of Inconel 625 in High-Temperature Water

et al. 2020

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The corrosion behavior of an ultralow iron nickel-based alloy Inconel 625 under high-temperature water has been evaluated. The results show that surface oxidation and pitting were the principal corrosion mechanisms of Inconel 625 during the initial immersion period. The surface layer of the oxide film is first Ni-enriched and then Fe-enriched as immersion time increases. The iron ions dissolved from the autoclave could lead to the formation of NiFe2O4 and have a great influence on the oxidation behavior of Inconel 625. The oxides nucleated by solid-state reactions with selective dissolution of Fe and Ni and then grew up through precipitation of cations from solution.

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Section: Resultsmentioning

confidence: 99%

Effect of Iron Ion on Corrosion Behavior of Inconel 625 in High-Temperature Water

et al. 2020

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“…On the other hand, deployment of inorganic semiconductors, such as SrNb 2 O 6 , ZnGeO 4 , HNb 3 O 8 , Fe 2 V 4 O 13 , and BiWO 6 , for photoinduced CO 2 reduction operation also encounters limitations emergent from their large band gaps and poor visible light collection. Moreover, absurd, non-porous structural characteristics of these semiconductors impose photocatalytic reactions to be carried on the external surface, resulting in bulk charge recombination [64][65][66]. This scenario significantly lessens the efficiency of the photocatalytic reduction process, and comparatively porous organic-inorganic frameworks are justified to pacify these setbacks [67][68][69].…”

Section: Introductionmentioning

confidence: 99%

Recent Innovation of Metal-Organic Frameworks for Carbon Dioxide Photocatalytic Reduction

2019

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The accumulation of carbon dioxide (CO2) pollutants in the atmosphere begets global warming, forcing us to face tangible catastrophes worldwide. Environmental affability, affordability, and efficient CO2 metamorphotic capacity are critical factors for photocatalysts; metal-organic frameworks (MOFs) are one of the best candidates. MOFs, as hybrid organic ligand and inorganic nodal metal with tailorable morphological texture and adaptable electronic structure, are contemporary artificial photocatalysts. The semiconducting nature and porous topology of MOFs, respectively, assists with photogenerated multi-exciton injection and adsorption of substrate proximate to void cavities, thereby converting CO2. The vitality of the employment of MOFs in CO2 photolytic reaction has emerged from the fact that they are not only an inherently eco-friendly weapon for pollutant extermination, but also a potential tool for alleviating foreseeable fuel crises. The excellent synergistic interaction between the central metal and organic linker allows decisive implementation for the design, integration, and application of the catalytic bundle. In this review, we presented recent MOF headway focusing on reports of the last three years, exhaustively categorized based on central metal-type, and novel discussion, from material preparation to photocatalytic, simulated performance recordings of respective as-synthesized materials. The selective CO2 reduction capacities into syngas or formate of standalone or composite MOFs with definite photocatalytic reaction conditions was considered and compared.

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“…A Equação 19 pode ser simplificada para representar o modelo de pseudo primeira ordem (Equação 20) (MORAES et al, 2018): Fonte: Próprio autor Para o processo de adsorção, os materiais sintetizados com uma menor massa de hidróxido de potássio apresentam os maiores valores de capacidade de adsorção. Isso se deve, provavelmente, ao maior tamanho de poros obtido, característico de géis produzidos em pHs mais baixos (REY-RAAP et al, 2016).…”

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“…O carbono pode melhorar a absorção de luz visível e promover a transferência efetiva de carga interfacial através da heterojunção ZnO/Xerogel de carbono para inibir a recombinação de transportadores de carga(MA et al, 2015;ZHAO et al, 2016).Contudo, para a degradação do bisfenol-A, os materiais XZnC 5.0 e XZnC 5.0 (EtOH) apresentaram atividade fotocatalítica inferior ao óxido de zinco puro. Isso pode ser explicado pela razão de óxido de zinco e carbono presente nesses materiais, de modo que uma quantidade excessiva de carbono na matriz do fotocatalisador pode suprimir a atividade fotocatalítica desse tipo de compósito(MORAES et al, 2018). Os demais materiais apresentaram atividade superior ao óxido de zinco puro.Para a degradação dos dois contaminantes estudados, os materiais com proporções intermediárias entre semicondutor e carbono (XZnC 3.0 e XZnC 3.0 (EtOH)) apresentaram as melhores capacidades de degradação, evidenciando a sinergia entre o óxido de zinco e a matriz carbonosa acoplada.A Figura 52 mostra um gráfico comparativo das degradações finais obtidas para cada material e contaminante.…”

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“…Essa redução pode permitir que a luz na região do visível seja utilizada para a excitação eletrônica do semicondutor(SCHIAVELLO, 1997). Os métodos mais comuns para este fim são: modificação do fotocatalisador por dopagem com metais, acoplamento entre semicondutores com energia de gap estreita, dopagem com não metais, obtenção de compósitos semicondutor-material carbonoso(MORAES et al, 2018;HOFFMANN et al, 1995).Preparação e evolução do sol: O sol é preparado pela dispersão dos precursores em um solvente e pela adição de um catalisador. Após a adição do catalisador na solução precursora, a reação entre os precursores é desencadeada.…”

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Fotocatálise heterogênea aplicada na degradação de poluentes orgânicos utilizando catalisador híbrido de óxido de zinco-xerogel de carbono

Moraes¹

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Fotocatálise heterogênea aplicada na degradação de poluentes orgânicos utilizando catalisador híbrido de óxido de zinco-xerogel de carbono Lorena 2019 0 Palavras-chave: Fotocatalíse. Óxido de zinco. Xerogel de carbono. Poluente orgânicos persistentes. 6 ABSTRACT MORAES, N. P. Heterogeneous photocatalysis applied to the degradation of organic pollutants using a zinc oxide-carbon xerogel hybrid catalyst. 2019. 125 p. Dissertation (MasterThe development of ZnO/Carbon xerogel hybrid photocatalysts was studied, in order to increase the quantum efficiency of the degradation process of persistent organic pollutants. Specifically, the preparation of the ZnO-carbon xerogel hybrid was studied, being this the most significant technological innovation of this project, considering that the catalytic effect of this hybrid was not studied in the literature. The use of carbon xerogel in the preparation of the semiconductor-carbonaceous material is justified by its excellent electrical conductivity, high surface area and porosity, the latter being easily manipulated by modifications in the synthesis parameters. The choice of tannin as the precursor of the xerogel aims at reducing costs and environmental impacts, adding value to the proposed technological innovation. The influence of the pH and route of synthesis were evaluated, as well as the influence of the calcination temperature on the properties of the materials. Diffuse reflectance spectroscopy was the technique used to determine the gap energy of the samples. The morphology, elemental analysis, crystalline and chemical structure of the materials were determined by scanning electron microscopy, dispersive energy spectrometry, X-ray diffractometry, infrared and Raman spectroscopy, respectively. The charge balance on the material surface was analyzed by the point of zero charge methodology (PZC). The photocatalytic action of the material was evaluated by the decomposition of 4-chlorophenol and bisphenol A, determined by UV-Visible spectroscopy. All materials have the hexagonal crystalline structure of zinc oxide (wurtzite). The materials without tannin in their composition also present the zinc hydroxychloride monohydrate phase. The X-ray diffractograms and bandgap values obtained confirm the incorporation of the carbon in the crystalline structure of the zinc oxide. The materials produced via the alcohol route have lower values of crystallite and particle size, as well as a higher content of graphite in their composition and larger surface area, while the materials produced in aqueous solution have lower values of gap energy. All the materials presented photocatalytic activity when subjected to visible and solar radiation, and the materials with intermediate proportions between carbon xerogel and zinc oxide were superior for the photodegradation process. The materials produced via alcohol route are superior to those produced in aqueous solution, as far as the photocatalysis process is concerned. The maximum values found for the degradation of 4-chlorophenol and bisphenol A w...

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Effect of Nb/C ratio in the morphological, structural, optical and photocatalytic properties of novel and inexpensive Nb2O5/carbon xerogel composites

Cited by 40 publications

References 29 publications

Effect of Iron Ion on Corrosion Behavior of Inconel 625 in High-Temperature Water

Effect of Iron Ion on Corrosion Behavior of Inconel 625 in High-Temperature Water

Recent Innovation of Metal-Organic Frameworks for Carbon Dioxide Photocatalytic Reduction

Fotocatálise heterogênea aplicada na degradação de poluentes orgânicos utilizando catalisador híbrido de óxido de zinco-xerogel de carbono

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