Página 1 dos resultados de 82 itens digitais encontrados em 0.014 segundos

‣ Fast and reliable analyses of sulphite in fruit juices using a supramolecular amperometric detector encompassing in flow gas diffusion unit

MARTINS, Paulo R.; POPOLIM, Welliton D.; NAGATO, Leticia A. F.; TAKEMOTO, Emy; ARAKI, Koiti; TOMA, Henrique E.; ANGNES, Lucio; PENTEADO, Marilene De V. C.
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
57.820312%
A new compact system encompassing in flow gas diffusion unit and a wall-jet amperometric FIA detector, coated with a supramolecular porphyrin film, was specially designed as an alternative to the time-consuming Monier-Williams method, allowing fast, reproducible and accurate analyses of free sulphite species in fruit juices. In fact, a linear response between 0.64 and 6.4 ppm of sodium sulphite. LOD = 0.043 ppm, relative standard deviation of +/- 1.5% (n = 10) and analytical frequency of 85 analyses/h were obtained utilising optimised conditions. That superior analytical performance allows the precise evaluation of the amount of free sulphite present in foods, providing an important comparison between the standard addition and the standard injection methods. Although the first one is most frequently used, it was strongly influenced by matrix effects because of the unexpected reactivity of sulphite ions with the juice matrixes, leading to its partial consumption soon after addition. In contrast, the last method was not susceptible to matrix effects yielding accurate results, being more reliable for analytical purposes. (C) 2011 Elsevier Ltd. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Instituto do Milenio de Materiais Complexos (IM2C); Instituto do Milenio de Materiais Complexos (IM2C)

‣ DESENVOLVIMENTO E AVALIAÇÃO DE ELETRODOS DE DIFUSÃO GASOSA (EDG) PARA GERAÇÃO DE H2O2 IN SITU E SUA APLICAÇÃO NA DEGRADAÇÃO DO CORANTE REATIVO AZUL 19; DEVELOPMENT AND EVALUATION OF GAS DIFFUSION ELECTRODES (GDE) FOR GENERATION OF H2O2 IN SITU AND THEIR APPLICATION IN THE DEGRADATION OF REACTIVE BLUE 19 DYE

Rocha, Robson S.; Reis, Rafael M.; Beati, Andre A. G. F.; Lanza, Marcos R. V.; Sotomayor, Maria Del Filar T.; Bertazzoli, Rodnei
Fonte: SOC BRASILEIRA QUIMICA; SÃO PAULO Publicador: SOC BRASILEIRA QUIMICA; SÃO PAULO
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
88.62683%
DEVELOPMENT AND EVALUATION OF GAS DIFFUSION ELECTRODES (GDE) FOR GENERATION OF H2O2 IN SITU AND THEIR APPLICATION IN THE DEGRADATION OF REACTIVE BLUE 19 DYE. This work reports the development of GDE for electrogeneration of H2O2 and their application in the degradation process of Reactive Blue 19 dye. GDE produced by carbon black with 20% polytetrafluoroethylene generated up to 500 mg L-1 of H2O2 through the electrolysis of acidic medium at -0.8 V vs Ag/AgCl. Reactive Blue 19 dye was degraded most efficiently with H2O2 electrogenerated in the presence of Fe(II) ions, leading to removal of 95% of the original color and 39% of TOC at -0.8 V vs Ag/AgCl.; FAPESP; FAPESP; CNPq; CNPq; CAPES; CAPES

‣ Estudo do comportamento eletroquímico de carbono Printex 6L modificado com 2-terc-butil-9,10-antraquinona e 2-etil-9,10-antraquinona para a eletrogeração de H2O2 em meio ácido; Study of the electrochemical behavior of carbon Printex 6L modified with 2-tert-butyl-9,10-anthraquinone and 2-ethyl-9,10-anthraquinone for electrogeneration of the H2O2 in acid medium

Valim, Ricardo Bertholo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/09/2012 Português
Relevância na Pesquisa
68.60698%
Neste trabalho foi estudado o comportamento eletroquímico de materiais à base de carbono Printex 6L, sem e com a adição de compostos orgânicos da classe das quinonas (2-terc-butil-9,10-antraquinona (TBA) e 2-etil-9,10-antraquinona (EA)) para a produção de peróxido de hidrogênio (H2O2) a partir da reação de redução do oxigênio gasoso (O2). Na primeira etapa, foi utilizada a técnica de microcamada porosa depositada sobre um eletrodo de disco/anel rotatório, sendo que a partir dos resultados obtidos foram confeccionados eletrodos de difusão gasosa (EDG) para a eletrogeração de H2O2. Os melhores resultados utilizando a microcamada porosa foram para os materiais com a adição dos modificadores, sendo que o material com 1,0% (m/m) de TBA na demonstrou ser o mais eficiente na geração de peróxido de hidrogênio, apresentando eficiência 20% maior comparado ao Printex 6L sem modificador. Com o eletrodo de difusão gasosa confeccionado com o composto orgânico escolhido, na melhor porcentagem de adição mássica de modificador, obteve-se a concentração de 301 mg L-1, sendo que com o eletrodo confeccionado com Printex 6L sem modificador obteve-se a concentração de 175 mg L-1, sob as mesmas condições experimentais. A eficiência cinética também apresentou os mesmos resultados quanto à eficiência dos materiais escolhidos...

‣ Estudo da degradação do trimetoprim e do sulfametoxazol utilizando peróxido de hidrogênio (H2O2) eletrogerado por eletrodos de difusão gasosa (EDG); Study of degradation of trimethoprim and sulfamethoxazole using hydrogen peroxide (H2O2) eletrogenerated by gas diffusion electrodes

Silva, Fernando Lindo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/02/2013 Português
Relevância na Pesquisa
88.44184%
Atualmente a classe dos antibióticos se destaca pelo grande consumo e também pelo risco à saúde quando administrado de forma equivocada, esse aumento deve-se ao destaque cada vez maior da indústria de produtos farmacêuticos. Outra questão a ser levantada é a contaminação do meio ambiente por essa classe substâncias, pois após o uso pelo ser humano ocorre a eliminação natural de parte da concentração administrada, assim sendo liberadas nos esgotos e, posteriormente, contaminando os corpos d'água, a fauna e flora local. Assim, foi proposto um métodos diferente para a degradação desses compostos, utilizando a eletrodos de difusão gasosa (EDG) capazes de gerar peróxido de hidrogênio in situ e em meio ácido, precursores dos radicais hidroxila, responsáveis pela degradação. Foram estudados EDG's não catalisados e catalisados, com diferentes porcentagens de ftalocianina de ferro II, com relação à quantidade de peróxido produzido, melhor potencial de produção e cinética do processo. Os resultados revelaram que a incorporação de 0,5% de Ft-Fe no eletrodo apresentou os melhores resultados. Esse eletrodo foi escolhido então para realizar as degradações dos antibióticos sulfametoxazol e trimetoprim. Na célula eletroquímica utilizou-se o processo Fenton...

‣ Degradation of dipyrone via advanced oxidation processes using a cerium nanostructured electrocatalyst material

Assumpção, M. H M T; Moraes, A.; De Souza, R. F B; Reis, R. M.; Rocha, R. S.; Gaubeur, I.; Calegaro, M. L.; Hammer, P.; Lanza, M. R V; Santos, M. C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 256-261
Português
Relevância na Pesquisa
58.175757%
This work studied the degradation of dipyrone, via electrochemical processes and via electro-Fenton reaction using a 4% CeO2/C gas diffusion electrode (GDE) prepared via modified polymeric precursor method. This material was used to electrochemically generate H2O2 through oxygen reduction. The mean crystallite sizes estimated by the Scherrer equation for 4% CeO2/C were 4 nm for CeO2-x (0 4 4) and 5 nm for CeO2 (1 1 1) while using transmission electron microscopy (TEM) the mean nanoparticle size was 5.4 nm. X-ray photoelectron spectroscopy (XPS) measurements revealed nearly equal concentrations of Ce(III) and Ce(IV) species on carbon, which contained high oxygenated acid species like CO and OCO. Electrochemical degradation using Vulcan XC 72R carbon showed that the dipyrone was not removed during the two hour electrolysis in all applied potentials by electro-degradation. Besides, when the Fenton process was employed the degradation was much similar when using cerium catalysts but the mineralization reaches just to 50% at -1.1 V. However, using the CeO2/C GDE, in 20 min all of the dipyrone was degraded with 26% mineralization at -1.3 V and when the Fenton process was employed, all of the dipyrone was removed after 5 min with 57% mineralization at -1.1 V. Relative to Vulcan XC72R...

‣ Eletrosíntese do metanol e etilenoglicol utilizando eletrodo de difusão de gás; Electrosynthesis of methanol and ethyleneglicol using gas diffusion electrode

Robson da Silva Rocha
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 18/05/2010 Português
Relevância na Pesquisa
68.986924%
O etilenoglicol é um composto orgânico com vasta aplicação em diversos setores da indústria química. Embora as aplicações mais conhecidas sejam como líquido anti-congelante ou na composição de fluídos hidráulicos, o maior consumo deste composto está na fabricação de resinas poliéster saturadas e insaturadas, além de poliuretanos. A produção de etilenoglicol, ou etano-1,2-diol, é feita a partir da reação do óxido de etileno, ou 1,2-epoxietano, com água na presença de um catalisador, como ácido sulfúrico diluído, na temperatura de 60 ºC, porém a síntese do óxido de etileno demanda 300 ºC e 20 atm para a reação alcançar elevados níveis de rendimento. Neste trabalho propõe-se uma alternativa para a obtenção convencional do óxido de etileno, que, no eletrólito aquoso, forma-se etilenoglicol. O processo de oxidação do gás etileno utilizou-se eletrodos de difusão gasosa (EDG). O EDG foi produzido por pressão e sinterização dos óxido de titânio e rutênio. Os eletrodos foram caracterizados física e eletroquimicamente. Os eletrodos de difusão gasosa de Ti/Ru e Ti/Ru/V2O5 foram testados preliminarmente utilizando o metano como gás de trabalho e os resultados mostraram que o EDG de óxidos metálicos possui a propriedade de oxidar o metano formando metanol...

‣ Modificação de eletrodos com óxido/hidróxido de níquel e acoplamento em sistema de difusão gasosa para a determinação de etanol em amostras de vinho de cana-de-açúcar; Modification of electrodes with nickel oxyhydroxide and coupling in gas diffusion system for ethanol determination on fermentation broths

Gabriela Furlan Giordano
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/02/2015 Português
Relevância na Pesquisa
68.088677%
Este trabalho teve como objetivo desenvolver um sistema eletroquímico capaz de detectar e quantificar etanol presente em amostras de vinho de cana-de-açúcar. Três métodos de modificação de eletrodo de níquel foram estudados visando à obtenção das espécies Ni(OH)2/NiOOH. Um dos métodos consistiu no condicionamento eletroquímico em NaOH, o outro, na oxidação química em persulfato de amônio e tratamento térmico e o terceiro, na deposição eletroquímica de Ni(OH)2 dopados com Co2+ e Cd2+, a partir de solução contendo os nitratos desses metais. Esse último apresentou resultados com maior repetibilidade de preparação e resposta. As técnicas SEM-FEG e XPS foram empregadas, a fim de caracterizar morfologicamente o Ni(OH)2 obtido e permitir determinações qualitativas e quantitativas sobre a composição química da superfície, respectivamente. Para a aplicação nas amostras empregou-se a técnica de extração por difusão gasosa através de uma membrana hidrofóbica. Assim, um módulo de extração foi construído no qual uma membrana de PTFE separou a solução de etanol - a ser analisada - de uma solução receptora de NaOH 100,0 mmol L-1, na qual o sistema eletroquímico foi acoplado. As condições aplicadas ao sistema foram otimizadas de modo a resultar em menores desvios das medidas analíticas. O vapor de etanol recolhido na solução de NaOH foi analisado utilizando o eletrodo de trabalho desenvolvido e foi possível monitorar soluções de etanol no intervalo 2...

‣ DEVELOPMENT AND EVALUATION OF GAS DIFFUSION ELECTRODES (GDE) FOR GENERATION OF H2O2 IN SITU AND THEIR APPLICATION IN THE DEGRADATION OF REACTIVE BLUE 19 DYE

Rocha, Robson S.; Reis, Rafael M.; Beati, Andre A. G. F.; Lanza, Marcos R. V.; Sotomayor, Maria Del Filar T.; Bertazzoli, Rodnei
Fonte: Soc Brasileira Quimica; Sao Paulo Publicador: Soc Brasileira Quimica; Sao Paulo
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
88.44184%
DEVELOPMENT AND EVALUATION OF GAS DIFFUSION ELECTRODES (GDE) FOR GENERATION OF H2O2 IN SITU AND THEIR APPLICATION IN THE DEGRADATION OF REACTIVE BLUE 19 DYE. This work reports the development of GDE for electrogeneration of H2O2 and their application in the degradation process of Reactive Blue 19 dye. GDE produced by carbon black with 20% polytetrafluoroethylene generated up to 500 mg L-1 of H2O2 through the electrolysis of acidic medium at -0.8 V vs Ag/AgCl. Reactive Blue 19 dye was degraded most efficiently with H2O2 electrogenerated in the presence of Fe(II) ions, leading to removal of 95% of the original color and 39% of TOC at -0.8 V vs Ag/AgCl.

‣ LaNiO3-based catalyst in gas diffusion electrodes: activity and stability for oxigen reactions

Silva, R. A.; Soares, C. O.; Carvalho, M. D.; Jorge, M. E. Melo; Gomes, A.; Rangel, C. M.; Pereira, M. I. da Silva
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2013 Português
Relevância na Pesquisa
79.08388%
Perovskite-type oxides are potential catalysts for next generation of regenerative fuel cells. In particular, LaNiO3 has been recognised as one of the most promising oxygen electrodes. In this work LaNiO3 perovskite-type oxides, prepared by a self-combustion method [1, 2], have been used for the preparation of porous gas-diffusion electrodes (GDE). Electrodes were prepared on Toray carbon paper (CP) substrates, consisting of a diffusion layer, a catalyst layer and a Nafion® layer. The gas diffusion layers were prepared using Vulcan XC-72R. The catalyst ink was prepared by suspending the material in isopropanol, stirring the mixture in an ultrasonic bath to thoroughly disperse it. Ink slurries were also pasted onto glassy carbon discs and used as working electrodes for full kinetic studies at potential domains for the oxygen reduction (ORR) and oxygen evolution (OER) reactions. A systematic study on the effect of the oxide loading (OL) on the electrodes surface area was done by cyclic voltammetry. It was found a quasi linear variation between the electrodes surface area and the oxide loading. Roughness values varying from 106±3 to 307±6 were obtained for OL between 1 and 5 mg cm-2 respectively. The results show that the peak current density increases with the increasing on oxide loading as shown in Fig. 1. Higher current densities for ORR were obtained for the electrodes prepared using LaNiO3-based perovskite with partial substitution of Ni by Cu. Stability studies of the GDEs...

‣ Stability of LaNiO3 gas diffusion oxygen electrodes

Silva, R. A.; Soares, C. O.; Carvalho, M. D.; Rangel, C. M.; Pereira, M. I. da Silva
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
88.81778%
In this work LaNiO3 perovskite-type oxide, prepared by a self-combustion method, was optimized for activity and stability as an anode material for water electrolysis. A full electrochemical study was conducted in order to kinetically characterize electrodes prepared using carbon paper as a base for porous gas-diffusion electrodes in alkaline media, regarding water oxidation and oxygen reduction reactions at room temperature. An electrode stability study was performed by potential cycling and at constant current density, using cyclic voltammetry and electrochemical impedance spectroscopy to check on stability after cycling with complementary scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) analysis of fresh and degraded electrodes. Comparison was made using nickel foam as a support for LaNiO3 deposition. Carbon instability in the potential region of interest contrasted with the lower contact resistance between the oxide and support of the Ni foam. Higher metal oxide loadings and dimensional stability were also possible.

‣ Enhanced bifunctional activity of LaNiO3-based gas diffusion electrodes for regenerative fuel cells

Silva, R. A.; Soares, C. O.; Carvalho, M. D.; Rangel, C. M.; Pereira, M. I. da Silva
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2013 Português
Relevância na Pesquisa
98.81778%
Perovskites are of great interest when searching replacements for precious metals as catalyst for bifunctional oxygen electrodes involving the oxygen evolution(OER) and oxygen reduction reaction (ORR) as is the case of regenerative fuel cells. In this work a full electrochemical study on the electrochemical properties of gas diffusion electrodes (GDEs) using LaNiO3-based catalysts, conducted in alkaline media, led to a study of cyclability and durability. The incorporation of GDEs in a low power electrolyzer/fuel cell prototype was also attempted. The stability of the electrodes was assessed by potential cycling and at constant current density with good results.

‣ Evaluation of gas diffusion electrodes as detectors in amperometric hydrogen sensors

Lizcano-Valbuena,W. H.; Perez,J.; Paganin,V. A.; Gonzalez,E. R.
Fonte: Fundação Editora da Universidade Estadual Paulista Júlio de Mesquita Filho - UNESP Publicador: Fundação Editora da Universidade Estadual Paulista Júlio de Mesquita Filho - UNESP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2005 Português
Relevância na Pesquisa
98.74066%
This work is directed to the study and evaluation of gas diffusion electrodes as detectors in hydrogen sensors. Electrochemical experiments were carried out with rotating disk electrodes with a thin porous coating of the catalyst as a previous step to select useful parameters for the sensor. An experimental arrangement made in the laboratory that simulates the sensor was found appropriate to detect volumetric hydrogen percentages above 0.25% in mixtures H2:N2. The system shows a linear response for volumetric percentages of hydrogen between 0.25 and 2 %.

‣ Effects of the operational conditions on the membrane and electrode properties of a polymer electrolyte fuel cell

Passos,Raimundo R.; Ticianelli,Edson A.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2002 Português
Relevância na Pesquisa
58.378394%
The effects of the operational conditions on the membrane and electrode properties on a polymer electrolyte fuel cell (PEFC) were investigated as a function of the cell and the gas humidifiers temperatures, the thickness of the membrane, the impregnation with phosphotungstic acid (PWA), and the variation of the Nafion and Teflon contents in the gas diffusion electrodes. An increase of the membrane resistance was observed when the PEFC is operated at temperatures equal or higher than those of the gas humidifiers, and this is more apparent for thicker electrolyte films. In the presence of PWA, the physicochemical properties of the membrane do not appreciably change with temperature. However, in this case, a lower humidification temperature affects the electrode performance. Changes on the Nafion loading in the electrodes do not lead to any significant effect in the electrode and membrane properties. For high Teflon contents there is a small lowering of the membrane conductivity.

‣ Effects of the modification of gas diffusion electrodes by organic redox catalysts for hydrogen peroxide electrosynthesis

Forti,Juliane C.; Venâncio,Cristiane E.; Lanza,Marcos R. V.; Bertazzoli,Rodnei
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 Português
Relevância na Pesquisa
99.1505%
This paper reports a comparative study of the electrochemical performance of in situ hydrogen peroxide electrogeneration on gas diffusion electrodes modified by organic redox catalysts 2-ethylanthraquinone, 2-terc-butylanthraquinone and azobenzene in medium of 0.1 mol L-1 H2SO4 plus 0.1 mol L-1 K2SO4, pH = 1. Hydrogen peroxide generation proved strongly dependent on the applied potential and on the concentration of added catalysts. Electrode modifications led to a significant increase in H2O2 yield (30%) reaching 850 mg L-1, and the overpotential for oxygen reduction shifted to less negative values (400 mV vs Ag/AgCl for electrodes modified by quinones and 300 mV vs Ag/AgCl for electrodes modified by azobenzene) compared to noncatalyzed gas diffusion electrodes, resulting in reduced energy consumption of 596.5 to 232.4 kWh kg-1. The results indicated that the best electrode for H2O2 electrogeneration is the gas diffusion electrode modified with 10% of 2-ethylanthraquinone, offering the best cost to benefit ratio.

‣ A microflow analyzer with an integrated gas diffusion unit

Fonseca,Alexandre; Silva,Janaína da C. B.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 Português
Relevância na Pesquisa
68.253823%
This work describes the development of a microflow analyzer with an integrated gas-diffusion unit. Deep ultraviolet photolithography was employed to engrave the channels (width of 500 µm and depth of 440 µm) on two plates of urethane-acrylate (UA) photoresist, and a polytetrafluoroethylene (PTFE) membrane was adapted between the structures designed for manipulation of donor and acceptor solutions. To perform the conductivity measurements, three pairs of electrodes (six copper wires with 0.5 mm diameter) were coupled into guiding channels, orthogonal to detection channel. The proposed microfluidic device presented a total internal volume of 48 µL and supported flow rates up to 1.0 mL min-1 without leakages or membrane damages. Analytical signals for the determination of bicarbonate in mineral waters provided a linear response (R² = 0.999) for the concentration range studied (20 to 80 mg L-1), a limit of detection (LOD) of 2.3 mg L-1 and a relative standard deviation (RSD) of 2.5% (n = 5). A similar performance was observed for the determination of ammonium in medicinal tablets (R² = 0,998 (10-40 mg L-1), LOD = 2.9 mg L-1 and RSD = 3.0% (n = 5)). The sampling rates for HCO3- and NH4+ procedures were 15 and 25 injections h-1, respectively. For both applications...

‣ Valorización electroquímica de CO2 usando un electrodo de difusión de gases cargado con Sn para obtener formiato en disolución acuosa en modo continuo; Electrochemical valorization of CO2 using Sn gas diffusion electrode to obtain formate in aqueous solution in continuous mode

Castillo Martín, Andrés del
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Dissertação de Mestrado
Português
Relevância na Pesquisa
68.088677%
The reduction of the CO2 emissions is necessary to mitigate climate change and for this purpose the valorization of CO2 by electrochemical reduction appears as one of the most interesting option because it allows the conversion of CO2 into industrially useful chemicals. The aim of this work is to study the influence of key variables on the performance of an experimental system for continuous electro-reduction of CO2 to formate with a gas diffusion electrode (GDE), which was made with particles of Sn suspended in a commercial Nafion solution and deposited on carbon paper. This study continues previous works in our research group on electrochemical valorization of CO2 to formate with Pb and Sn plates. A 23 factorial design of experiments at different levels of current density (‘‘j’’), electrolyte flow rate/electrode area ratio (‘‘Q/A ratio’’) and Sn load on the GDE, with the addition of a central point was followed in this paper. The faradaic efficiency and the rate of formate production were obtained to assess the performance. The general results show a similar trend to the plate electrodes on the variables” j” and “Q/A ratio”: an increase in the current density rises the formate rate, at the expense of lowering the efficiency...

‣ Deposition and diffusion of platinum nanoparticles in porous carbon assisted by plasma sputtering

Caillard, Amael; Brault, Pascal; Mathias, J; Charles, Christine; Boswell, Roderick
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
58.0728%
Catalytic nano-clusters of platinum are deposited by high density plasma sputtering into porous carbon gas diffusion layers for low temperature fuel cell electrodes. This plasma process leads to the deposition of catalyst onto the surface of the substrate

‣ Deposition and Diffusion of Platinum Nanoparticles in Porous Carbon Assisted by Plasma Sputtering

Caillard, A.; Brault, Pascal; Mathias, J; Charles, Christine; Boswell, Roderick; Sauvage, T
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
58.21887%
Catalytic nano-clusters of platinum are deposited by high density plasma sputtering into porous carbon gas diffusion layers for low temperature fuel cell electrodes. This plasma process leads to the deposition of catalyst onto the surface of the substrate and assists its diffusion in the carbon layer. In this work, we discuss the influence of the plasma parameters on this diffusion of platinum.

‣ Towards stable bifunctional oxygen electrodes and corrosion resistant gas diffusion layers for regenerative fuel cells

Silva, R. A.; Soares, C. O.; Carvalho, M. D.; Jorge, M. E. Melo; Gomes, A.; Pereira, M. I. da Silva; Rangel, C. M.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2013 Português
Relevância na Pesquisa
89.38684%
ABSTRACT: Regenerative fuel cells (RFCs) can provide very high energy storage at minimal weight in a dual mode system, by combining an electrolyzer and a fuel cell. Although RFCs are an appealing technology their development is still at an early stage. One key issue is the search for highly active electrocatalysts for both oxygen reduction and water oxidation. Presently, platinum is the best electrocatalyst for the oxygen reduction reaction (ORR), but has a poor oxygen evolution (OER) performance while metal oxides catalyze the OER but not the ORR. Yet, the search for the development of bi-functional oxygen electrodes is also associated to structurally stable gas diffusion layers - they must be capable of withstanding high potentials when cells are operated in the electrolyzer mode and in addition, mass transport limitations when used as a cathode in fuel cell mode. A novel approach is used in this work to tackle the issue, focussing on the development of stable gas diffusion electrodes for the oxygen reactions, having as a base high surface area LaNiO3. Previous work by the authors has optimised the synthesis of the mentioned perovskite-type oxide, prepared by a self-combustion method. The high electrochemical surface area and low porosity of the oxide has been indicated by electrochemical impedance spectroscopy (EIS) and BET measurements. A full characterization has been the subject of recent publications [1...

‣ Redox stability and bifunctionality of LaNiO3-based oxygen electrodes

Silva, R. A.; Soares, C. O.; Carvalho, M. D.; Jorge, M. E. Melo; Gomes, A.; Rangel, C. M.; Pereira, M. I. da Silva
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2013 Português
Relevância na Pesquisa
58.33496%
One key issue in the development of Regenerative fuel cells (RFCs) is the availability of cheap, highly active electrocatalysts for both oxygen reduction and water oxidation. Perovskite-type oxides, with the general formula ABO3, are potential catalysts for next generation of regenerative fuel cells. In particular, LaNiO3 has been recognised as one of the most promising oxygen electrodes. In this work LaNiO3 perovskite-type oxides, prepared by a self-combustion method [1, 2], have been simultaneously optimized for activity and stability as an anode and cathode material for water oxidation and oxygen reduction reaction (ORR), respectively. Extremely high surface area has been measured by BET analysis with matching electrochemical activity estimated by cyclic voltammetry and electrochemical impedance spectroscopy. A full electrochemical study has been conducted in order to kinetically characterize the prepared electrodes in alkaline media, using a Ni foam and carbon paper as support material for the electrodes. For LaNiO3 deposits on Ni foam, low contact resistance between the oxide and support, possibility of high metal oxide loadings and dimensional stability were accomplished with remarkable stability in the region of oxygen evolution. For LaNiO3 deposits on carbon paper...