Navegação por autor "943"

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  • IPEN-DOC 26619

    NANDENHA, J. ; NAGAHAMA, I.H.F. ; YAMASHITA, J.Y. ; FONTES, E.H. ; AYOUB, J.M.S. ; SOUZA, R.F.B. de ; FONSECA, F.C. ; NETO, A.O. . Activation of methane on PdZn/C electrocatalysts in an acidic electrolyte at low temperatures. International Journal of Electrochemical Science, v. 14, n. 12, p. 10819-10834, 2019. DOI: 10.20964/2019.12.76

    Abstract: PdZn/C electrocatalysts were prepared by sodium borohydride utilized as reducing agent for activation methane in an acidic medium at room temperature and in a proton exchange membrane fuel cell (PEMFC) at 80°C. The materials prepared were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The diffractograms of the PdZn/C electrocatalysts showed only peaks associated with Pd face-centered cubic (fcc) structure. Cyclic voltammograms (CV) of all electrocatalysts after adsorption of methane shown an increment in current during the anodic scan, this effect was more pronounced for Pd(70)Zn(30)/C. In situ ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) experiments was not observed the formation of intermediates adsorbed for PdZn/C electrocatalysts, this behavior indicated that the methane oxidation occurs by parallel mechanisms. Polarization curves at 80°C in PEMFC show that Pd(90)Zn(10)/C has superior performance over the other electrocatalysts in methane oxidation.

    Palavras-Chave: methane; palladium; zinc; electrocatalysts; sodium compounds; borohydrides; reduction; oxidation; polarization; electrolytes; diagrams

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  • IPEN-DOC 26975

    SANTIAGO, ELISABETE I. ; MATOS, BRUNO R. ; DRESCH, MAURO A.; ISIDORO, ROBERTA A. ; FONSECA, FABIO C. . Advances on Nafion-based composites for high temperature proton exchange membrane fuel cells. In: BRAZIL MRS MEETING, 16th, September 10-14, 2017, Gramado, RS. Abstract... São Carlos, SP: Aptor Software, 2017. p. 55-55.

    Abstract: PEMFC (Proton exchange membrane fuel cell) is considered a promising and efficient hydrogen fuelled electrical power source. However, PEMFC faces several technical problems, such as sluggish electrode reaction kinetics involving the limiting rate of the oxygen reduction and alcohol oxidation reactions, and high resistance to ion transport that could be surpassed with increasing of the operation temperature. The main impediment for such a temperature increase is the water dependent performance of the state-of-the-art Nafion electrolyte. Above 80 ºC water starts to evaporate considerably and Nafion microdomains begin to shrink, disrupting its percolative structure, leading from a conductor to insulator transition. In this work, the incorporation in-situ or ex-situ of an inorganic phase with hydrophilic properties, such as TiO2 and SiO2, into Nafion membranes has been evaluated as an interesting alternative to produce stable electrolytes able to operate at higher temperatures (130o C). The physical-chemistry and electrochemical characterisation has shown that the inorganic particles located in both the nonionic and ionic regions of the ionomer have important contributions to enhanced thermal stability and water uptake. Such features resulted in significant improvements of the PEMFCs using composite electrolytes tested at high operating temperature and low relative humidity. In addition, remarkable enhancement on the DEFC (Direct Ethanol Fuel Cell) performance (122 mW cm‑2) has been obtained as a result of an increase of ethanol oxidation reaction rate promoted by the combination of enhanced catalyst activity and high temperature of operation using stable composite Nafion-SiO2 electrolytes.

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  • IPEN-DOC 27790

    DRESCH, MAURO A. ; MATOS, BRUNO R. ; GODOI, DENIS R.M.; LINARDI, MARCELO ; FONSECA, FABIO C. ; VILLULLAS, HEBE de las M.; SANTIAGO, ELISABETE I. . Advancing direct ethanol fuel cell operation at intermediate temperature by combining Nafion-hybrid electrolyte and well-alloyed PtSn/C electrocatalyst. International Journal of Hydrogen Energy, v. 46, n. 24, p. 13252-13264, 2021. DOI: 10.1016/j.ijhydene.2021.01.123

    Abstract: The advancement of direct ethanol fuel cell (DEFC) represents a real challenge to electrochemical science because ethanol changes significantly the triple phase boundary properties such as the redox reactions and the proton transport. Ethanol molecules promote poor fuel cell performance due to their slow oxidation rate, reduction of the proton transport due to high affinity of ethanol by the membrane, and due to mixed potential when the ethanol molecules reach the cathode by crossover. DEFC performance has been improved by advances in the membranes, e.g., low ethanol crossover polymer composites, or electrode materials, e.g., binary/ternary catalysts. Herein, high temperature (130 °C) DEFC tests were systematically investigated by using optimized electrode and electrolyte materials: Nafion-SiO2 hybrid electrolyte and well-alloyed PtSn/C electrocatalyst. By optimizing both the electrode and the electrolyte in conjunction, DEFCs operating at 130 °C exhibited a threefold increase on performance as compared to standard commercially available materials.

    Palavras-Chave: direct ethanol fuel cells; electrocatalysts; hybridization; electrolytes; nanocomposites

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  • IPEN-DOC 26122

    SILVA, PAULO M. ; ESPOSITO, VINCENZO; MARANI, DEBORA; FLORIO, DANIEL Z. de; FONSECA, FABIO C. . Ceria-based ceramic composites for high temperature thermochemical applications. In: BRAZILIAN MRS MEETING, 17th, September 16-20, 2018, Natal, RN. Abstract... São Carlos: Aptor Software, 2018. p. 989-989.

    Abstract: Among thermochemical conversion processes, the production of fuels such as H2 via solar thermochemical cycles is potentially more efficient and more economical than the use of electric energy to electrolyze water. The principle of solar thermochemical cycles is based on the remarkable properties of some oxides, which can be reduced and oxidized cyclically (redox cycles), i.e., releasing and absorbing oxygen under certain temperature (or pressure) regimes. These redox cycles can be efficiently used to convert H2O (or CO2) to H2 (CO). Thermochemical redox cycles avoid the problematic step of fuel / O2 separation and allow operation at more moderate temperatures (~ 1500 K) [1]. In this work, a new material concept for the separation of high temperature H2O based on porous ceramic composites composed of an ultra-high temperature ceramic phase (UHTC) and doped cerium oxide is proposed. UHTC usually exhibit extremely low mass diffusion rates and excellent thermomechanical properties for high temperature applications [2]. Gadolinium-doped ceria (CGO) presents unique processes at low oxygen partial pressure (pO2 < 10-12 atm) and high temperatures (T > 800 °C) such as faster mass diffusion, which are not observed in conventional sintering under ambient air conditions. In CGO/Al2O3 composites the resulting effects driven by such mass diffusion are low viscosity flows and high reactivity between phases, indicated by the formation of CeAlO3[3]. In this work, a comparison is made between sintering CGO/Al2O3 under ambient air and reducing condition, focusing on densification, viscosity and the evolution of the microstructure. The redox process of CGO/Al2O3 is investigated using dilatometry, microscopy, and electrochemical impedance spectroscopy. The preliminary results evidenced that new phases with remarkable microstructure can be obtained at reducing atmosphere depending on the temperature of reoxidation during cooling

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  • IPEN-DOC 26130

    ISIDORO, ROBERTA A. ; SANTOS, GABRIEL S. dos; FONSECA, FABIO C. . CoNi/C electrocatalysts for alkaline fuel cell. In: BRAZILIAN MRS MEETING, 17th, September 16-20, 2018, Natal, RN. Abstract... São Carlos: Aptor Software, 2018. p. 228-228.

    Abstract: Solid alkaline fuel cell (SAFC) has been studied as possible alternatives in the production of electricity for portable and stationary applications. The oxygen reduction reaction (ORR) is key electrochemical processes, because his low kinetics decreases system efficiency. The main progresses in the cathodic side have been related to the development and improvement of activity and stability. In this way, non precious material has been studied, in the last years. Cobalt oxides have been reported to exhibit good performance for ORR. However, cobalt bimetallic can be more eficient catalysts for ORR, especially for its bifunctional function. Some Ni-based electrocatalysts have shown relevant good results for ORR in four-electron pathway. Song et al. Showed, for example, that Ni addition into Ag-based electrocatalysts for ORR decreases the ORR overpotential, while an increasing in the limiting current density is observed. In this way, a bimetallic CoNi/ C was produced to be used as a cathode in alkaline fuel cell.

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  • IPEN-DOC 27975

    FONSECA, FABIO C. ; MACHADO, MARINA F.S. ; MORAES, LETICIA P.R. ; RODRIGUES, THENNER S. ; KABIR, AHSANUL; MARANI, DEBORA; VAN NONG, NGO; ESPOSITO, VINCENZO. Controlling the sintering of ceria by shape-controlled synthesis of nanoparticles. In: INTERNATIONAL CONFERENCE ON HIGH-PERFORMANCE CERAMICS, 11th, May 25-29, 2019, Kunming, China. Abstract... 2019.

    Abstract: The influence of surface energy of Gd-doped CeO2 nanometric crystals with different morphologies on mass diffusion mechanisms is studied. Depending on the starting morphology (nanocubes, nanorods, and random nanoparticles) extremely different microstructures, ranging from rapidly densified to thermodynamically stable porous structures. We investigate Gd-doped ceria (10% molar, GDC) both for its relevance in several chemical, environmental and energy technologies, and because the extensive knowledge on diffusion effects ruling this compound. We synthesized GDC as nanocubes (NC) and nanorods (NR) by a hydrothermal method whereas randomly oriented nanoparticles (RD) were obtained by co-precipitation. All samples were measured as single phase GDC powders with narrow nanoparticle size distributions. The high surface area NR exhibit lower green density as compared to NC. Dilatometric analyses revealed that NR have a pronounced linear retraction starting at low temperatures (~200°C) with maximum sintering activity at ~1100°C. High surface energy in NRs leads to a rapid rod to sphere transformation as well as to a rapid densification despite relatively low green density. On the other hand, the solid state diffusion in NCs is significantly inhibited, as confirmed by the highly porous microstructure of sintered samples. The results indicated the possibility of controlling microstructure of GDC by defining the shape of nanoparticles for different application in which dense or stable pores are required.

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  • IPEN-DOC 27779

    NEGRO, MIGUEL L.M. ; FERLAUTO, ANDRE S.; FONSECA, FABIO C. . A descarbonização pela eletroquímica e seu impacto para uma sociedade sustentável. ComCiência, v. Dossiê 223, 2021.

    Palavras-Chave: electrochemistry; decarbonization; sustainability; methane

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  • IPEN-DOC 28387

    PINGARO, MILLENA C. ; FONSECA, FABIO C. . Desenvolvimento de catalisadores "core-shell' para reação de reforma a vapor do etanol. In: PROGRAMA INSTITUCIONAL DE BOLSAS DE INICIAÇÃO CIENTÍFICA; SEMINÁRIO ANUAL PIBIC, 27.; SEMINÁRIO ANUAL PROBIC, 18.; SEMINÁRIO ANUAL PIBITI, 11, 6-7 de dezembro, 2021, Online. Resumo expandido... São Paulo, SP: IPEN-CNEN/SP, 2021. p. 94-95.

    Palavras-Chave: catalysis; hydrogen; ethanol; carbon

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  • IPEN-DOC 28525

    RODRIGUES, L.N. ; MACHADO, MARINA ; MORAES, L.P.R. ; THYSSEN, V.V. ; FONSECA, F.C. . Development of anode-supported solid oxide fuel cell by co-tape casting and co-sintering. ECS Transactions, v. 103, n. 1, p. 2245-2251, 2021. DOI: 10.1149/10301.2245ecst

    Abstract: Simple and cost-effective technologies to produce solid oxide fuel cells require control of microstructure, thickness, homogeneity, and reproducibility of the functional layers. The manufacturing of a solid oxide fuel cell (SOFC) involves significant ceramic processing challenges to obtain layers with controlled microstructure. Possibly the most common technique for large-scale production of SOFCs is tape casting. In this study, YSZ electrolyte and 60NiO/YSZ anode slurries were studied for the production of half-cells deposited by the sequential tape casting technique. A co-sintering procedure was developed for the half-cells and after cathode deposition the single cells were tested.

    Palavras-Chave: solid oxide fuel cells; anodes; casting; viscosity

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  • IPEN-DOC 26115

    TABUTI, FRANCISCO N. ; PEREIRA, VICTORIA B. ; PIAZZOLLA, FERNANDO ; FONSECA, FABIO C. . Development of ceria-based direct ethanol intermediate-temperature solid oxide fuel cell. In: BRAZILIAN MRS MEETING, 17th, September 16-20, 2018, Natal, RN. Abstract... São Carlos: Aptor Software, 2018. p. 142-142.

    Abstract: Solid oxide fuel cells (SOFCs) have several advantages over traditional energygenerating devices. A key property is the possibility of using various fuels such as natural gas and ethanol, which are strategic for Brazil. This study addresses two aspects that need to be improved in SOFC: (a) the high operating temperature of the cell that brings several problems for assembly and operation of a power system, and (b) the deactivation of the cell due to the deposition of carbon on the surface of the nickel anode when the cell is fed with carbon-containing fuels. The properties of ceria-based/Ni cermets both as the anode material and as the catalytic layer for bio-ethanol fueled SOFC with yttria-stablilized zirconia electrolyte were investigated. Ceria-based/Ni cermets were studied as the catalytic layer deposited onto the standard yttria-stabilized zirconia/Ni anode for direct ethanol SOFCs. Properties of both Zr- and Nb-doped (10 mol%) ceria / Ni (15 vol%) cermets were investigated as the catalytic layer in direct ethanol SOFCs. Electrolyte-supported fuel cells with doped-ceria /Ni catalytic layer were tested for ~100 hours under (dry) ethanol. Fuel cells using the different ceria/Ni cermets showed excellent stability on ethanol. The promising results obtained with ceria-based anodes for SOFC of ethanol motivated the development of ceriabased SOFCs. Thus, intermediate-temperature SOFCs using doped-ceria electrolytes have been tested at 600 °C using hydrogen. Preliminary results show that direct ethanol SOFC are promising devices for efficient energy conversion at intermediate temperatures.

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  • IPEN-DOC 26429

    SANTOS, MONIQUE C.L. ; NUNES, LIVIA C. ; SILVA, LUIS M.G. ; RAMOS, ANDREZZA S. ; FONSECA, FABIO C. ; SOUZA, RODRIGO F.B. de ; NETO, ALMIR O. . Direct Alkaline Anion Exchange Membrane Fuel Cell to converting methane into methanol. ChemistrySelect, v. 4, n. 39, p. 11430-11434, 2019. DOI: 10.1002/slct.201902421

    Abstract: Methane is the main constituent of natural gas and can be converted in higher value-added products for electricity cogeneration. It could be used as a solid membrane reactor (SMR) for application in Alkaline Anion-Exchange Membrane Fuel Cell (AAEMFC). The investigation for the conversion of methane was based on sodium borohydride (NaBH4) method using Pt/C Basf, Pd/C, Ni/C as catalysts. The electrocatalysts were prepared with 20 wt% of metals loading on carbon. The X-ray diffraction (XRD) analysis revealed a face-centered cubic structure (FCC) for Pt/C and Pd/C catalysts, was observed Ni/ NiO phases for Ni/C electrocatalyst. The Transmission Electron Microscopy (TEM) exhibited a good dispersion of nanoparticles and some agglomerations on the support, with a mean size of 6.4 nm for Pd/C, 5.7 nm for Ni/C and near to 2 nm size for Pt/C. The experiments with AAEMFC showed that all materials can carry out the reaction spontaneously. Pt/C catalyst presents energy density higher than the other materials. FTIR data suggest that methane was converted into small products organic molecules such as methanol and formate in different potentials for Pt/C, Pd/C, and Ni/C. The products were quantified by Raman spectroscopy. The high conversion efficiency obtained was about 20% at 0.3 V using Pt/C catalyst, the maximum conversion over Pd/C was 17.5% at 0.15 V, associated with the formation of a thin layer of PdO on the catalytic surface. The highest conversion rate (13%) was observed in closed circuit potentials to the short circuit in the cell with Ni/C catalyst. The results suggest that for the selective conversion of methane to methanol are most promising using materials containing Pt or Pd.

    Palavras-Chave: methane; fuel cells; methanol; spectroscopy; electrocatalysts; catalysts; natural gas; raman spectroscopy; transmission electron microscopy

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  • IPEN-DOC 26698

    SANTOS, MONIQUE C.L. ; NUNES, LIVIA C. ; SILVA, LUIS M.G. ; RAMOS, ANDREZZA S. ; FONSECA, FABIO C. ; SOUZA, RODRIGO F.B. de ; NETO, ALMIR O. . Direct Alkaline Anion-Exchange Membrane Fuel Cell to converting methane into methanol. In: ENERGY TRANSITION RESEARCH AND INNOVATION, October 1-2, 2019, São Paulo, SP. Abstract... São Paulo: Research Centre for Gas Innovation, 2019.

    Abstract: Methane is the main constituent of natural gas and can be converted in energy with fuel cell application and higher value-added chemicals cogeneration. In Alkaline Anion-Exchange Membrane Fuel Cell (AAEMFC) is possible led in a way that leads to more oxidized products, therefore more electrons transferred. The investigation was realized for the methane oxidation on Pt/C, Pd/C, Ni/C as catalysts. The electrocatalysts were prepared using a sodium borohydride method with 20 wt% of metals loading on carbon. The X-ray diffraction (XRD) analysis revealed a cubic face-centred structure (CFC) for Pt/C and Pd/C catalysts, was observed Ni/NiO phases for Ni/C electrocatalyst. The Transmission Electron Microscopy (TEM) exhibited a good dispersion of nanoparticles and some agglomerations on the support, with a mean size of 6.4 nm for Pd/C, 5.7 nm for Ni/C and near to 2 nm size for Pt/C. The experiments with AAEMFC showed that all materials can carry out the reaction spontaneously. Pt/C catalyst presents energy density twice times higher than the other materials. FTIR data suggest that methane was converted into small products organic molecules such as methanol and formate in different potentials for Pt/C, Pd/C, and Ni/C.

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  • IPEN-DOC 28661

    THYSSEN, VIVIAN V. ; VILELA, VANESSA B. ; FLORIO, DANIEL Z. de; FERLAUTO, ANDRE S.; FONSECA, FABIO C. . Direct conversion of methane to C2 hydrocarbons in solid-state membrane reactors at high temperatures. Chemical Reviews, v. 122, n. 3, p. 3966-3995, 2022. DOI: 10.1021/acs.chemrev.1c00447

    Abstract: Direct conversion of methane to C2 compounds by oxidative and nonoxidative coupling reactions has been intensively studied in the past four decades; however, because these reactions have intrinsic severe thermodynamic constraints, they have not become viable industrially. Recently, with the increasing availability of inexpensive “green electrons” coming from renewable sources, electrochemical technologies are gaining momentum for reactions that have been challenging for more conventional catalysis. Using solid-state membranes to control the reacting species and separate products in a single step is a crucial advantage. Devices using ionic or mixed ionic−electronic conductors can be explored for methane coupling reactions with great potential to increase selectivity. Although these technologies are still in the early scaling stages, they offer a sustainable path for the utilization of methane and benefit from the advances in both solid oxide fuel cells and electrolyzers. This review identifies promising developments for solid-state methane conversion reactors by assessing multifunctional layers with microstructural control; combining solid electrolytes (proton and oxygen ion conductors) with active and selective electrodes/catalysts; applying more efficient reactor designs; understanding the reaction/degradation mechanisms; defining standards for performance evaluation; and carrying techno-economic analysis.

    Palavras-Chave: hydrocarbons; solid-state plasma; natural gas; coupling; oxidation; electrochemistry

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  • IPEN-DOC 26968

    MATOS, B.R. ; SANTIAGO, E.I. ; TOSCO, B.; REY, J.F.Q.; SILVA, J.S. da ; SCHADE, U.; PUSKAR, L.; AZIZ, E.F.; FONSECA, F.C. . Efeito da relaxação do polímero na cristalinidade, fase iônica e formação de grupos sulfônicos anidridos no Nafion / Effect of the polymer relaxation on the crystallinity, ionic phase and sulfonic anhydrides formation of Nafion. In: SIMPÓSIO BRASILEIRO DE ELETROQUÍMICA E ELETROANALÍTICA, 21., 17-21 de abril, 2017, Natal, RN. Resumo... Campinas, SP: Galoá, 2017.

    Abstract: A relação entre as propriedades estruturais e elétricas de amostras de Nafion preparadas sob tratamento térmico em diferentes temperaturas (220 > T > 100 °C) foi investigada por espectroscopia no infravermelho (FTIR), espalhamento de raios-X em baixo ângulo (SAXS), calorimetria diferencial exploratória (DSC), análise dinâmico-mecânica (DMA) e espectroscopia de impedância (IS). Os resultados combinados de FTIR, SAXS, DSC, DMA revelaram que o tratamento térmico em baixas umidades relativas altera a morfologia do Nafion irreversivelmente devido a três características principais: i) o rearranjo das ligações de hidrogênio; ii) o reordenamento da fase cristalina; e iii) a formação de grupos sulfônicos anidridos. No entanto, a formação dos grupos anidridos é revertida pela reacidificação da membrana em soluções ácidas. O aspecto mais importante da dinâmica dos três processos descritos é que tais alterações são aceleradas acima de uma temperatura crítica: a temperatura de término da transição α do Nafion (Tendα ~ 160 °C). A transição α é atribuída ao enfraquecimento das interações eletrostáticas existentes entre os grupos sulfônicos do Nafion, que permitem a movimentação de longo alcance das cadeias poliméricas [1]. Este resultado indica que a maior dinâmica das cadeias do polímero em T > Tendα é o principal fator envolvido na modificação irreversível da morfologia do Nafion. As alterações da estrutura das ligações de hidrogênio afetaram negativamente as propriedades elétricas do Nafion. O aumento da temperatura de tratamento térmico reduz a condutividade protônica e aumenta a energia de ativação do transporte de cargas no Nafion. Tais resultados são relevantes para a preparação de conjuntos eletrodos-membrana (MEA) e para a operação de células a combustível de eletrólito polimérico (PEFC) em altas temperaturas [1].

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  • IPEN-DOC 29759

    BARBOSA, ANDREY S. ; BIANCOLLI, ANA L.G. ; LANFREDI, ALEXANDRE J.C.; RODRIGUES JR., ORLANDO ; FONSECA, FABIO ; SANTIAGO, ELISABETE I. . Effects of irradiation conditions on LDPE-Based anion exchange membranes properties—performance and stability. In: YILDIZ, BILGE (Org.) INTERNATIONAL CONFERENCE ON SOLID STATE IONICS, 23rd, July 17-22, 2022, Boston, MA. Abstract... 2022.

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  • IPEN-DOC 29760

    OLIVEIRA, RAPHAEL A.M.P. de; FERLAUTO, ANDRE S.; TRINDADE, FABIANE D.; FLORIO, DANIEL Z.; FONSECA, FABIO . Effects of La Content in Ceria-Lanthana thin films prepared by pulsed laser deposition. In: YILDIZ, BILGE (Org.) INTERNATIONAL CONFERENCE ON SOLID STATE IONICS, 23rd, July 17-22, 2022, Boston, MA. Abstract... 2022.

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  • IPEN-DOC 30151

    OLIVEIRA, RAPHAEL A.M.P. de; TRINDADE, FABIANE J.; FLORIO, DANIEL Z. de; FONSECA, FABIO C. ; ESPOSITO, VINCENZO; FERLAUTO, ANDRE S.. Effects of La content in ceria-lanthana thin films prepared by pulsed laser deposition. In: BRAZIL MRS MEETING, 21st, October 1-5, 2023, Maceió, AL. Abstract... São Carlos, SP: Aptor Software, 2023. p. 810-810.

    Abstract: Solid oxide electrochemical reactors are a promising alternative for challenging chemical reactions, such as oxidative coupling of methane (OCM)[1], which convert methane to C2+products. Cerium oxide is a commonly studied oxide membrane material for its high ionic conductivity in the temperature range ideal for conversion reactions (600-900°C), particularly when doped with rare earth cations like Gd, Sm, or La. Recent studies have shown La2Ce2O7as a promising OCM catalyst[2]. This study investigates the structural properties of LaxCe(1-x)O2(1-x/2)thin films, prepared using pulsed laser deposition, with varying stoichiometry. XRD results indicate textured film growth with preferential [100] orientation of cubic crystalline fluorite for low La content (x≤0.5), while x>0.5 had a random orientation. La doping expanded the fluorite structure, increasing lattice parameters from 5.42 Å for x=0 to 5.69 Å for x=0.7. UV-Raman spectroscopy showed that La content x=10 caused a more pronounced balance between Ce4+and Ce3+than pure ceria samples. Impedance revealed a direct relationship between La content and resistance, indicating lower resistance with lower La content. These findings could lead to using Ce-La oxides thin films as catalysts for OCM in electrochemical reactors based on ceria.

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  • IPEN-DOC 28499

    MUCCILLO, REGINALDO ; FLORIO, DANIEL Z. de; FONSECA, FABIO C. ; CARVALHO, SABRINA G.M. ; MUCCILLO, ELIANA N.S. . Electric field-assisted sintering anode-supported single solid oxide fuel cell. International Journal of Applied Ceramic Technology, v. 19, n. 2, p. 906-912, 2022. DOI: 10.1111/ijac.13871

    Abstract: Cosintering (La0.84Sr0.16MnO3 thin-film cathode/ZrO2: 8 mol% Y2O3 thin-film solid electrolyte/55 vol.% ZrO2:8 mol% Y2O3 + 45 vol.% NiO anode, ϕ = 12 × 1.5 mm thick pellet) was achieved by applying an electric field for 5 min at 1200°C. Impedance spectroscopy measurements of the anode-supported three-layer cell show an improvement of the electrical conductivity in comparison to that of a conventionally sintered cell. The scanning electron microscopy images of the cross-sections of electric field-assisted pressureless sintered cells show a fairly dense electrolyte and porous anode and cathode. Joule heating, resulting from the electric current due to the application of the AC electric field, is suggested as responsible for sintering. Dilatometric shrinkage curves, electric voltage and current profiles, impedance spectroscopy diagrams, and scanning electron microscopy micrographs show how anode-electrolyte-cathode ceramic cells can be cosintered at temperatures lower than the usually required.

    Palavras-Chave: solid oxide fuel cells; dilatometry; electric fields; electric impedance; sintering

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  • IPEN-DOC 26699

    NANDENHA, JULIO ; YAMASHITA, JESSICA Y. ; FONTES, ERIC H. ; FONSECA, FABIO C. ; NETO, ALMIR O. . Electrocatalytic oxidation of methane in an acidic electrolyte using PdMn/C-ITO electrocatalysts synthetized by sodium borohydride reduction process. In: ENERGY TRANSITION RESEARCH AND INNOVATION, October 1-2, 2019, São Paulo, SP. Abstract... São Paulo: Research Centre for Gas Innovation, 2019.

    Abstract: Pd/C-ITO and PdMn/C-ITO electrocatalysts with different atomic ratio (90:10, 70:30 and 50:50) were synthetized by borohydride reduction method and characterized by X-ray diffraction, Transmission electronic microscopy and electrochemical studies (cyclic voltammetry). The electrochemical studies showed that PdMn(50:50)/C-ITO had superior performance for electrochemical oxidation of methane in an acidic electrolyte at 25 oC compared to others electrocatalysts prepared. The experiments in a single DMEFC also showed that the PdMn(70:30)/C-ITO electrocatalyst exhibited higher performance for methane oxidation in comparison with Pd/C-ITO, PdMn(90:10)/C-ITO and PdMn(50:50)/C-ITO electrocatalysts. These result indicated that the addition of Mn to Pd favor the electrochemical oxidation of Methane in acid medium, where this effect could be attributed to the synergy between the constituents of the binary electrocatalysts or to electronic modification of Pd atoms by the neighboring Mn atoms as the proximity of Pd and Mn atoms on the surface of the C-ITO (bifunctional mechanism - the presence of Pd and Mn oxides species).

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  • IPEN-DOC 29860

    MACHADO, MARINA ; BAIUTTI, F.; BERNADET, L.; MORATA, A.; NUNEZ, M.; OUWELTJES, J.P.; FONSECA, F.C. ; TORRELL, M.; TARANCON, A.. Engineered nanofunctional thin films as interfacial layers to enhance performance and durability of SOFCs. ECS Transactions, v. 111, n. 6, p. 1453-1462, 2023. DOI: 10.1149/11106.1453ecst

    Abstract: A strategy to improve the performance and durability of solid oxide fuel cells (SOFCs) is to increase the cathodic activity and decrease the interfacial resistance between the cathode and electrolyte. Pulsed laser deposition (PLD) has been shown to be a promising method to engineer functional interlayers to enhance the cell's performance. In the present study, a bilayer consisting of Sm0.2Ce0.8O2−δ (SDC) barrier layer (BL) and a nanocomposite consisting of SDCLa0.8Sr0.2MnO3−δ (SDC-LSM) employed as a cathode functional layer were deposited by PLD in an anode supported SOFC. The fuel cell showed maximum power density of 0.30 W∙cm−2 at 750 °C. Most importantly, a durability test carried out for 700 h at 750 °C showed a remarkably stable performance of the fuel cell.

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✔ É possível efetuar a busca de um autor ou um termo em todo o RD, por meio do Buscar no Repositório , isto é, o termo solicitado será localizado em qualquer campo do RD. No entanto esse tipo de pesquisa não é recomendada a não ser que se deseje um resultado amplo e generalizado.

✔ A pesquisa apresentará melhor resultado selecionando um dos filtros disponíveis em Navegar

✔ Os filtros disponíveis em Navegar tais como: Coleções, Ano de publicação, Títulos, Assuntos, Autores, Revista, Tipo de publicação são autoexplicativos. O filtro, Autores IPEN apresenta uma relação com os autores vinculados ao IPEN; o ID Autor IPEN diz respeito ao número único de identificação de cada autor constante no RD e sob o qual estão agrupados todos os seus trabalhos independente das variáveis do seu nome; Tipo de acesso diz respeito à acessibilidade do documento, isto é , sujeito as leis de direitos autorais, ID RT apresenta a relação dos relatórios técnicos, restritos para consulta das comunidades indicadas.

A opção Busca avançada utiliza os conectores da lógica boleana, é o melhor recurso para combinar chaves de busca e obter documentos relevantes à sua pesquisa, utilize os filtros apresentados na caixa de seleção para refinar o resultado de busca. Pode-se adicionar vários filtros a uma mesma busca.

Exemplo:

Buscar os artigos apresentados em um evento internacional de 2015, sobre loss of coolant, do autor Maprelian.

Autor: Maprelian

Título: loss of coolant

Tipo de publicação: Texto completo de evento

Ano de publicação: 2015

✔ Para indexação dos documentos é utilizado o Thesaurus do INIS, especializado na área nuclear e utilizado em todos os países membros da International Atomic Energy Agency – IAEA , por esse motivo, utilize os termos de busca de assunto em inglês; isto não exclui a busca livre por palavras, apenas o resultado pode não ser tão relevante ou pertinente.

✔ 95% do RD apresenta o texto completo do documento com livre acesso, para aqueles que apresentam o significa que e o documento está sujeito as leis de direitos autorais, solicita-se nesses casos contatar a Biblioteca do IPEN, bibl@ipen.br .

✔ Ao efetuar a busca por um autor o RD apresentará uma relação de todos os trabalhos depositados no RD. No lado direito da tela são apresentados os coautores com o número de trabalhos produzidos em conjunto bem como os assuntos abordados e os respectivos anos de publicação agrupados.

✔ O RD disponibiliza um quadro estatístico de produtividade, onde é possível visualizar o número dos trabalhos agrupados por tipo de coleção, a medida que estão sendo depositados no RD.

✔ Na página inicial nas referências são sinalizados todos os autores IPEN, ao clicar nesse símbolo será aberta uma nova página correspondente à aquele autor – trata-se da página do pesquisador.

✔ Na página do pesquisador, é possível verificar, as variações do nome, a relação de todos os trabalhos com texto completo bem como um quadro resumo numérico; há links para o Currículo Lattes e o Google Acadêmico ( quando esse for informado).

ATENÇÃO!

ESTE TEXTO "AJUDA" ESTÁ SUJEITO A ATUALIZAÇÕES CONSTANTES, A MEDIDA QUE NOVAS FUNCIONALIDADES E RECURSOS DE BUSCA FOREM SENDO DESENVOLVIDOS PELAS EQUIPES DA BIBLIOTECA E DA INFORMÁTICA.

O gerenciamento do Repositório está a cargo da Biblioteca do IPEN. Constam neste RI, até o presente momento 20.950 itens que tanto podem ser artigos de periódicos ou de eventos nacionais e internacionais, dissertações e teses, livros, capítulo de livros e relatórios técnicos. Para participar do RI-IPEN é necessário que pelo menos um dos autores tenha vínculo acadêmico ou funcional com o Instituto. Nesta primeira etapa de funcionamento do RI, a coleta das publicações é realizada periodicamente pela equipe da Biblioteca do IPEN, extraindo os dados das bases internacionais tais como a Web of Science, Scopus, INIS, SciElo além de verificar o Currículo Lattes. O RI-IPEN apresenta também um aspecto inovador no seu funcionamento. Por meio de metadados específicos ele está vinculado ao sistema de gerenciamento das atividades do Plano Diretor anual do IPEN (SIGEPI). Com o objetivo de fornecer dados numéricos para a elaboração dos indicadores da Produção Cientifica Institucional, disponibiliza uma tabela estatística registrando em tempo real a inserção de novos itens. Foi criado um metadado que contém um número único para cada integrante da comunidade científica do IPEN. Esse metadado se transformou em um filtro que ao ser acionado apresenta todos os trabalhos de um determinado autor independente das variáveis na forma de citação do seu nome.

A elaboração do projeto do RI do IPEN foi iniciado em novembro de 2013, colocado em operação interna em julho de 2014 e disponibilizado na Internet em junho de 2015. Utiliza o software livre Dspace, desenvolvido pelo Massachusetts Institute of Technology (MIT). Para descrição dos metadados adota o padrão Dublin Core. É compatível com o Protocolo de Arquivos Abertos (OAI) permitindo interoperabilidade com repositórios de âmbito nacional e internacional.

1. Portaria IPEN-CNEN/SP nº 387, que estabeleceu os princípios que nortearam a criação do RDI, clique aqui.


2. A experiência do Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP) na criação de um Repositório Digital Institucional – RDI, clique aqui.

O Repositório Digital do IPEN é um equipamento institucional de acesso aberto, criado com o objetivo de reunir, preservar, disponibilizar e conferir maior visibilidade à Produção Científica publicada pelo Instituto, desde sua criação em 1956.

Operando, inicialmente como uma base de dados referencial o Repositório foi disponibilizado na atual plataforma, em junho de 2015. No Repositório está disponível o acesso ao conteúdo digital de artigos de periódicos, eventos, nacionais e internacionais, livros, capítulos, dissertações, teses e relatórios técnicos.

A elaboração do projeto do RI do IPEN foi iniciado em novembro de 2013, colocado em operação interna em julho de 2014 e disponibilizado na Internet em junho de 2015. Utiliza o software livre Dspace, desenvolvido pelo Massachusetts Institute of Technology (MIT). Para descrição dos metadados adota o padrão Dublin Core. É compatível com o Protocolo de Arquivos Abertos (OAI) permitindo interoperabilidade com repositórios de âmbito nacional e internacional.

O gerenciamento do Repositório está a cargo da Biblioteca do IPEN. Constam neste RI, até o presente momento 20.950 itens que tanto podem ser artigos de periódicos ou de eventos nacionais e internacionais, dissertações e teses, livros, capítulo de livros e relatórios técnicos. Para participar do RI-IPEN é necessário que pelo menos um dos autores tenha vínculo acadêmico ou funcional com o Instituto. Nesta primeira etapa de funcionamento do RI, a coleta das publicações é realizada periodicamente pela equipe da Biblioteca do IPEN, extraindo os dados das bases internacionais tais como a Web of Science, Scopus, INIS, SciElo além de verificar o Currículo Lattes. O RI-IPEN apresenta também um aspecto inovador no seu funcionamento. Por meio de metadados específicos ele está vinculado ao sistema de gerenciamento das atividades do Plano Diretor anual do IPEN (SIGEPI). Com o objetivo de fornecer dados numéricos para a elaboração dos indicadores da Produção Cientifica Institucional, disponibiliza uma tabela estatística registrando em tempo real a inserção de novos itens. Foi criado um metadado que contém um número único para cada integrante da comunidade científica do IPEN. Esse metadado se transformou em um filtro que ao ser acionado apresenta todos os trabalhos de um determinado autor independente das variáveis na forma de citação do seu nome.