RAFAEL NOGUEIRA BONIFÁCIO
4 resultados
Resultados de Busca
Agora exibindo 1 - 4 de 4
Artigo IPEN-doc 20117 Influence of the relative volumes between catalyst and nafion ionomer in the catalyst layer efficiency2014 - BONIFACIO, RAFAEL N.; OLIVEIRA NETO, ALMIR; LINARDI, MARCELOOver the years, studies have analyzed the composition of the catalyst layer using commercial platinum catalyst, supported on Vulcan XC72 with 20% of metal loading (Pt/C 20%Mw), and found that values between 20 and 40% of Nafion ionomer related to the mass of the catalyst layer (% NIW) have resulted in more efficient electrodes for PEMFC. Recent studies with catalysts synthesized on Vulcan XC72 resulted in 59% NIW as the best formulation. In this work, the commercial and the synthesized Pt/C 20%Mw catalyst were evaluated by Gas Pycnometry, Gas Adsorption (through BET and BJH), and Mercury Intrusion Porosimetry. The results showed volumetric differences between the Vulcan XC72 used in commercial catalyst and the Vulcan XC72 commercially available for synthesis (as purchased). These differences impair the synthesized catalyst in comparison with the commercial one. Therefore, the relationship between the quantities of catalysts and Nafion ionomer on the catalyst layers must be calculated as a function of the catalysts volumes.Artigo IPEN-doc 17219 Desenvolvimento de processo de produção de conjuntos eletrodo-membrana-eletrodo para células a combustível baseadas no uso de membrana polimérica condutora de prótons (PEMFC) por impressão a tela2011 - BONIFACIO, RAFAEL N.; LINARDI, MARCELO; CUENCA, RICARDOArtigo IPEN-doc 18815 Desenvolvimento de tecnologia para confecção de eletrodos e conjuntos eletrodo-membrana-eletrodo (MEA) por impressão à tela para aplicação em modulos de potência de células PEMFC2012 - FERNANDES, VALERIA C.; CUNHA, EDGAR F. da; BONIFACIO, RAFAEL N.; DRESCH, MAURO A.; DOUBEK, GUSTAVO; SANTIAGO, ELISABETE I.; LINARDI, MARCELOArtigo IPEN-doc 19047 Current density maximization in palladium-based gas diffusion electrode in proton exchange membrane fuel cell2013 - BONIFACIO, RAFAEL N.; OLIVEIRA NETO, ALMIR; LINARDI, MARCELOIn this study the influence of polymeric ionomer concentration on the performance of gas diffusion electrode containing Pd/C as a substitute for usual Pt/C electrodes in PEMFC was verified. Values between 56 and 59 % of ionomer related to the mass of the catalyst layer resulted in the highest current densities. It was found that the optimum value was strongly dependent on the work potential and temperature. Current density values of 214 mA.cm-2 were obtained at 500 mV, 85 °C and 1 atm for MEAs with Pd/C on both electrodes of PEMFC. With commercial Pt/C only on the cathode side, a value of 745 mA.cm-2 was reached. For comparison, platinum anodes running under the same conditions showed only 13.9 % higher performance than palladium, indicating that improvements in the synthesis method can enhance the performance for palladium getting to be similar to platinum on the hydrogen oxidation reaction. Indeed, these results proved that, from an economic point of view, it is feasible to apply palladium on anodes to replace platinum, although an adequate assessment of durability is still to be investigated.