RAFAEL NOGUEIRA BONIFÁCIO
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Artigo IPEN-doc 29865 Graphene deposited on glass fiber using a non-thermal plasma system2023 - GOMES, PAULO V.R.; BONIFACIO, RAFAEL N.; SILVA, BARBARA P.G.; FERREIRA, JOAO C.; SOUZA, RODRIGO F.B. de; OTUBO, LARISSA; LAZAR, DOLORES R.R.; NETO, ALMIR O.This study reports a bottom-up approach for the conversion of cyclohexane into graphene nanoflakes, which were then deposited onto fiberglass using a non-thermal generator. The composite was characterized using transmission electron microscopy, which revealed the formation of stacked few-layer graphene with a partially disordered structure and a d-spacing of 0.358 nm between the layers. X-ray diffraction confirmed the observations from the TEM images. SEM images showed the agglomeration of carbonaceous material onto the fiberglass, which experienced some delamination due to the synthesis method. Raman spectroscopy indicated that the obtained graphene exhibited a predominance of defects in its structure. Additionally, atomic force microscopy (AFM) analyses revealed the formation of graphene layers with varying levels of porosity.Artigo 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.