RODRIGO FERNANDO BRAMBILLA DE SOUZA
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Artigo IPEN-doc 29605 Conversion of nitrogen to ammonia using a Cu/C electrocatalyst in a polymeric electrolyte reactor2023 - MAIA, VICTORIA A.; SANTOS, CAMILA M.G.; AZEREDO, NATHALIA F.B.; ZAMBIAZI, PRISCILLA J.; ANTOLINI, ERMETE; NETO, ALMIR O.; SOUZA, RODRIGO F.B. deThe electrochemical conversion of N2 to NH3 using a polymeric electrolyte reactor is a promising method to accelerate the green production of hydrogen carriers. On this basis, we report the efficiency of ammonia production by the nitrogen reduction reaction using a Cu/C catalyst in a polymeric electrolyte membrane reactor. The Cu/C catalyst was prepared by the NaBH4 reduction method and characterized by X-ray diffraction, transmission electron microscopy, cyclic voltammetry, and conversion experiments performed in a polymer electrolyte membrane fuel cell type reactor. The X-ray diffraction results showed the presence of CuO2 and carbon phases, while the TEM images showed a high agglomeration of copper nanoparticles on carbon. The onset potential of nitrogen reduction was near to the Cu (I) to Cu0 reduction peak. Mass spectroscopy was used to observe the production of N2H2 and NH3 and the consumption of N2. Maximum ammonia production was detected at 0.0 V with a NH3 yield rate of 38.4 µg h−1 cm−2 and a faradaic efficiency of 42.57 %.Artigo IPEN-doc 27383 High CO tolerance of Pt nanoparticles synthesized by sodium borohydride in a time-domain NMR spectrometer2020 - RAMOS, A.S.; SANTOS, M.C.L.; GODOI, C.M.; QUEIROZ, L.C. de; NANDENHA, J.; FONTES, E.H.; BRITO, W.R.; MACHADO, M.B.; NETO, A.O.; SOUZA, R.F.B. deThe CO poisoning effect was overcome using a novel synthesis method. This method consists of using sodium borohydride reducing agent assisted by magnetic field and radiofrequency pulses in the time-domain NMR spectrometer. This synthesis was useful to disperse the Pt nanoparticles over the carbon support and to compress the lattice strain of the Pt crystalline structure. Besides that, Pt/C MFP90° showed a multi-CO oxidation component in cyclic voltammetry, and this can avoid the poisoning effect by creating a large availability of CO species to be adsorbed, desorbed, and re-adsorbed. Pt/C MFP90° has also shown the best performance in the PEMFC regarding H2 and CO + H2 experiments.Artigo IPEN-doc 19960 Ethanol oxidation reaction using PtSn/C+ce/C electrocatalysts2014 - SOUZA, R.F.B. de; SILVA, J.C.M.; ASSUMPCAO, M.H.M.T.; NETO, A.O.; SANTOS, M.C.The ethanol oxidation reaction (EOR) was investigated using PtSn/C + Ce/C electrocatalysts in different mass ratios (58:42, 53:47, and 42:58) prepared using the polymeric precursor method. Transmission electron microscopy (TEM) experiments showed particles sizes in the range of 3 to 7 nm. Changes in the net parameters observed for Pt suggest the incorporation of Sn into the Pt crystalline network with the formation of an alloy mixture with the SnO2 phase. Among the PtSn/C + Ce/C catalysts investigated, the 53:47 composition showed the highest activity towards the EOR. In this case, the j versus t curves obtained in the presence of ethanol in acidic media exhibited a current density 90% higher than that observed with the commercial PtSn/C (ETEK). Correspondingly, during the experiments performed on single direct ethanol fuel cells, the maximum power density obtained using PtSn/C + Ce/C (53:47) as the anode was approximately 60% higher than that obtained using the commercial catalyst. FTIR data showed that the observed behavior for ethanol oxidation may be explained in terms of a synergic effect of bifunctional mechanism with electronic effects, in addition to a chemical effect of ceria that provides oxygen-containing species to oxidize acetaldehyde to acetic acid.Artigo IPEN-doc 17244 PtSn/C alloyed and non-alloyed materials: differences in the ethanol electro-oxidation reaction pathways2011 - SILVA, J.C.M.; PARREIRA, L.S.; SOUZA, R.F.B. de; CALEGARO, M.L.; SPINACE, E.V.; NETO, A.O.; SANTOS, M.C.