RODRIGO FERNANDO BRAMBILLA DE SOUZA

RODRIGO FERNANDO BRAMBILLA DE SOUZA

Página do item completo

Resultados de Busca

Agora exibindo 1 - 10 de 18

Electrochemical and in situ ATR-FTIR studies of ethanol electro-oxidation in alkaline medium using PtRh/C electrocatalysts
2015 - FONTES, E.H.; PIASENTIN, R.M.; AYOUB, J.M.S.; SILVA, J.C.M. da; ASSUMPCAO, M.H.M.T.; SPINACE, E.V.; NETO, A.O.; SOUZA, R.F.B. de
PtBi/C electrocatalysts for formic acid electro-oxidation in acid and alkaline electrolyte
2015 - YOVANOVICH, M.; PIASENTIN, R.M.; AYOUB, J.M.S.; NANDENHA, J.; FONTES, E.H.; SOUZA, R.F.B. de; BUZZO, G.S.; SILVA, J.C.M.; SPINACE, E.V.; ASSUMPCAO, M.H.M.T.; NETO, A.O.; SILVA, S.G. da
PtAu/C electrocatalysts as anodes for direct ammonia fuel cell
2015 - SILVA, JULIO C.M.; SILVA, SIRLANE G. da; SOUZA, RODRIGO F.B. de; BUZZO, GUILHERME S.; SPINACE, ESTEVAM V.; OLIVEIRA NETO, ALMIR; ASSUMPCAO, MONICA H.M.T.
PtAu/C electrocatalysts prepared by borohydride reduction method with different Pt:Au atomic ratios (50:50 and 70:30) were tested as work electrodes/anodes in electrochemical experiments and also using a direct ammonia fuel cell (DAFC). X-ray diffraction patterns showed the formation of PtAu alloy while transmission electron micrographs showed the particles sizes between 5.8 and 6.4 nm. PtAu/C 70:30 presented the best results showing a current density about 20% higher when compared to Pt/C in voltammetry experiments and a power density about 60% higher than Pt/C using DAFC, while Au/C showed practically no activity in both experiments. The best results obtained with PtAu/C (70:30) could be explained by the electronic effect (PtAu alloy) associated with adsorbed hydroxyl species (AuOHads) and also the lower Au-N energy adsorption.
Oxidation of ammonia using PtRh/C electrocatalysts: fuel cell and electrochemical evaluation
2015 - ASSUMPCAO, MONICA H.M.T.; PIASENTIN, RICARDO M.; HAMMER, PETER; SOUZA, RODRIGO F.B. de; BUZZO, GUILHERME S.; SANTOS, MAURO C.; SPINACE, ESTEVAM V.; OLIVEIRA NETO, ALMIR; SILVA, JULIO C.M. da
This study reports on the use of PtRh/C electrocatalysts prepared by the borohydride reduction method with different Pt:Rh atomic ratios: (90:10, 70:30 and 50:50) which was investigated toward the ammonia electro-oxidation considering electrochemical and also direct ammonia fuel cell (DAFC) experiments. The DAFC experiments were conducted using different proportions of NH4OH and KOH as fuels. X-ray diffraction showed the formation of PtRh alloy while transmission electron micrographs showed the particles sizes between 4.1 and 4.5 nm. Among the different NH4OH and KOH concentrations the combination of 3 mol L−1 NH4OH and 3 mol L−1 KOH was the most favorable due to the higher KOH concentration, which increased the electrolyte conductivity, thus, improving the ammonia oxidation. Moreover, among the PtRh/C electrocatalysts the Pt:Rh ratio of 90:10 showed to be the best suited one since it showed a power density almost 60% higher than Pt. X-ray photoelectron spectroscopy results revealed for this catalyst that the nanoparticles contain a high proportion of metallic Pt and Rh phases, supporting the alloy formation between Pt and Rh. The improved fuel cell efficiency can be related to the combination of different effects: the alloy formation between Pt and Rh (electronic effect), suppressing the adsorption strength of poisonous intermediates, and a synergic effect between Pt and Rh at this composition.
Enhanced electrooxidation of ethanol using Pd/C+TiOsub(2) electrocatalysts in akaline media
2015 - SILVA, J.C.M.; BUZZO, G.S.; SOUZA, R.F.B. de; SPINACE, E.V.; NETO, A.O.; ASSUMPCAO, M.H.M.T.
Synthesis of hydroquinone with co-generation of electricity from phenol aqueous solution in a proton exchange membrane fuel cell reactor
2015 - BUZZO, G.S.; RODRIGUES, A.C.B.; SOUZA, R.F.B. de; SILVA, J.C.M.; BASTOS, E.L.; SPINACE, E.V.; NETO, A.O.; ASSUMPCAO, M.H.M.T.
In a proton exchange membrane fuel cell (PEMFC) an aqueous solution containing 100 mg L−1 of phenol was oxidized at the anode using PtRu/C as catalyst while oxygen gas was reduced at cathode using Pt/C as catalyst. The use of a fuel cell as a flow reactor allowed obtaining hydroquinone, an important compound much used in medicine and cosmetic industry, as product with the co-generation of electricity. A conversion of 20% of phenol with the formation of 16 mg L−1 of hydroquinone (80% of selectivity) was observed after 240 min of fuel cell operation at 80 °C.
Ethanol electrooxidation on PdIr/C electrocatalysts in alkaline media: electrochemical and fuel cell studies
2015 - NETO, A.O.; SILVA, S.G. da; BUZZO, G.S.; SOUZA, R.F.B. de; ASSUMPCAO, M.H.M.T.; SPINACE, E.V.; SILVA, J.C.M.
PdIr/C electrocatalysts in different atomic ratios (Pd:Ir 90:10, 70:30, and 50:50), Pd/C and Ir/C supported on Vulcan XC 72 carbon were tested for ethanol electrooxidation in alkaline media. The electrocatalysts were prepared by borohydride reduction method. The electrocatalysts were characterized by Xray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), cyclic voltammetry (CV), and chronoamperometry (CA). The XRD measurements suggested the PdIr alloy formation. EDS analyses showed the real atomic ratios similar to the nominal ones. TEM showed the average particle diameter between 4.6 and 5.8 nm for all compositions prepared. The catalytic activity for ethanol electrooxidation in alkaline medium investigated by CV and CA at room temperature showed that PdIr/C (90:10) exhibited higher performance for ethanol oxidation in comparison with others PdIr/C compositions, Pd/ C and Ir/C, while the experiments on a single direct ethanol alkaline fuel cell at 70 °C showed higher performance for PtIr (70:30). The best results obtained using PdIr/C electrocatalysts may be associated to the electronic effect between Pd and Ir that might cause a decrease of poisoning on catalyst and the occurrence of bifunctional mechanism.
Efeito do conteúdo de TiOsub(2) na eletro-oxidação de etanol em meio alcalino utilizando nanoparticulas de Pt suportadas em mistura física de carbono e TiOsub(2)
2014 - SOUZA, RODRIGO F.B. de; BUZZO, GUILHERME S.; SILVA, JULIO C.M. da; SPINACE, ESTEVAM V.; OLIVEIRA NETO, ALMIR; ASSUMPCAO, MONICA H.M.T.
Amônia: uma nova alternativa para células a combustível alcalinas?
2014 - ASSUMPCAO, MONICA H.M.T.; SILVA, SIRLANE G. da; SOUZA, RODRIGO F.B. de; BUZZO, GUILHERME S.; SPINACE, ESTEVAM V.; NETO, ALMIR O.; SILVA, JULIO C.M. da
Eletrotrooxidação de metanol em nano particulas de Pt: Um estudo da variação do conteúdo da mistura de TiOsub(2) e carbono como suporte em meio alcalino
2014 - ASSUMPCAO, MONICA H.M.T.; SOUZA, RODRIGO F.B. de; SILVA, JULIO C.M. da; SPINACE, ESTEVAM V.; OLIVEIRA NETO, ALMIR; BUZZO, GUILHERME S.