JULIO CESAR M. DA SILVA

JULIO CESAR M. DA SILVA

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Electrocatalysts for direct ethanol fuel cells
2018 - SILVA, JULIO C.M. da; LOPES, THIAGO; OLIVEIRA NETO, ALMIR; SPINACE, ESTEVAM V.
In this chapter, an overview of electro-catalysts for direct ethanol fuel cells based on polymer electrolyte membranes is presented, with special attention given to the alkaline anion exchange membrane-based devices. Considering the anodic reaction, it is evidenced that a substantial effort has been dedicated towards increasing the fuel cell efficiency by developing electrocatalysts with higher catalytic activity. In this sense, palladium is pointed out as a promising substitute to platinum with regards to electrocatalytic activity, price and element availability. Furthermore, palladium-based nanoparticles are pointed out as the electrocatalysts with the highest electrocatalytic activity for ethanol electro-oxidation in alkaline media. Taking into account the support materials for the electrocatalysts nanoparticles, it was possible to observe an evolution in carbon-based materials, first carbon nanotubes overcame the carbon black, where more recently, graphene is addressed as the best support choice for catalysts nanoparticles. Different efforts have been made to improve the properties of the support materials, such as doping with nitrogen or with metal oxides like TiO2, for example. Considering the cathode materials, the main goal is to develop catalysts with enhanced activity to the oxygen reduction reaction as well as tolerance to ethanol molecules that crossover the electrolyte membrane.
Palladium nanoparticles supported on phosphorus-doped carbon for ethanol electro-oxidation in alkaline media
2018 - SILVA, JULIO C.M.; FREITAS, ISABEL C. de; NETO, ALMIR O.; SPINACE, ESTEVAM V.; RIBEIRO, VILMARIA A.
Palladium nanoparticles supported on carbonVulcan XC72 (Pd/C) and on phosphorus-doped carbon (Pd/P-C) were prepared by an alcohol reduction process. X-ray diffractograms of Pd/C and Pd/P-C showed the typical face-centered cubic (fcc) structure of Pd. The crystallite sizes of Pd fcc phase were around 8 nm for both samples. X-ray photoelectron spectroscopy revealed to Pd/C and Pd/P-C that Pd was found predominantly in the metallic state and to Pd/P-C, the presence of P increases the amount of oxygen on the electrocatalyst surface. The activity and stability of the electrocatalyts for ethanol electro-oxidation in alkalinemedium was investigated by cyclic voltammetry and chronoamperometry experiments. The peak current density on Pd/P-C was 50% higher than on Pd/C, while the current density measured after 30 min at − 0.35 V vs. Hg/ HgO was 65% higher on Pd/P-C than on Pd/C. The enhancement of the catalytic activity of Pd/P-C electrocatalyst might be related to the presence of higher amounts of oxygen species on the surface, which could contribute to the oxidation of intermediates formed during ethanol electro-oxidation process.
Carbon-supported Pt nanoparticles with (100) preferential orientation with enhanced electrocatalytic properties for carbon monoxide, methanol and ethanol oxidation in acidic medium
2017 - ANTONIASSI, R.M.; SILVA, J.C.M.; LOPES, T.; OLIVEIRA NETO, A.; SPINACE, E.V.
The relationship between atomic arrangement (morphology) and catalytic activity/selectivity in heterogeneous catalysis is an actual hot research topic concerning a range of reactions. This article evaluates one-pot synthesized carbon-supported Pt nanoparticles with preferential Pt(100) orientation prepared with an environmentally friendly shape-directing agent and compares this with Pt/C polycrystalline towards CO, methanol and ethanol electrooxidation reactions. The preferentially cubic nanomaterial (Pt-(100)) interacts differently with CO molecule and presents distinct hydrogen adsorption/desorption characteristics. Pt/C polycrystalline exhibits a CO-stripping profile with one peak at 0.86 V in contrast to three peaks between 0.75 and 0.86 V and a pre-peak at about 0.40.6 V for the Pt/C-(100), which may be associated to the unique surface characteristics of the cubic material. The onset potentials towards carbon monoxide, methanol and ethanol electro-oxidation reactions on Pt/C-(100) are 22%, 21% and 54% lower than on Pt/C polycrystalline. The ratio between the forward per backward peak current densities for the electrooxidation of ethanol and methanol are higher on Pt/C-(100), which suggests that Pt(100) domains are more tolerant to undergo poisoning by the intermediates/by-products formed in these reactions. Proton exchange membrane fuel cells fed with pure hydrogen and with a H-2/CO mixture show superior performance using Pt/C-(100) as anode in comparison to Pt/C polycrystalline catalyst. These results evidence that controlling the morphology of Pt nanoparticles is a key factor to improve the catalytic activity of the polymer electrolyte fuel cell fueled with fuels that involve the electro-oxidation of CO.
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.
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.
Oxidation of small organics molecules mixtures on PtCeO2/C
2011 - SOUZA, R.F.B. de; SILVA, J.C.M.; D'VILLA SILVA, M.; SIMÕES, F.C.; NETO, A.O.; SANTOS, M.C.
PtSnCe/C and PtSn/C + Ce/C electrocatalysts for ethanol oxidation reaction
2012 - SOUZA, R.F.B. de; SILVA, J.C.M.; ASSUMPCAO, M.H.M.T.; OLIVEIRA NETO, A.; SANTOS, M.C.
Preparation of Pt/C, Pt/C-Sbsub(2)Osub(5)-SnOsub(2), Pt/C-Insub(2)Osub(3)-SnOsub(2) electrocatalysts by borohydride reduction process for ethanol electro-oxidation
2012 - SOUZA, R.F.B. de; SILVA, J.C.M.; HENRIQUE, R.S.; AYOUB, J.M.S.; PIASENTIN, R.M.; LINARDI, M.; SPINACE, E.V.; SANTOS, M.C.; OLIVEIRA NETO, A.
Atividade catalítica de nanopartículas de óxido de cério e vânadio para a eletrossíntese de peróxido de hidrogênio
2012 - SOUZA, RODRIGO F.B. de; SILVA, JULIO C.M.; ASSUMPCAO, MONICA H.M.T.; OLIVEIRA NETO, ALMIR; SANTOS, MAURO C. dos
Ethanol electro-oxidation in alkaline medium using Pd/C, Au/C and PdAu/C electrocatalysts prepared by electron beam irradiation
2013 - GERALDES, ADRIANA N.; SILVA, DIONISIO F. da; SEGURA PINO, EDDY; SILVA, JULIO C.M. da; SOUZ, RODRIGO F.B. de; SPINACE, ESTEVAM V.; OLIVEIRA NETO, ALMIR; LINARDI, MARCELO; SANTOS, MAURO C. dos