RICARDO MARCELO PIASENTIN

RICARDO MARCELO PIASENTIN

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Comparison of various atomic compositions of Au@Pd/C, Pd/C, and AuPd/C electrocatalysts for direct ethanol fuel cells
2020 - FONTES, ERIC H.; NANDENHA, JULIO; PIASENTIN, RICARDO M.; SOUZA, RODRIGO F.B. de; NETO, ALMIR O.
Pd/C, Au@Pd/C (core-shell), and AuPd/C (AR—consisting in Au microparticles) were used as electrocatalysts for ethanol oxidation in alkaline medium. A synergistic effect between Au and Pd atoms in Au@Pd/C makes the binding between ethanol and Au@Pd/C stronger. This leads to product formation in higher potentials and can be useful to select ethanol products. We also showed that the atomic composition of the electrocatalysts to be used in fuel cells and in powder form to be used in electrochemical experiments are very similar, reaching high values of correlation. The depth profiling X-ray photoelectron spectroscopy for the anode catalysts to be used in fuel cells can provide new insights about ethanol oxidation in direct ethanol fuel cells (DEFCs), for instance, metal oxide species can act in fuel cells environment. In terms of electric generation, Au@Pd/C presented a better performance in electrochemical experiments; the current density was about 1.6 times higher than the peak current density obtained for Pd/C. In terms of electrochemical stability, Au@Pd/C presented better final current density when compared to Pd/C and AuPd/C electrocatalysts. However, in DEFC experiments, Pd/C showed better performance.
Partial oxidation of methane and generation of electricity using a PEMFC
2019 - NANDENHA, J.; PIASENTIN, R.M.; SILVA, L.G.M.; FONTES, E.H.; NETO, A.O.; SOUZA, R.F.B. de
The aim of this work was to produce methanol through partial oxidation of methane. The gas fed in a solid membrane reactor- PEM fuel cell type (H2/H2O2 + CH4) has been used for electrosynthesis of methanol at room temperature, with electricity cogeneration as a benefit. It was observed that the current density measured when injected CH4 in the cathode decreased about 45%. This occurs due to the conversion of methane inmethanol in some ranges of potentials. In the other hand, in lower ranges of cell potential, formaldehyde was found. In this work, methane was injected on the cathode together with H2O2 solution, where it was observed that the catalytic layer adsorbed CH4 and H2O2 in active sites, which produced OH− radicals that reacted with the hydrocarbon.
Direct oxidation of methane at low temperature using Pt/C, Pd/C, Pt/C-ATO and Pd/C-ATO electrocatalysts prepared by sodium borohydride reduction process
2018 - NANDENHA, J.; FONTES, E.H.; PIASENTIN, R.M.; FONSECA, F.C.; NETO, A.O.
The main objective of this paper was to characterize the voltammetric profiles of the Pt/C, Pt/C-ATO, Pd/C and Pd/C-ATO electrocatalysts and study their catalytic activities for methane oxidation in an acidic electrolyte at 25°C and in a direct methane proton exchange membrane fuel cell at 80°C. The electrocatalysts prepared also were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The diffractograms of the Pt/C and Pt/C-ATO electrocatalysts show four peaks associated with Pt face-centered cubic (fcc) structure, and the diffractograms of Pd/C and Pd/C-ATO show four peaks associated with Pd face-centered cubic (fcc) structure. For Pt/C-ATO and Pd/C-ATO, characteristic peaks of cassiterite (SnO2) phase are observed, which are associated with Sb-doped SnO2 (ATO) used as supports for electrocatalysts. Cyclic voltammograms (CV) of all electrocatalysts after adsorption of methane show that there is a current increase during the anodic scan. However, this effect is more pronounced for Pt/C-ATO and Pd/C-ATO. This process is related to the oxidation of the adsorbed species through the bifunctional mechanism, where ATO provides oxygenated species for the oxidation of CO or HCO intermediates adsorbed in Pt or Pd sites. From in situ ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) experiments for all electrocatalysts prepared the formation of HCO or CO intermediates are observed, which indicates the production of carbon dioxide. Polarization curves at 80°C in a direct methane fuel cell (DMEFC) show that Pd/C and Pt/C electroacatalysts have superior performance to Pd/C-ATO and Pt/C-ATO in methane oxidation.
The effect of antimony-tin and indium-tin oxide supports on the catalytic activity of Pt nanoparticles for ammonia electro-oxidation
2016 - SILVA, JULIO C.M.; PIASENTIN, RICARDO M.; SPINACE, ESTEVAM V.; NETO, ALMIR O.; BARANOVA, ELENA A.
Platinum nanoparticles supported on carbon (Pt/C) and carbon with addition of ITO (Pt/C-ITO (In2O3)(9)center dot(SnO2)(1)) and ATO (Pt/C-ATO (SnO2)(9).(Sb2O5)(1)) oxides were prepared by sodium borohydride reduction method and used for ammonia electro-oxidation reaction (AmER) in alkaline media. The effect of the supports on the catalytic activity of Pt for AmER was investigated using electrochemical (cyclic voltammetry and chronoamperometry) and direct ammonia fuel cell (DAFC) experiments. X-ray diffraction (XRD) showed Pt peaks attributed to the face-centered cubic (fcc) structure, as well as peaks characteristic of In2O3 in ITO support and cassiterite SnO2 phase of ATO support. According to transmission electron micrographs the mean particles sizes of Pt over carbon were 5.4, 4.9 and 4.7 nm for Pt/C, Pt/C-ATO and Pt/C-ITO, respectively. Pt/C-ITO catalysts showed the highest catalytic activity for ammonia electrooxidation in both electrochemical and fuel cell experiments. We attributed this to the presence of In2O3 phase in ITO, which provides oxygenated or hydroxide species at lower potentials resulting in the removal of poisonous intermediate, i.e., atomic nitrogen (N-ads) and promotion of ammonia electrooxidation. (C) 2016 Elsevier B.V. All rights reserved.
Ethanol electro-oxidation on PtSn/C-ATO electrocatalysts
2012 - AYOUB, J.M.S.; SOUZA, R.F.B. de; SILVA, J.C.M.; PIASENTIN, R.M.; SPINACE, E.V.; SANTOS, M.C.; OLIVEIRA NETO, A.
Preparation of Pt/C-Insub(2)Osub(3).SnOsub(2) electrocatalysts by borohydride reduction process for ethanol electro-oxidation
2012 - HENRIQUE, R.S.; SOUZA, R.F.B. de; SILVA, J.C.M.; AYOUB, J.M.S.; PIASENTIN, R.M.; LINARDI, M.; SPINACE, E.V.; SANTOS, M.C.; NETO, A.O.
PtRu/C and PtRuBi/C electrocatalysts prepared in two different ways by borohydride reduction for ethanol electro-oxidation
2010 - BRANDALISE, MICHELE; TUSI, MARCELO M.; PIASENTIN, RICARDO M.; LINARDI, MARCELO; SPINACE, ESTEVAM V.; OLIVEIRA NETO, ALMIR