Edson A. Ticianelli

Electrochemistry

41.34

Publications

  • Flávio R. Nikkuni · Laetitia Dubau · Edson A. Ticianelli · Marian Chatenet
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    ABSTRACT: Identical-location transmission electron microscopy (ILTEM) coupled with X-ray energy dispersive spectroscopy (X-EDS) analyses were used to characterize the changes in the morphology and composition of Pt and Pt3Co nanoparticles deposited on high surface area carbon (Vulcan XC72) before and after electrochemical ageing tests performed in polymer electrolyte environment, using a “dry cell”. The Pt/C and Pt3Co/C electrocatalysts are modified upon electrochemical ageing, following changes in particle size, geometry, and composition; these changes are however milder to what happens upon aging in H2SO4 electrolyte, because of the lack of liquid water, a reactant in both carbon corrosion and Pt (Pt3Co) corrosion/dissolution reactions. The negative vertex potential of the ageing procedure also matters: Pt redeposition occurs at 0.1 V vs. RHE and not at 0.6 V vs. RHE, while carbon corrosion is emphasized after incursions at the lower vertex potential, in agreement to what demonstrated in liquid electrolyte. Besides, the presence of Co in Pt3Co alloys enables to somewhat slow-down the Pt corrosion from Pt3Co/C electrocatalysts, since cobalt acts as a sacrificial anode, which also lowers carbon corrosion.
    Applied Catalysis B Environmental 10/2015; 176. DOI:10.1016/j.apcatb.2015.04.035 · 7.44 Impact Factor
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    ABSTRACT: Although ethanol can be directly employed as fuel on polymer-electrolyte fuel cells (PEMFC), its low oxidation kinetics in the anode and the crossover to the cathode lead to a substantial reduction of energy conversion efficiency. However, when fuel cell driven vehicles are considered, the system may include an on board steam reformer for converting ethanol into hydrogen, but the hydrogen produced contains carbon monoxide, which limits applications in PEMFCs. Here, we present a system consisting of an ethanol dehydrogenation catalytic reactor for producing hydrogen, which is supplied to a PEMFC to generate electricity for electric motors. A liquid by-product effluent from the reactor can be used as fuel for an integrated internal combustion engine, or catalytically recycled to extract more hydrogen molecules. Power densities comparable to those of a PEMFC operating with pure hydrogen are attained by using the hydrogen rich stream produced by the ethanol dehydrogenation reactor.
    Journal of Power Sources 10/2015; 294. DOI:10.1016/j.jpowsour.2015.06.086 · 6.22 Impact Factor
  • Ayaz Hassan · Valdecir Antonio Paganin · Edson Antonio Ticianelli
    08/2015; DOI:10.1007/s12678-015-0269-7
  • Pedro F. B. D. Martins · Edson A. Ticianelli
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    ABSTRACT: The degradation of Pt-based electrocatalysts used in proton-exchange membrane fuel cell (PEMFC) cathodes is one of the main issues restricting the widespread application of PEMFCs as energy converters. This work aims to contribute to the improvement of the stability of platinum nanoparticles (Pt NPs) by modifying the support to which they are anchored. Thus, syntheses of catalyst supports based on molybdenum oxides and carbon are carried out, followed by impregnation of the supports with Pt NPs. The Pt/MoO3–C catalyst shows the highest specific activity in the oxygen reduction reaction (ORR), and this must be because of synergistic metal–support effects. Regarding the electrochemical stability of the materials, it is observed that, in principle, none of the Mo oxides decrease the extent of Pt degradation. However, after comparing the specific ORR activities before and after electrochemical ageing, it is concluded that Pt/MoO2*–C is a more stable material compared to Pt/C and Pt/MoO3–C.
    07/2015; DOI:10.1002/celc.201500196
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    ABSTRACT: Ni-based alloys were prepared by using the oxalate method and subsequent in-situ reduction. The crystallographic phase and microstructure of the catalysts were investigated. These bimetallic alloys were mixed with gadolinium-doped ceria in order to obtain a composite material with mixed electronic-ionic conductivity. Catalytic and electrocatalytic properties of the composite materials for the conversion of ethanol were investigated. Electrochemical tests were carried out by utilizing the Ni-based alloy/CGO cermet as a barrier layer in a conventional anode-supported solid oxide fuel cell (SOFC). A comparative study between the modified cells and a conventional anode-supported SOFC without the protective layer was made. The aim was to efficiently convert the fuel directly into electricity or syngas (H2 and CO) just before the conventional anode support. In accordance with the ex-situ catalytic tests, the SOFC anode modified with Ni-Co/CGO showed superior performance towards the direct utilization of dry ethanol than the bare anode and that modified with Ni-Cu/CGO. A peak power of 550 mW cm−2 was achieved with the dry ethanol-fed Ni-Co/CGO pre-layer modified-cell at 800 °C. A total low frequency resistance of
    Journal of Applied Electrochemistry 07/2015; 45(7). DOI:10.1007/s10800-015-0849-5 · 2.15 Impact Factor
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    ABSTRACT: This study aims at analyzing the potential application of the liquid effluent coming from a catalytic ethanol dehydrogenation reactor as a fuel blend or additive for internal combustion engines, and also of the hydrogen produced, as fuel for a polymer electrolyte fuel cell (PEMFC). The liquid effluent is obtained by the catalytic reaction of ethanol over Cu/ZrO2 at different contact times of the reactant with the catalyst bed. Subsequently, high-performance liquid chromatography analysis and heat of combustion measurements are used to analyze the composition and the heat of combustion of the liquid effluent trapped by cold condensation at 271.65 K. In parallel, the effect of the presence of residual parts of the constituents of the liquid effluent in the H2 stream on the operational characteristics of a PEMFC having a Pt/C anode and cathode is investigated. Results show that the liquid fuel blend obtained from ethanol dehydrogenation has a heat of combustion higher than that of ethanol, and it is essentially formed by un-reacted ethanol, acetaldehyde and ethyl acetate. Thermodynamic calculations evidence a good agreement with the liquid effluent composition and its respective combustion enthalpy. Polarization curves of a PEMFC supplied with hydrogen containing 1000 ppm of acetaldehyde and ethyl acetate evidence performances comparable to that of the same system when fed with pure hydrogen, while with ethanol significant loss of activity is observed.
    International Journal of Hydrogen Energy 06/2015; DOI:10.1016/j.ijhydene.2015.05.071 · 2.93 Impact Factor
  • Ayaz Hassan · Valdecir Antonio Paganin · Edson Antonio Ticianelli
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    ABSTRACT: Pt supported on tungsten carbide-impregnated carbon (Pt/WC/C) is evaluated for hydrogen oxidation reaction in hydrogen/oxygen polymer electrolyte fuel cell at two different temperatures (85 and 105 °C), in absence and presence of 100 ppm CO. Carbon supported PtW, prepared by a formic acid reduction method is also evaluated for comparison. At 85 °C, the initial hydrogen oxidation activity in the presence of 100 ppm CO is higher for Pt/WC/C, showing a CO induced overpotential of 364 mV for 1 A cm−2 of current density as compared to an overpotential of 398 mV for PtW/C. As expected, an increase in CO tolerance is observed with the increase in cell temperature for both the catalysts. The increased CO tolerance of Pt/WC/C catalyst is in agreement with CO stripping experiments, for which the CO oxidation potentials occurred at lower potentials at three different temperatures (25, 85 and 105 °C) in comparison to PtW/C. The stability of both electrocatalysts is evaluated by an accelerated stress test and the results show a better stability for Pt/WC/C catalyst. On the basis of cyclic voltammograms and polarization curves, it is concluded that Pt/WC/C is more stable than PtW/C and can be used as alternative anode catalyst in PEMFC, especially at high temperatures.
    Applied Catalysis B Environmental 04/2015; 165:611-619. DOI:10.1016/j.apcatb.2014.10.068 · 7.44 Impact Factor
  • Ayaz Hassan · Valdecir Antonio Paganin · Alejo Carreras · Edson Antonio Ticianelli
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    ABSTRACT: The activity, stability and CO tolerance of molybdenum carbide-based electrocatalyts were studied in anodes of proton exchange membrane fuel cells (PEMFCs). To this purpose, carbon-supported molybdenum carbide (Mo2C/C) was prepared by an ultrasonic method, and was used as catalyst support in the anode of a PEMFC. Pt and PtMo nanoparticles were deposited on this Mo2C/C by the formic acid reduction method. The physical properties of the resulting electrocatalysts were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray absorption near edge structure (XANES), scanning electron microscopy (SEM) and wavelength dispersive spectroscopy (WDS). Electrochemical characterizations were carried out by single cell polarization measurements, CO stripping, cyclic voltammetry (CV) and online mass spectrometry (OLMS). CV and OLMS experiments were performed to evaluate the stability and CO tolerance of the electrocatalysts. The results obtained for the carbide-based electrocatalysts were compared with those obtained for carbon-supported PtMo and Pt electrocatalysts. It was observed that Pt and PtMo supported on Mo2C/C present a better stability than PtMo supported on carbon. CV and WDS results evidenced a partial dissolution of Mo from the anode and its migration toward cathode during the cell operation. On the basis of polarization measurements and cyclic voltammograms, it was concluded that the stability of anode electrocatalysts can be improved by the use of molybdenum carbide as catalyst support.
    Electrochimica Acta 10/2014; 142:307-316. DOI:10.1016/j.electacta.2014.07.142 · 4.50 Impact Factor
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    ABSTRACT: The degradation mechanisms of nanostructured Pt3Co/C electrocatalysts aged in dry electrochemical environment using a Nafion (R) 115 membrane as polymer electrolyte were characterized by Identical Location Transmission Electron Microscopy, in conditions that perfectly mimic real PEMFC operation. The structural, morphological and compositional changes of the Pt3Co/C nanoparticles occurring during an accelerated stress test were bridged to changes of their intrinsic kinetics toward the oxygen reduction reaction in Nafion (R) 115 electrolyte, thanks to an ultramicroelectrode with cavity loaded with the catalyst. The unique setup used herein further enabled to compare the Nafion (R) environment with conventional liquid electrolyte in which accelerated stress tests are usually performed. Although the Pt3Co/C nanoparticles are modified upon aging at Nafion (R) interface, the degradation processes are milder and different than those observed in liquid electrolyte, mostly following the absence of liquid water and the lack of ion mobility within the Nafion (R) membrane.
    Applied Catalysis B Environmental 09/2014; s 156–157:301–306. DOI:10.1016/j.apcatb.2014.03.029 · 7.44 Impact Factor
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    ABSTRACT: This work provides insights into the processes involved in the borohydride oxidation reaction (BOR) in alkaline media on metal hydride alloys formed by LaNi4.7 Sn0.2 Cu0.1 and LaNi4.78 Al0.22 with and without deposited Pt, Pd, and Au. The results confirm the occurrence of hydrolysis of the borohydride ions when the materials are exposed to BH4 (-) and a continuous hydriding of the alloys during BH4 (-) oxidation measurements at low current densities. The activity for the direct BOR is low in both bare metal hydride alloys, but the rate of the BH4 (-) hydrolysis and the hydrogen-storage capacity are higher, while the rate of H diffusion is slower for bare LaNi4.78 Al0.22 . The addition of Pt and Pd to both alloys results in an increase of the BH4 (-) hydrolysis, but the H2 formed is rapidly oxidized at the Pt-modified catalysts. In the case of Au modification, a small increase in the BH4 (-) hydrolysis is observed as compared to the bare alloys. The presence of Au and Pd also leads to a reduction of the rates of alloy hydriding/de-hydriding.
    ChemPhysChem 07/2014; 15(10). DOI:10.1002/cphc.201400094 · 3.36 Impact Factor
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    ABSTRACT: A nickel–copper alloy is prepared by using the oxalate method and subsequent in situ reduction. The bimetallic alloy is mixed with gadolinium-doped ceria (CGO) to obtain a composite material with mixed electronic–ionic conductivity. The catalytic and electrocatalytic properties of the composite material for ethanol conversion are described. Different conditions to simulate bio-ethanol feed operation are selected. Electrochemical tests are performed by utilizing the NiCu/CGO cermet as a barrier layer in a conventional anode-supported solid-oxide fuel cell (AS-SOFC). A comparative study between the modified cell and a conventional AS-SOFC without the protective layer is made. A maximum power density of 277 mW cm−2@0.63 V is recorded in the presence of a mixture of ethanol–water for a cell containing the protective anodic layer compared with 231 mW cm−2@0.64 V for a bare cell under the same conditions. This corresponds to a 20 % increase in performance.
    05/2014; 1(8). DOI:10.1002/celc.201402017
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    Ayaz Hassan · Alejo Carreras · Jorge Trincavelli · Edson Antonio Ticianelli
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    ABSTRACT: The effect of heat treatment on the activity, stability and CO tolerance of PtMo/C catalysts was studied, due to their applicability in the anode of proton exchange membrane fuel cells (PEMFCs). To this purpose, a carbon supported PtMo (60:40) alloy electrocatalyst was synthesized by the formic acid reduction method, and samples of this catalyst were heat-treated at various temperatures ranging between 400 and 700 °C. The samples were characterized by temperature programmed reduction (TPR), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), cyclic voltammetry (CV), scanning electron microscopy (SEM) and wavelength dispersive X-ray spectroscopy (WDS). Cyclic voltammetry was used to study the stability, and polarization curves were used to investigate the performance of all materials as CO tolerant anode on a PEM single cell text fixture. The catalyst treated at 600 °C, for which the average crystallite size was 16.7 nm, showed the highest hydrogen oxidation activity in the presence of CO, giving an overpotential induced by CO contamination of 100 mV at 1 Acm-2. This catalyst also showed a better stability up to 5000 potential cycles of cyclic voltammetry, as compared to the untreated catalyst. CV, SEM and WDS results indicated that a partial dissolution of Mo and its migration/diffusion from the anode to the cathode occurs during the single cell cycling. Polarization results showed that the catalytic activity and the stability can be improved by a heat treatment, in spite of a growth of the catalyst particles.
    Journal of Power Sources 02/2014; 247:712-720. DOI:10.1016/j.jpowsour.2013.08.138 · 6.22 Impact Factor
  • Flavio R. Nikkuni · Marian Chatenet · Edson A. Ticianelli · Laetitia Dubau
    224th ECS Meeting; 10/2013
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    Amanda Cristina Garcia · Edson A. Ticianelli
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    ABSTRACT: he activity of Pt catalysts dispersed on tungsten carbide (WC) prepared with a high surface area carbon with two different WC/C ratios is investigated for the oxygen reduction reaction (ORR) in alkaline electrolyte. The electrochemical methods employed are cyclic voltammetry (CV) and steady-state polarization carried out on an ultrathin catalyst layer deposited on the disk of a rotating ring-disk electrode. The PtWC-based catalysts show higher activity for the ORR compared to Pt/C, also involving a transfer of 4 electrons per oxygen molecule. CV and X-ray absorption near edge structure spectroscopy (XANES) results for the PtWC-based materials indicate weaker Pt–OHx interaction in these materials, resulting in a lower Pt-oxide coverage and explaining the increased rate of the ORR, as compared to Pt/C.
    Electrochimica Acta 09/2013; 106(1):453-459. DOI:10.1016/j.electacta.2013.05.128 · 4.50 Impact Factor
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    ABSTRACT: In the present paper we investigated the effect of adsorbed PVA on Pt electrodes on classic electrochemical processes such as hydrogen UPD, oxygen reduction and CO electro-oxidation. Upon adsorption PVA blocks roughly 50% of the hydrogen sites and can not be removed from the Pt surface through cycling in the potential range of 0.05–1.0 V vs. RHE. Potentiodynamic experiments under controlled hydrodynamic conditions provided by rotating disk electrode experiments showed a negative impact of the adsorbed PVA on the oxygen reduction reaction (ORR). Cyclic-voltammetry results revealed that not even CO was able to remove PVA from the Pt surface. Regarding the oxidation of CO, the adsorbed polymer positively shifted the CO oxidation peak potential, therefore higher potentials are required to free the Pt surface from CO poisoning. In situ Fourier transform infrared spectroscopy evidenced that the presence of PVA shifted the linearly bound CO frequency toward higher wavenumbers, a process found to be independent of the Pt surface orientation. In situ electrochemical X-ray absorption spectroscopy results showed that PVA also impacted the electronic properties of platinum by decreasing the occupancy of the Pt conducting 5d band. Our findings clearly support the efforts toward understanding the nature of the interaction between polymers and metallic surfaces as well as the impact on technological applications (e.g. in PEMFCs).
    Electrochimica Acta 08/2013; 104:358–366. DOI:10.1016/j.electacta.2012.12.127 · 4.50 Impact Factor
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    ABSTRACT: A number of fuel cell relevant reactions are known to undergo kinetic instabilities under certain conditions. The majority of the experiments in such systems have been performed in liquid electrolyte systems on half-cell setups. Results for proton exchange membrane fuel cells fed with H2/CO mixtures at the anode show that there can be a range of gas flow rate and current density where spontaneous potential oscillations take place. Despite the recent developments in this area, there are still many mechanistic aspects underlying the emergence of electrochemical oscillations that remain unknown. In the present contribution, we report results on the CO2 production during the oxidation of carbon monoxide-containing hydrogen in a proton exchange membrane fuel cell, as measured by online mass spectrometry. By extensive fitting and careful consideration of the proposed mechanism, we were able to estimate the coverage of hydrogen and CO during the oscillations. As no other approach seems capable to probe the adsorbate coverage in an operando fuel cell, our analyses access experimental hidden information that can be of high value for fuel cell research.
    Journal of Solid State Electrochemistry 07/2013; 17(7). DOI:10.1007/s10008-013-2048-9 · 2.23 Impact Factor
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    Waldemir J. Paschoalino · Edson A. Ticianelli
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    ABSTRACT: In this study, LaNi4.7Sn0.2Cu0.1 metal hydride alloys, with and without surface deposits of Pt, are investigated as electrocatalysts for the borohydride oxidation reaction (BOR) in alkaline media. Results obtained for LaNi4.78Al0.22 and LaNi4.78Mn0.22 are used for comparison. It is observed that wet exposition to hydrogen or sodium borohydride lead to some hydriding of the metal hydride alloy particles, particularly that with a coating of Pt. In the presence of borohydride ions, the hydrided charged alloys present more negative potentials for the (boro)hydride oxidation process, and these enhancements are significantly larger for the Pt-coated material. In the potential range of interest, the results demonstrate considerable activity for the BOR, but just for the alloy with Pt. In the presence of borohydride ions in the solution there is a continuous hydriding the alloy during the discharge of the metal hydride electrode. Differential electrochemical mass spectrometry (DEMS) measurements showed that there is formation of H2, either by hydrolysis or by partial oxidation of the borohydride ions, but in the absence of Pt the hydrolysis process is quite slow.
    International Journal of Hydrogen Energy 06/2013; 38(18):7344–7352. DOI:10.1016/j.ijhydene.2013.04.036 · 2.93 Impact Factor
  • F.R. Nikkuni · S.F. Santos · E.A. Ticianelli
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    ABSTRACT: SUMMARY Magnesium – nickel alloys have been considered an alternative for AB5 and AB2-type alloys in nickel–metal hydride batteries due to their larger maximum discharge capacities, but their low stability in alkaline solution has hindered their use in commercial cells. Aiming to improve the electrode performance of the Mg55Ni45 alloy, we investigated the simultaneous addition of Ti and a noble metal (Pd and Pt) as alloying elements. The investigated system has general composition Mg49Ti6Ni(45-x)Mx, where M is Pd or Pt, and x assumed values of 0, 2.0 and 4.0 at.%. The electrochemical measurements showed that the Mg49Ti6Ni41Pd4 alloy has the best electrode performance among the studied alloys, reaching 431 mA h g−1 of maximum discharge capacity at the first cycle of charge/discharge. After 10 and 20 cycles, this alloy presented relative discharge capacities of 84 and 77% of the initial one, respectively. The electrode performance of the investigated alloys is discussed in light of results of structural characterization by transmission electron microscopy and X-ray diffraction. Copyright © 2013 John Wiley & Sons, Ltd.
    International Journal of Energy Research 06/2013; 37(7). DOI:10.1002/er.3008 · 2.74 Impact Factor
  • 223th ECS Meeting; 05/2013
  • 223th ECS Meeting; 05/2013

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