Edson A. Ticianelli

Electrochemistry

41.63

Publications

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The borohydride oxidation reaction (BOR) on Pt(111) electrode modified by the electro-deposition of one pseudomorphic Pd layer (Pd1ML/Pt(111)) has been studied in sodium hydroxide solution using cyclic voltammetry in static and dynamic conditions. The results are compared to those obtained at Pt(111) single crystal. Pd1ML/Pt(111) shows an onset potential slightly shifted negative and the BOR current density is overall larger than observed at Pt(111), demonstrating the beneficial influence of the pseudomorphic Pd monolayer towards the BOR. Both surfaces are however very sensitive to surface poisoning by BHx,ad adsorbed intermediates and deactivation by accumulation of hardly-soluble BOR products (BOx species). The forced convection created by rotation of the RDE can nevertheless limit the accumulation of BOR products in the interfacial region, which results in more sustainable BOR performances. Additionally, a modification of the surface signature in sulfuric acid is observed for the two electrodes after BOR, which could suggest that either BOx or BHads species remain and block the electrode surface, or that the surfaces have been reconstructed/de-structured in the strong reducing environment of BOR experiments.
    Full-text · Article · Jan 2016 · Electrochimica Acta
  • Flávio R. Nikkuni · Laetitia Dubau · Edson A. Ticianelli · Marian Chatenet
    [Show abstract] [Hide abstract]
    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.
    No preview · Article · Oct 2015 · Applied Catalysis B Environmental
  • Source
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · Oct 2015 · Journal of Power Sources
  • A. Hassan · R. C. Iezzi · E. A. Ticianelli

    No preview · Article · Oct 2015 · ECS Transactions
  • Ayaz Hassan · Valdecir Antonio Paganin · Edson Antonio Ticianelli
    [Show abstract] [Hide abstract]
    ABSTRACT: In this work, the activity, stability, and CO tolerance of ternary and quaternary electrocatalysts formed by PtMo/C-PtFe/C, PtMo/C-PtRu/C, and PtMo/C-PtRuC-PtFe/C were studied in the anodes of proton exchange membrane fuel cells (PEMFCs). Cyclic voltammetry (CV) was used to study the surface characteristics and stability of the electrocatalysts and polarization curves were used to investigate the performance of PEMFC anodes supplied with pure hydrogen and hydrogen containing 100 ppm CO. Online mass spectrometry (OLMS) and CO stripping experiments were conducted to investigate the CO tolerance mechanism. The PtMo/C-PtRu/C-PtFe/C, PtMo/C-PtFe/C, and PtMo/C-PtRu/C electrocatalysts showed better performance for the oxidation of hydrogen in the presence of hydrogen containing 100 ppm CO as compared to the PtMo/C electrocatalyst. It was found that the partial dissolution of Mo, Ru, and Fe, and their migration/diffusion from the anode to the cathode occur during a CV cycling from 0.1 to 0.7 V vs. RHE at a scan rate of 50 mVs-1 up to total of 5,000 cycles. The results also showed that the stability of PtMo/C-PtRu/C-PtFe/C, PtMo/C-PtFe/C, and PtMo/C-PtRu/C are better than that of PtMo/C.
    No preview · Article · Aug 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: A possible scenario for the future is the utilization of alternative fuels especially those obtained from renewable sources including those derived from biomass. One of the main implications is regarding the consumer's ability to use an increasingly diverse selection of energy sources. Small fuel cells systems, typically less than 10kW, are under consideration for many applications that traditional electric utilities have not supplied widely. In this area, solid oxide fuel cells (SOFCs) may enable new companies to enter the power-generation business as equipment providers or heat and electricity providers. The most common type of SOFC is based on Ni-YSZ as anode and operates at temperatures above 700 °C using H2 or syngas (H2 + CO) produced from a reforming process (internal or external). In this communication, we report the preparation and electrochemical characterization of catalysts having proper behaviour for utilization as protective layer for the anode.
    No preview · Article · Jul 2015 · ECS Transactions
  • Pedro F. B. D. Martins · Edson A. Ticianelli
    [Show abstract] [Hide abstract]
    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.
    No preview · Article · Jul 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Abstract We use the rotating ring disk (RRDE) method to study activity-selectivity relationships for the oxygen reduction reaction (ORR) on Pt(111) modified by various surface coverages of adsorbed CNad (ΘCNad). The results demonstrate that small variations in ΘCNad have dramatic effect on the ORR activity and peroxide production, resulting in "volcano-like" dependence with an optimal surface coverage of ΘCNad = 0.3 ML. These relationships can be simply explained by balancing electronic and ensemble effects of co-adsorbed CNad and adsorbed spectator species from the supporting electrolytes, without the need for intermediate adsorption energy arguments. Although this study has focused on the Pt(111)-CNad/H2SO4 interface, the results and insight gained here are invaluable for controlling another dimension in the properties of electrochemical interfaces.
    No preview · Article · Jul 2015 · Electrochemistry Communications
  • [Show abstract] [Hide abstract]
    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
    No preview · Article · Jul 2015 · Journal of Applied Electrochemistry
  • Source
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · Jun 2015 · International Journal of Hydrogen Energy
  • Ayaz Hassan · Valdecir Antonio Paganin · Edson Antonio Ticianelli
    [Show abstract] [Hide abstract]
    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.
    No preview · Article · Apr 2015 · Applied Catalysis B Environmental
  • Ayaz Hassan · Valdecir Antonio Paganin · Alejo Carreras · Edson Antonio Ticianelli
    [Show abstract] [Hide abstract]
    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.
    No preview · Article · Oct 2014 · Electrochimica Acta
  • [Show abstract] [Hide abstract]
    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.
    No preview · Article · Sep 2014 · Applied Catalysis B Environmental
  • Source
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · Jul 2014 · ChemPhysChem
  • Source
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · May 2014
  • Source
    Ayaz Hassan · Alejo Carreras · Jorge Trincavelli · Edson Antonio Ticianelli
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · Feb 2014 · Journal of Power Sources
  • Flavio R. Nikkuni · Marian Chatenet · Edson A. Ticianelli · Laetitia Dubau

    No preview · Conference Paper · Oct 2013
  • Edson A. Ticianelli · Fabio H. B. Lima
    [Show abstract] [Hide abstract]
    ABSTRACT: Polymer electrolyte membrane fuel cells (PEMFC) that use small organic molecules like methanol and ethanol as fuel in the anode, and oxygen in the cathode, are attracting considerable interest for application in portable electronic devices. Carbon-supported platinum has the highest catalytic activity for oxygen reduction when compared to all other pure metals, and serves as state-of-the-art cathode material in low-temperature fuel cells. Regarding the direct methanol or ethanol fuel cells (DMFC or DEFC), one of the major problems is the alcohol crossover through the polymer electrolyte. The mixed potential, which results from the oxygen reduction reaction and the alcohol oxidation occurring simultaneously, reduces the cell voltage, generates additional water and increases the required oxygen stoichiometric ratio. This problem can be, in principle, solved either by using electrolytes with lower methanol or ethanol permeability or by developing new cathode electrocatalysts with both higher alcohol tolerance and higher activity for the oxygen reduction reaction than Pt. This chapter presents an overview of recent developments of platinum and non-platinum-based catalysts as methanol and ethanol-tolerant oxygen reduction materials for direct alcohol fuel cells. © Springer Science+Business Media Dordrecht 2014. All rights are reserved.
    No preview · Article · Oct 2013
  • Source
    Amanda Cristina Garcia · Edson A. Ticianelli
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · Sep 2013 · Electrochimica Acta
  • Source
    [Show abstract] [Hide abstract]
    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).
    Full-text · Article · Aug 2013 · Electrochimica Acta

27 Following View all

156 Followers View all