Cinzia Cristiani

Politecnico di Milano, Milano, Lombardy, Italy

Are you Cinzia Cristiani?

Claim your profile

Publications (64)159.06 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper the effect of the addition of carboxymethylcellulose (CMC) to microporous layers (MPLs) formulation is reported and the rheological, morphological and electrical properties of the so-obtained MPLs are assessed. Two different PTFE/carbon black ratios are considered, with and without CMC in the ink formulation. CMC addition results in a better homogeneity and stability of the inks. Moreover, the presence of CMC leads to a better shear thinning behaviour and to a general increase in viscosity that makes these slurries more appropriate for coating deposition via doctor blade technique. The presence of CMC in MPL formulation also affects the electrochemical performances in terms of I–V curves and impedance spectra. CMC-containing MPLs show the best performances in terms of generated power at high temperature (80 °C) and low cathodic relative humidity (RH 60 %). Ohmic resistances too, in presence of CMC, are lower than those exhibited by CMC-free MPLs.
    Fuel Cells 04/2015; DOI:10.1002/fuce.201400054 · 1.55 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: press as: Pelosato R, et al. Electrical characterization of co-precipitated LaBaCo 2 O 5+δ and YBaCo 2 O 5+δ oxides. J Eur Ceram Soc (2014), Abstract REBaCo 2 O 5+δ layered perovskite oxides (RE = Rare Earth) are promising cathodes for IT-SOFCs. In this work, a simple co-precipitation synthesis in aqueous medium was applied to prepare LaBaCo 2 O 5+δ (LBC) and YBaCo 2 O 5+δ (YBC) cathodes. The chemical and electrochemical properties of both materials were characterized via XRD, SEM, TPO, TG–DTA, 4-probe conductivity measurement, and EIS tests on symmetric cells. The coprecipitation synthesis revealed a promising preparation route: the measured ASR values of both materials were well comparable with the literature ones. A kinetic investigation of the O 2 reduction process was performed on LBC (600–800 • C, 5–100% O 2 , v/v), whose results were analyzed with equivalent circuits. The main steps were identified (oxygen diffusion and charge transfer at high frequency, O 2 chemisorption at medium frequency), and their activation energy and reaction order were quantified. Aging tests (500 h time on stream, 500–800 • C) revealed quick deactivation for YBC and good stability for LBC.
    Journal of the European Ceramic Society 12/2014; DOI:10.1016/j.jeurceramsoc.2014.07.005 · 2.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Coating is the most widely used technique for the preparation of structured catalysts. This paper reviews the main methods reported in the open literature for depositing catalytic layers onto metallic substrates, specifically focusing on the coating of metallic honeycomb monoliths and open-cell foams. All the relevant steps, including substrate pre-treatments, means for catalytic activation and thermal treatments, are discussed.
    08/2014; 4(9). DOI:10.1039/C4CY00179F
  • [Show abstract] [Hide abstract]
    ABSTRACT: Gas diffusion medium (GDM) is a crucial carbon-based component for water management in polymer electrolyte membrane fuel cells (PEMFCs). GDM consists of a macro-porous substrate, which is usually a carbon cloth or carbon paper, coated with a thin micro-porous layer (MPL). Traditionally, PTFE is used as hydrophobic agent and binder. In this work, three different GDMs were prepared using fluorinated polymers (polytetrafluoroethylene-co-hexafluoro-propylene (FEP), polytetrafluoroethylene-co-perfluoroalcoxy vinyl ether (PFA) and a fluorinated polyurethane based on perfluoropolyether blocks (PFPE)) in order to replace conventional PTFE as hydrophobic agent, which was used as reference. Inks composition and rheological behaviour were fixed in order to apply the blade coating technique for MPL deposition. These polymers allowed to decrease temperature during thermal treatments with respect to the one necessary for treating PTFE-based MPLs. Moreover, superhydrophobic layers were obtained for all the samples and the final electrical performances of the whole fuel cell system were improved with respect to the ones reached with PTFE-based samples. In particular, FEP allowed to reduce significantly mass transfer resistances in the operating conditions of the fuel cell.
    Progress in Organic Coatings 07/2014; DOI:10.1016/j.porgcoat.2014.05.028 · 2.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A 2D isothermal axisymmetric model of an anode-supported solid oxide fuel cell has been developed. The model, which is based on finite element approach, comprises electronic and ionic charge balance, Butler–Volmer charge transfer kinetic, flow distribution and gas phase mass balance in both channels and porous electrodes. The model has been validated using available experimental data coming from a single anode-supported cell comprising Ni–YSZ/YSZ/LSM–YSZ as anode, electrolyte and cathode, respectively. Hydrogen and steam were used as fuel inlet and air as an oxidant. The validation has been carried out at 1 atm, 1,500 ml min–1 air flow rate and three different operating conditions of temperature and fuel flow rate: 1,073 K and 400 ml min–1, 1,073 K and 500 ml min–1, and 1,003 K and 400 ml min–1. The polarization and power density versus current density curves show a good agreement with the experimental data. A parametric analysis has been carried out to highlight which parameters have main effect on the overall cell performance as measured by polarization curve, especially focusing on the influence of two geometrical characteristics, temperature and some effective material properties.
    Fuel Cells 04/2014; 14(2). DOI:10.1002/fuce.201300235 · 1.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Microporous layers (MPLs) obtained from inks containing three fluorinated polymers (perfluoroalcoxy, fluorinated ethylene propylene and a fluorinated polyurethane based on perfluoropolyether blocks) replacing conventional PTFE were prepared. Inks composition and rheological behaviour were fixed in order to apply the blade coating technique for MPL deposition. Superhydrophobic layers were obtained since contact angles higher than 150 degrees were measured. The samples, tested in a single fuel cell at lab scale, at 60 degrees C and different relative humidity (RH 80/100 and 80/60, hydrogen/air) evidenced that new polymers are able to improve electrical performances reaching maximum power density values higher than those showed by conventional MPLs based fuel cells. Electrochemical impedance spectroscopy (EIS) was also carried out on the running cell using a Frequency Response Analyzer to assess the different dissipation phenomena and related losses. Copyright
    International Journal of Hydrogen Energy 03/2014; 39(10):5350-5357. DOI:10.1016/j.ijhydene.2013.12.199 · 2.93 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This work presents the application of FT IR spectroscopy to study the thermal evolution of PEG-based nanocomposites prepared using montmorillonite STx intercalated with polyethylene-oxides PEG 1500 and PEG 4000 and polyethylene oxide Brij. The effect of different polymer molecular weight and polymer loadings has been evaluated by means of diagnostic mid-IR bands. PEG fragmentation through the cleavage of the C-O bond appears to be the main reaction step, leading to the formation of short chain carbonyl adsorbed species (such as acetaldehyde), alcohols (ethanol and methanol) and, to a lesser extent, esters species, characterized by the frequency of the carbonyl stretching band. The detection of carbonyl band evidenced the formation of partial oxidation products as first step of the thermal degradation. Increasing polymer loadings, as well as increasing polymer molecular weight leads to lower temperature of formation of the first oxidation products. No clear indication of the effect of the chemical nature for the intercalated polymers can be obtained. BRIJ thermal decomposition seems to be mainly driven by the PEG-like moiety chemistry. CH stretching bands detected at 450-500 °C for the samples intercalated with PEG samples indicated the formation of residual organic compounds resisting oxidation, possibly char species preserved from further oxidation by the interlayer galleries.
    Vibrational Spectroscopy 03/2014; 71. DOI:10.1016/j.vibspec.2013.12.010 · 1.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A very simple, cost-effective, chloride- and alkali-free, carbonate co-precipitation synthesis in aqueous medium was applied in the preparation of perovskite-type lanthanum manganese oxide-based powders, i.e. La0.70Sr0.30MnO3−δ (LSM) and La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCrM). The precursors so obtained yielded nano-structured perovskite oxides when treated at 900°C and 800°C, respectively. The measured BET surface areas were in the low-end range for high temperature oxides (4 m2 g−1 and 10 m2 g−1) but the X-ray crystallite size was as low as 50 nm for LSCrM and 90 nm for LSM.
    Chemical Papers- Slovak Academy of Sciences 05/2013; 67(5). DOI:10.2478/s11696-013-0306-z · 1.19 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A series of four compounds (LaMnO3, La0.70Sr0.30MnO3−δ, La0.80Sr0.20FeO3−δ and La0.75Sr0.25Cr0.50Mn0.50O3−δ) of interest as electrode materials in intermediate temperature solid oxide fuel cells have been prepared using a carbonate co-precipitation route in aqueous medium. LaMnO3, La0.70Sr0.30MnO3−δ, and La0.75Sr0.25Cr0.50Mn0.50O3−δ have been obtained as a pure phase, while La0.80Sr0.20FeO3−δ retained an impurity phase; fine microstructures with sub-micron sized particles can be obtained in all cases at the proper calcinations temperature, except for LaMnO3. The precipitation yield of the single metal ions have been experimentally determined in the mother liquors and in the final powders; the results have been evaluated also in comparison with expected yields calculated from thermodynamics of the precipitation process using the software Medusa. pH higher than 7.5 are suggested to avoid ion losses for all cations. Structural and microstructural properties and TPO/TPR behaviour suggest that materials prepared via co-precipitation, especially LSCM, could be suited as electrode materials in solid oxide fuel cells.
    International Journal of Hydrogen Energy 01/2013; 38(1):480-491. DOI:10.1016/j.ijhydene.2012.09.063 · 2.93 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Preparation of active washcoats of Ni/MgAl2O4 steam-reforming catalysts on FeCrAlloy foams is reported in this work. The MgAl2O4 powdered support was prepared via co-precipitation method, and Ni/MgAl2O4 was obtained via dry impregnation of 10% (w/w) of Ni. After full characterization of the powders, the deposition of the catalyst over the foams was performed by percolation followed by air-blowing (percolation-blowing). The resulting washcoat layers were quite homogeneous, uniform, and well adherent to the metallic support. Prototype catalytic foam samples, tested at the lab-scale, were found to be active in the steam reforming process.
    Catalysis Today 12/2012; DOI:10.1016/j.cattod.2012.09.003 · 3.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Formulations of carbon-based inks for doctor blade applications were considered and the use of Carboxymethylcellulose (CMC) as rheology modifier and suspension stabilizer was proposed. Rheological measurement evidenced that CMC addition guarantees a good dispersion of the carbon powder which results in a higher stability of the ink. The electrical performances of Gas Diffusion Layer (GDL) coated with Micro-Porous Layers (MPLs) prepared with and without CMC were compared. A single PEMFC was used to assess the properties of these GDLs: electrochemical performances were tested in terms of I–V curves and of AC Electrochemical Impedance Spectroscopy (EIS) of the running cell. CMC-containing GDLs showed improved performances when the cell was operated at 80 °C and RH 80–60. Analysis of the EIS spectra demonstrated that, at high Current Density (CD), the CMC-based GDLs suffer for water management. Such a behavior was ascribed to a hydrophilic character of the GDL due to residual amounts of CMC in MPL coating.
    Solid State Ionics 05/2012; 216:73–77. DOI:10.1016/j.ssi.2012.03.030 · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Two polyethylene-glycols (PEG), having different molecular weight (i.e. PEG 1500 and PEG 4000) were intercalated inside the interlayer space of a STx montmorillonite. The microstructure of the intercalated clay mineral was investigated by thermogravimetry (TG) and in situ high temperature-XRD, in order to assess the evolution of the interlayer space upon temperature. Data were collected over a temperature range of 25–1000 °C and 25–850 °C for TG and thermo-XRD, respectively. Decomposition of the intercalated polymers was very different compared to the one of the pure surfactants, as detected by TG and FT IR spectroscopy. In situ high temperature-XRD data showed the formation of a high-temperature phase, detected at 250 °C, independently from the molecular weight of the PEG intercalated. This phase showed to be stable when the temperature was decreased to 25 °C and was raised again to 250 °C. An irregularly interstratified phase was observed when the modified clay minerals were heated at 200 °C.
    Applied Clay Science 05/2012; s 59–60:140–147. DOI:10.1016/j.clay.2012.02.015 · 2.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work we investigate the effect of ceria and other rare earths (La, Pr, Tb) on Pd–PdO transformation, which is strongly related to the catalytic activity of Pd-based catalysts for the combustion of methane at high temperature. Also the behavior of Pd on ZrO2 and on yttria-stabilized zirconia is considered for comparison. The catalysts are characterized by XRD and BET surface area measurements. Pd–PdO transformation is studied by means of temperature programmed oxidation measurements and thermogravimetric analysis. Temperature programmed combustion experiments have been carried out in order to compare catalytic activity of different catalysts. The results show that rare earth oxides promote the onset of Pd re-oxidation upon cooling, that for ceria doped sample is reflected in an improvement in the catalytic activity.
    Catalysis Today 01/2012; 180(1):124. DOI:10.1016/j.cattod.2011.03.021 · 3.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present work, preliminary results of different hydrophobic surface treatments for gas diffusion layer (GDL) for PEM fuel cells are presented. This hydrophobic coating consists of new perfluoropolyether (PFPE) derivatives, in comparison to standard polytetrafluoroethylene (PTFE) dispersions. Experimental conditions for an efficient coating of fluoropolymers onto carbon clothes were explored by wet chemical methods.The GDLs obtained were tested in a single fuel cell at the lab scale. The cell testing was run at two temperatures (60°C and 80°C) with a relative humidity (RH) of the feeding gases of 80/100%, hydrogen/air respectively.The new PFPE coatings measurably improve the cell performances, and this effect is more evident at 60°C with respect to 80°C.
    Journal of Power Sources 09/2011; 196(18):7645-7648. DOI:10.1016/j.jpowsour.2011.04.039 · 5.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The intercalation of organic polymers molecules (i.e., PEGs and BRIJ) into a standard Ca-montmorillonite has been studied by XRD, TG, and IR spectroscopy. The polymer intercalation is confirmed by the increasing of the d(001) in XRD spectra as well as by the complex multisteps thermal decomposition behavior of the organo-clay materials. Mid-IR and diffuse reflectance near-IR spectra of the intercalated materials show the polymer diagnostic bands (CH stretching and deformation mode), shifted or changed in shape by the interaction with the clay matrix. Both PEG 1500 and PEG 4000 based materials are likely intercalated in an extended configuration, similar to the amorphous polymer form. BRIJ intercalated polymer spectra suggest the disordered conformation of the alkilic chain in a prevailing "gauche", poorly packed, conformation. Host montmorillonite IR bands, mainly OH and water stretching and deformation fundamentals, combination, and overtone bands, are reduced in intensity by polymer intercalation, pointing out an interaction, likely through H-bonding and/or a possible substitution of cations hydration water molecules.
    The Journal of Physical Chemistry A 06/2011; 115(26):7484-93. DOI:10.1021/jp200845e · 2.78 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A simple and inexpensive co-precipitation route in aqueous medium is proposed to prepare La0.8Sr0.2Ga0.8Mg02O3−δ ionic conductor (LSGM). Different synthetic procedures and operating parameters (i.e. nature and amount of the precipitating agents, HNO3 addition and temperature) have been evaluated in order to underline their influence on the composition and microstructure of the final phase. Intermediate and final products were characterized by Thermal-Gravimetry, IR-spectroscopy, X-ray Powder Diffraction, Rietveld analysis and Scanning Electron Microscopy. The electrical properties were measured by Impedance Spectroscopy in the temperature range 250–800 °C. Slight variations of the synthetic procedure (such as precipitating agent amount or no HNO3 addition) have a considerable and detrimental effect on the ions losses and the subsequent achievement of the final phase. The use NH4OH as an alternative precipitating agent is dramatically disadvantageous. Ions losses during precipitation must be controlled (i) to avoid understoichiometry in the LSGM phase and (ii) to prevent the formation of large amounts of secondary phases. In fact, both affect the total electrical conductivity.The use of large excess of (NH4)2CO3 precipitating agent and the addition of HNO3 lead to the best material characterized by a rhombohedral structure, small amount of side phases, a relative density of 98% and a total conductivity of 6.44 × 10−2 S cm−1 at 800 °C and 1.13 × 10−2 S cm−1 at 600 °C.
    Journal of Power Sources 12/2010; 195(24):8116–8123. DOI:10.1016/j.jpowsour.2010.07.046 · 5.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present research investigated the intercalation of three different polymers, namely polyethylene-glycol (PEG) 1500 and 4000, and BRIJ78 into STx-1 montmorillonite. Samples of modified montmorillonite were prepared starting from different initial concentrations in solution (C0) ranging from 20 to 180 mM. The basal spacing of the modified clay minerals was related to the amounts of polymer intercalated, estimated by COD (Chemical Oxygen Demand) analysis of the residual amounts in solution. The correlation between the basal spacings of the modified montmorillonites and the amounts of polymers intercalated allowed properly modulating the microstructural characteristics of organo-clay minerals prepared with polymers.Research Highlights►Quantification of intercalated PEOs and BRIJ78 in montmorillonite by COD. ►Use of monomeric units to compare intercalation of PEOs with different molar mass. ►Correlation between d001 and intercalated PEOs. ►A priori” modulation of the interlayer-space size.
    Applied Clay Science 10/2010; 50(2):266-270. DOI:10.1016/j.clay.2010.08.009 · 2.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A multi-wall carbon nanotubes (MWCNTs)-based gas diffusion medium (GDM) was prepared, where carbon black was partially substituted by carbon nanotube (CNT) in the formulation of the micro-porous layer (MPL). A rheological analysis of the ink used to coat the gas diffusion layer (GDL) was previously performed to correlate viscosities with the slurry composition. Shear thinning inks with viscosity of 0.4 (Pa s–1) were obtained for a composition containing 10 wt.-% of CNT and 12 wt.-% of fluorinated polymer. Using the doctor-blade technique, a coating thickness of about 100–150 μm was obtained.Moreover, electrochemical performance of a single cell assembled with the CNT-based GDM was compared with that obtained with a sample without CNTs. In order to better understand the role of CNTs, electrochemical impedance spectroscopy (EIS) of the running fuel cell (FC) was also performed. As a result, it was found that the addition of CNTs sensibly improves single cell performances.
    Fuel Cells 04/2010; 10(2):270 - 277. DOI:10.1002/fuce.200900126 · 1.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of the present research was to investigate the intercalation of three different polymer-based surfactants, namely polyethylene-glycol 1500 and 4000 (PEG 1500 and PEG 4000) and polyethylene-oxide (BRIJ 78), inside the interlayer of STx-1 montmorillonite. The effect of three parameters, such as time (30, 60, 90min), temperature (30 and 60°C) and initial concentrations in solution (45, 90, and 180mM) was studied. A full microstructural characterization of the synthesized organoclays by XRD, FT-IR, and TG-DTA was performed. The quantification of polymer intercalated was estimated by COD (Chemical Oxygen Demand) analysis of the residual amount in solution.The intercalation was successful, as showed by the basal expansions detected by XRD, and confirmed by FT-IR, showing the typical C–H-stretching bands in the spectra of the synthesized clays. TG-DTA was not a reliable technique for the quantification of polymer intercalated, while COD correctly quantified such amounts.The role of temperature and time appeared to be uninfluent for intercalating the polymer inside the interlayer of STx-1 montmorillonite, while the driving parameter ruling the amount of intercalated polymer was the initial concentration in solution.
    Applied Clay Science 03/2010; 48(1):97-102. DOI:10.1016/j.clay.2009.11.015 · 2.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new method to deposit active washcoats of Ni/MgAl2O4 steam-reforming catalysts over FeCrAlloy foams is reported in this work. The MgAl2O4 powdered support was prepared via a co-precipitation method, and Ni was dry-impregnated on it. The deposition of the catalyst over the foams was performed by dip-coating followed by air-blowing (dip-blowing). The resulting washcoat layers were quite homogeneous and uniform, and well adherent to the metallic support. Prototype catalyst samples, tested at the lab-scale, were found to be active and selective in the steam reforming process.
    Studies in surface science and catalysis 01/2010; 175:653-656. DOI:10.1016/S0167-2991(10)75129-6

Publication Stats

1k Citations
159.06 Total Impact Points

Institutions

  • 1995–2014
    • Politecnico di Milano
      • • Department of Energy
      • • Department of Chemistry, Materials and Chemical Engineering "Giulio Natta"
      Milano, Lombardy, Italy
    • Università degli Studi di Genova
      Genova, Liguria, Italy
  • 2003
    • CMIC
      Cranbury, New Jersey, United States
  • 2001
    • Cancer Immunology and Immunotherapy Center
      Athínai, Attica, Greece