Pere Cabot | University of Barcelona (original) (raw)
Papers by Pere Cabot
Science of The Total Environment, Dec 1, 2020
Water Research, Feb 1, 2020
Separation and Purification Technology, 2019
International Journal of Hydrogen Energy, Aug 1, 2020
Key Engineering Materials, 1991
European Polymer Journal, Mar 1, 2006
Journal of Materials Science, 1993
Journal of The Electrochemical Society, 2005
ABSTRACT The oxidation of to water on commercial platinum catalyzed carbon-polytetrafluoroethylen... more ABSTRACT The oxidation of to water on commercial platinum catalyzed carbon-polytetrafluoroethylene gas diffusion electrode (GDE) has been studied in deoxygenated aqueous solutions with KOH concentrations in the range . The couple behaves reversibly in open circuit, closely following the Nernst equation. A semiempirical equation in agreement with a Tafel–Volmer mechanism, accounting for diffusion, adsorption, inhibition, charge transfer, and ohmic-type drop in the wetted electrode pores, has been developed to quantitatively explain the steady-state linear sweep voltammograms for the different media, temperatures, and feeding hydrogen partial pressures tested. Charge transfer is also slow at high overpotentials except for KOH. The micropolarization in the current–potential region around the reversible potential has been interpreted considering the Tafel reaction as the rate-determining step. The decay in exchange current density and the increase in activation energy both, at the reversible potential and high overpotentials, with raising KOH concentration has been ascribed to the increasing blocking and energetic effect of adsorbed hydroxyl species. The results of the activation energies suggest that the reactive Pt(110) faces are dominant in the dispersed Pt particles of the GDE.
Journal of Applied Electrochemistry, Apr 1, 1993
The potentiostatic passivation of upward-facing horizontal zinc electrodes in quiescent 0.4–4 M K... more The potentiostatic passivation of upward-facing horizontal zinc electrodes in quiescent 0.4–4 M KOH solutions has been studied according to different models and by SEM, coulometry and ICP. An initial flat maximum was found for all the potentiostatic transients except in 0.4 M KOH. The greatest part of the transients consisted in the initial maximum followed by a current plateau and
Chemischer Informationsdienst, Dec 3, 1985
Materials Science Forum, Aug 1, 1998
The surface activity of aluminium alloys in artificial sea water has been studied using electroch... more The surface activity of aluminium alloys in artificial sea water has been studied using electrochemical testing methods Electrochemical Impedance Spectroscopy (EIS), polarisation curves and electrode potential versus time measurements have been employed to study the main features of the processes taking place at the alloy/solution interface. The results obtained were discussed in terms of morphological structure and surface electrochemical behaviour correlation. The knowledge of the surface composition and the morphological structure has been performed using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDXS). The Al-Mg-Zn alloys have been prepared using metals of high purity. The methodology of preparation allows the formation of intermetallic phases which strongly influence the anodic behaviour of aluminium.
Springer eBooks, Sep 21, 2009
Here, we describe the fundamentals, laboratory experiments, and environmental applications of ind... more Here, we describe the fundamentals, laboratory experiments, and environmental applications of indirect electrooxidation methods based on H2O2 electrogeneration such as electro-Fenton, photoelectro-Fenton and peroxicoagulation for the treatment of acidic wastewaters containing toxic and recalcitrant organics. These methods are electrochemical advanced oxidation processes that can be used in divided and undivided electrolytic cells in which pollutants are oxidized by hydroxyl radical
Journal of The Electrochemical Society, 2003
ABSTRACT The behavior of the redox couple at equilibrium on a commercial uncatalyzed carbon-polyt... more ABSTRACT The behavior of the redox couple at equilibrium on a commercial uncatalyzed carbon-polytetrafluoroethylene (PTFE) oxygen-diffusion electrode, fed with partial pressures between 0.21 and 1.0 atm, has been studied by electrochemical impedance spectroscopy. Measurements have been made in the open-circuit potential using aqueous solutions with KOH concentrations in the range 1.0-6.0 mol dm−3 and concentrations up 50 mmol dm−3 at 25.0°C. Under these conditions, the system is controlled by activation, the charge-transfer resistance being much higher than ohmic, adsorption, and diffusion resistive elements. The double-layer capacities show that the wetted electroactive areas, much smaller than the total area, depend on the KOH concentration used for activation. True exchange current densities of about 1 μA cm−2 are obtained, while their apparent values are two orders of magnitude greater, since the sluggish reaction is compensated by the high electroactive area. The cathodic process is a first-order reaction with respect to the feed, and independent of and concentrations. For the anodic one, a zero order for and a first order for and are calculated. These results agree with the previously proposed mechanism for the reduction to on the same electrode from voltammetric studies. Indirect evidence on a weak adsorption of is found from the impedance diagrams. © 2002 The Electrochemical Society. All rights reserved.
Journal of Electroanalytical Chemistry, Feb 1, 2009
Journal of Electroanalytical Chemistry, Sep 1, 1997
Electrochemistry Communications, Jun 1, 2010
ABSTRACT The catalytic activity towards the oxygen reduction reaction (ORR) of a novel material c... more ABSTRACT The catalytic activity towards the oxygen reduction reaction (ORR) of a novel material consisting of clusters of Pd nanoparticles directly deposited on porous carbon paper by electroless deposition, has been investigated in sulphuric acid medium. It is shown that this new material exhibits a very high electrocatalytic activity for the ORR, compared to the commercial carbon paper-supported Pt.
Journal of Applied Electrochemistry, Feb 1, 1995
The authors of the above work do not feel that they misinterpreted pitting corrosion using polari... more The authors of the above work do not feel that they misinterpreted pitting corrosion using polarization resistance, Tafel slopes and the equilibrium potential of the A1203 • 3H20/A1 couple. In the above paper, the polarization resistance data were only determined in oxygen free solutions and under steady state conditions from micropolarization experiments in order not to affect the open circuit potential (o.c.p.). In this case, the o.c.p, was about -1.2V vs SCE and the alloys did not show pitting attack. In contrast, in aerated solutions, the corrosion potential (Ecorr)was about -0.8 V vs SCE and pitting was demonstrated. No polarization resistance data were given in this latter case. The Tafel data reported in the above paper were not obtained by the Tafel extrapolation method. They were obtained using a program which fits the experimental results to a difference of exponential terms over a small potential range near the o.c.p. This was only performed in a number of experiments simply to compare the behaviour of the alloys studied. No calculations on the corrosion rates were intended. The Tafel parameters were qualitatively interpreted according to the well known fact that greater Tafel slopes correspond to the more protective passive films. The alloys studied in the above paper contained small amounts of intermetallic compounds which were not attacked in oxygen-free solutions. Polarization resistance and Tafel data permitted the effect of such intermetallic compounds on the properties of the passive film in the absence of pitting attack to be demonstrated. When pitting occurs, such determinations are, in fact, very difficult. The basic problem is the kinetic interpretation, which can only be achieved using a suitable model. The most favourable case appears when the anodic reaction remains steady and highly localized [1]. Several laboratories including our own are developing techniques to study pitting corrosion under steady state conditions. The second question raised by L. Tomcsfinyi is that pitting (E~) and corrosion potentials can not be related with calculated thermodynamic data. However, the authors of the above paper did not perform any calculations to relate such quantities. Instead, they simply compared such potential values as is usual when representing pitting and repassivation potentials on the Pourbaix diagram in order to establish the active and passive zones [2-4]. The third question refers to the use of an excess of sulphate when determining E~. Pitting corrosion is a complicated phenomenon and several theories have been given [5]. In fact, L. Tomcsfinyi et al. [6] proved by a radiotracer technique that sulphate is adsorbed on the oxide film. They also proposed the chemical bonding of chloride at the oxide/solution interface as an initial step of heterogeneous reaction between chloride and the oxide film. However, this initial step is really a chemical adsorption. Therefore, the conclusion of L. Tomcsalayi et al. [6], i.e. that all the theories of aluminium pitting corrosion involving the abor adsorption of chloride are misleading, is not correct. The concentrations of chloride investigated by L. Tomcsfinyi et al. were in the range 10-2-10-3mol dm -3 while l moldm -3 Na2SO4 was used as a supporting electrolyte. Sulphate cannot be simply a supporting electrolyte because it presents specific adsorption and, therefore, blocks the oxide surface sites where chloride may be bonded. Painot and Augustynski [7] have shown by ESCA that chloride and sulphate penetrate into the oxide film at o.c.p. and also that the chloride content increases with respect to the sulphate content when the critical potential is approached (i.e. the chloride content of the anodic film depends on the potential). Therefore, two questions can be posed in relation to the mechanism proposed by L. Tomcsfinyi et al. If chloride simply reacts with the oxide film, why does pitting only appear from a certain critical potential? If E~ changes when sulphate is added to chloride solutions, what is the meaning of E~ when sulphate is absent. In a recent work of the authors [8] it is shown that additions of sulphate to chloride solutions shifts E~ in the positive direction, but the repassivation potential does not change significantly (the repassivation potential is much more reproducible and appears to better characterize pitting corrosion rather than E~ [9]). This cannot simply be explained by the migration transport of chloride. The role of migration transport in pit initiation is unclear because during the anodic sweep and in the conditions prior to pit initiation the anodic current is very small.
Journal of The Electrochemical Society, May 1, 1998
The current density response of H 2 -fed (1 atm) Pd foil anodes in MeOH-water mixtures has been s... more The current density response of H 2 -fed (1 atm) Pd foil anodes in MeOH-water mixtures has been studied by current vs. voltage measurements and scanning electron microscopy. The current density response of different hydrogen-diffusion anodes, based on 25 μm thick Pd foils coated on both sides with electrodeposited Pd black, has been tested for aqueous and MeOH (70% volume per volume)-water mixtures containing NH 4 Cl at concentrations near saturation. The anode current density response increased with temperature, but decreased in the presence of MeOH in the electrolyte. The best anode current density response was obtained with Pd black electrodeposited at 50°C and current densities about -15 mA cm -2 in acid (i.e., with 40 g dm -3 NH 4 Cl and set to pH 0 with HCl) with 2% PdCl 2 . In this case, quasi-stationary current densities ca. 50 mA cm -2 , with hydrogen oxidation efficiency of 100%, in MeOH-water mixtures containing 1 mol dm -3 NH 4 Cl at 20°C were obtained. A possi le mechanism of the process is discussed.
Journal of Cleaner Production, 2019
Science of The Total Environment, Dec 1, 2020
Water Research, Feb 1, 2020
Separation and Purification Technology, 2019
International Journal of Hydrogen Energy, Aug 1, 2020
Key Engineering Materials, 1991
European Polymer Journal, Mar 1, 2006
Journal of Materials Science, 1993
Journal of The Electrochemical Society, 2005
ABSTRACT The oxidation of to water on commercial platinum catalyzed carbon-polytetrafluoroethylen... more ABSTRACT The oxidation of to water on commercial platinum catalyzed carbon-polytetrafluoroethylene gas diffusion electrode (GDE) has been studied in deoxygenated aqueous solutions with KOH concentrations in the range . The couple behaves reversibly in open circuit, closely following the Nernst equation. A semiempirical equation in agreement with a Tafel–Volmer mechanism, accounting for diffusion, adsorption, inhibition, charge transfer, and ohmic-type drop in the wetted electrode pores, has been developed to quantitatively explain the steady-state linear sweep voltammograms for the different media, temperatures, and feeding hydrogen partial pressures tested. Charge transfer is also slow at high overpotentials except for KOH. The micropolarization in the current–potential region around the reversible potential has been interpreted considering the Tafel reaction as the rate-determining step. The decay in exchange current density and the increase in activation energy both, at the reversible potential and high overpotentials, with raising KOH concentration has been ascribed to the increasing blocking and energetic effect of adsorbed hydroxyl species. The results of the activation energies suggest that the reactive Pt(110) faces are dominant in the dispersed Pt particles of the GDE.
Journal of Applied Electrochemistry, Apr 1, 1993
The potentiostatic passivation of upward-facing horizontal zinc electrodes in quiescent 0.4–4 M K... more The potentiostatic passivation of upward-facing horizontal zinc electrodes in quiescent 0.4–4 M KOH solutions has been studied according to different models and by SEM, coulometry and ICP. An initial flat maximum was found for all the potentiostatic transients except in 0.4 M KOH. The greatest part of the transients consisted in the initial maximum followed by a current plateau and
Chemischer Informationsdienst, Dec 3, 1985
Materials Science Forum, Aug 1, 1998
The surface activity of aluminium alloys in artificial sea water has been studied using electroch... more The surface activity of aluminium alloys in artificial sea water has been studied using electrochemical testing methods Electrochemical Impedance Spectroscopy (EIS), polarisation curves and electrode potential versus time measurements have been employed to study the main features of the processes taking place at the alloy/solution interface. The results obtained were discussed in terms of morphological structure and surface electrochemical behaviour correlation. The knowledge of the surface composition and the morphological structure has been performed using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDXS). The Al-Mg-Zn alloys have been prepared using metals of high purity. The methodology of preparation allows the formation of intermetallic phases which strongly influence the anodic behaviour of aluminium.
Springer eBooks, Sep 21, 2009
Here, we describe the fundamentals, laboratory experiments, and environmental applications of ind... more Here, we describe the fundamentals, laboratory experiments, and environmental applications of indirect electrooxidation methods based on H2O2 electrogeneration such as electro-Fenton, photoelectro-Fenton and peroxicoagulation for the treatment of acidic wastewaters containing toxic and recalcitrant organics. These methods are electrochemical advanced oxidation processes that can be used in divided and undivided electrolytic cells in which pollutants are oxidized by hydroxyl radical
Journal of The Electrochemical Society, 2003
ABSTRACT The behavior of the redox couple at equilibrium on a commercial uncatalyzed carbon-polyt... more ABSTRACT The behavior of the redox couple at equilibrium on a commercial uncatalyzed carbon-polytetrafluoroethylene (PTFE) oxygen-diffusion electrode, fed with partial pressures between 0.21 and 1.0 atm, has been studied by electrochemical impedance spectroscopy. Measurements have been made in the open-circuit potential using aqueous solutions with KOH concentrations in the range 1.0-6.0 mol dm−3 and concentrations up 50 mmol dm−3 at 25.0°C. Under these conditions, the system is controlled by activation, the charge-transfer resistance being much higher than ohmic, adsorption, and diffusion resistive elements. The double-layer capacities show that the wetted electroactive areas, much smaller than the total area, depend on the KOH concentration used for activation. True exchange current densities of about 1 μA cm−2 are obtained, while their apparent values are two orders of magnitude greater, since the sluggish reaction is compensated by the high electroactive area. The cathodic process is a first-order reaction with respect to the feed, and independent of and concentrations. For the anodic one, a zero order for and a first order for and are calculated. These results agree with the previously proposed mechanism for the reduction to on the same electrode from voltammetric studies. Indirect evidence on a weak adsorption of is found from the impedance diagrams. © 2002 The Electrochemical Society. All rights reserved.
Journal of Electroanalytical Chemistry, Feb 1, 2009
Journal of Electroanalytical Chemistry, Sep 1, 1997
Electrochemistry Communications, Jun 1, 2010
ABSTRACT The catalytic activity towards the oxygen reduction reaction (ORR) of a novel material c... more ABSTRACT The catalytic activity towards the oxygen reduction reaction (ORR) of a novel material consisting of clusters of Pd nanoparticles directly deposited on porous carbon paper by electroless deposition, has been investigated in sulphuric acid medium. It is shown that this new material exhibits a very high electrocatalytic activity for the ORR, compared to the commercial carbon paper-supported Pt.
Journal of Applied Electrochemistry, Feb 1, 1995
The authors of the above work do not feel that they misinterpreted pitting corrosion using polari... more The authors of the above work do not feel that they misinterpreted pitting corrosion using polarization resistance, Tafel slopes and the equilibrium potential of the A1203 • 3H20/A1 couple. In the above paper, the polarization resistance data were only determined in oxygen free solutions and under steady state conditions from micropolarization experiments in order not to affect the open circuit potential (o.c.p.). In this case, the o.c.p, was about -1.2V vs SCE and the alloys did not show pitting attack. In contrast, in aerated solutions, the corrosion potential (Ecorr)was about -0.8 V vs SCE and pitting was demonstrated. No polarization resistance data were given in this latter case. The Tafel data reported in the above paper were not obtained by the Tafel extrapolation method. They were obtained using a program which fits the experimental results to a difference of exponential terms over a small potential range near the o.c.p. This was only performed in a number of experiments simply to compare the behaviour of the alloys studied. No calculations on the corrosion rates were intended. The Tafel parameters were qualitatively interpreted according to the well known fact that greater Tafel slopes correspond to the more protective passive films. The alloys studied in the above paper contained small amounts of intermetallic compounds which were not attacked in oxygen-free solutions. Polarization resistance and Tafel data permitted the effect of such intermetallic compounds on the properties of the passive film in the absence of pitting attack to be demonstrated. When pitting occurs, such determinations are, in fact, very difficult. The basic problem is the kinetic interpretation, which can only be achieved using a suitable model. The most favourable case appears when the anodic reaction remains steady and highly localized [1]. Several laboratories including our own are developing techniques to study pitting corrosion under steady state conditions. The second question raised by L. Tomcsfinyi is that pitting (E~) and corrosion potentials can not be related with calculated thermodynamic data. However, the authors of the above paper did not perform any calculations to relate such quantities. Instead, they simply compared such potential values as is usual when representing pitting and repassivation potentials on the Pourbaix diagram in order to establish the active and passive zones [2-4]. The third question refers to the use of an excess of sulphate when determining E~. Pitting corrosion is a complicated phenomenon and several theories have been given [5]. In fact, L. Tomcsfinyi et al. [6] proved by a radiotracer technique that sulphate is adsorbed on the oxide film. They also proposed the chemical bonding of chloride at the oxide/solution interface as an initial step of heterogeneous reaction between chloride and the oxide film. However, this initial step is really a chemical adsorption. Therefore, the conclusion of L. Tomcsalayi et al. [6], i.e. that all the theories of aluminium pitting corrosion involving the abor adsorption of chloride are misleading, is not correct. The concentrations of chloride investigated by L. Tomcsfinyi et al. were in the range 10-2-10-3mol dm -3 while l moldm -3 Na2SO4 was used as a supporting electrolyte. Sulphate cannot be simply a supporting electrolyte because it presents specific adsorption and, therefore, blocks the oxide surface sites where chloride may be bonded. Painot and Augustynski [7] have shown by ESCA that chloride and sulphate penetrate into the oxide film at o.c.p. and also that the chloride content increases with respect to the sulphate content when the critical potential is approached (i.e. the chloride content of the anodic film depends on the potential). Therefore, two questions can be posed in relation to the mechanism proposed by L. Tomcsfinyi et al. If chloride simply reacts with the oxide film, why does pitting only appear from a certain critical potential? If E~ changes when sulphate is added to chloride solutions, what is the meaning of E~ when sulphate is absent. In a recent work of the authors [8] it is shown that additions of sulphate to chloride solutions shifts E~ in the positive direction, but the repassivation potential does not change significantly (the repassivation potential is much more reproducible and appears to better characterize pitting corrosion rather than E~ [9]). This cannot simply be explained by the migration transport of chloride. The role of migration transport in pit initiation is unclear because during the anodic sweep and in the conditions prior to pit initiation the anodic current is very small.
Journal of The Electrochemical Society, May 1, 1998
The current density response of H 2 -fed (1 atm) Pd foil anodes in MeOH-water mixtures has been s... more The current density response of H 2 -fed (1 atm) Pd foil anodes in MeOH-water mixtures has been studied by current vs. voltage measurements and scanning electron microscopy. The current density response of different hydrogen-diffusion anodes, based on 25 μm thick Pd foils coated on both sides with electrodeposited Pd black, has been tested for aqueous and MeOH (70% volume per volume)-water mixtures containing NH 4 Cl at concentrations near saturation. The anode current density response increased with temperature, but decreased in the presence of MeOH in the electrolyte. The best anode current density response was obtained with Pd black electrodeposited at 50°C and current densities about -15 mA cm -2 in acid (i.e., with 40 g dm -3 NH 4 Cl and set to pH 0 with HCl) with 2% PdCl 2 . In this case, quasi-stationary current densities ca. 50 mA cm -2 , with hydrogen oxidation efficiency of 100%, in MeOH-water mixtures containing 1 mol dm -3 NH 4 Cl at 20°C were obtained. A possi le mechanism of the process is discussed.
Journal of Cleaner Production, 2019