The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Radenka Maric - One of the best experts on this subject based on the ideXlab platform.

  • Strategies to mitigate Pt dissolution in low Pt loading proton exchange membrane fuel cell: I. A gradient Pt particle size design
    Electrochimica Acta, 2017
    Co-Authors: Haoran Yu, Andrea Baricci, Andrea Bisello, Andrea Casalegno, L. Guétaz, Leonard Bonville, Radenka Maric
    Abstract:

    The catalyst durability at low Pt loading remains a barrier for industrial commercialization of the proton exchange membrane fuel cell. Degradation of low loaded Pt catalyst not only reduced the electrochemical surface area but also revealed a Pt Depletion Zone adjacent to the cathode/membrane interface where about 80% of the Pt was lost due to dissolution and migration into the membrane. We hypothesized that the Pt degradation can be mitigated using a gradient cathode design without sacrificing the initial fuel cell performance. With a focus on the mitigation, the first of two companion papers focuses on the Type I cathode with larger Pt particles (5 nm average size) near the cathode/membrane interface. In the second of these two papers, the Type II cathode with higher Pt loading (60 wt.% Pt on carbon) near the cathode membrane interface will be investigated. The catalyst coated membranes with gradient cathode were fabricated by reactive spray deposition technology with low Pt loading of 0.05 mg cm−2on the anode and 0.1 mg cm−2on the cathode. The DOE defined accelerated stress test was performed by imposing a triangular wave potential cycling from 0.6 V to 1.0 V for 30,000 cycles at 50 mV s−1scan rate. Results of accelerated stress test showed that the loss of electrochemical surface area and PEMFC performance were reduced for the Type I cathode compared to the control cathodes that consisted of 2 nm averaged Pt particle size only. Microscopy analysis suggested two possible mechanisms for this durability improvement: 1) the reduction of the amount of Pt lost due to Pt dissolution, and 2) the preservation of Pt particles at the cathode/membrane interface. Comparison with the control cathode showed that the loss of Pt near the cathode/membrane interfaced were reduced from 80% to 40% and the overall Pt loss of the cathode were reduced from 30% to 15%.

  • Strategies to mitigate Pt dissolution in low Pt loading proton exchange membrane fuel cell: II. A gradient Pt loading design
    Electrochimica Acta, 2017
    Co-Authors: Haoran Yu, Andrea Baricci, Andrea Casalegno, L. Guétaz, Leonard Bonville, Radenka Maric
    Abstract:

    In the second companion paper on low Pt-loaded gradient cathode, the degradation of Type II cathode with higher Pt loading (60 wt%) near the cathode/membrane interface was studied and compared to a control cathode with uniform Pt loading (40 wt%). All catalyst coated membranes were deposited through reactive spray deposition technology with average Pt particle size of 2 nm and Pt loadings of 0.05 mg cm−2and 0.1 mg cm−2on anode and cathode, respectively. The Type II cathode showed improved fuel cell performance at beginning-of-test (BOT) due to higher Pt utilization benefited from high Pt loading close to the membrane. Although the loss of electrochemical surface area for the Type II cathode was ∼80%, similar to that of the control cathode, the end-of-test performance (EOT) was improved by 50–100 mV, which can be attributed to the reduction of Pt loss in the Pt Depletion Zone (from 80% to 60%) as well as from 30% to 18% for the entire cathode. A comparison between Type I and Type II cathode was made in terms of Pt retention and particle size distribution. Type II cathode turned out to be more effective than Type I cathode as a result of being able to maintain a higher percentage of smaller particles (

Haoran Yu - One of the best experts on this subject based on the ideXlab platform.

  • Strategies to mitigate Pt dissolution in low Pt loading proton exchange membrane fuel cell: I. A gradient Pt particle size design
    Electrochimica Acta, 2017
    Co-Authors: Haoran Yu, Andrea Baricci, Andrea Bisello, Andrea Casalegno, L. Guétaz, Leonard Bonville, Radenka Maric
    Abstract:

    The catalyst durability at low Pt loading remains a barrier for industrial commercialization of the proton exchange membrane fuel cell. Degradation of low loaded Pt catalyst not only reduced the electrochemical surface area but also revealed a Pt Depletion Zone adjacent to the cathode/membrane interface where about 80% of the Pt was lost due to dissolution and migration into the membrane. We hypothesized that the Pt degradation can be mitigated using a gradient cathode design without sacrificing the initial fuel cell performance. With a focus on the mitigation, the first of two companion papers focuses on the Type I cathode with larger Pt particles (5 nm average size) near the cathode/membrane interface. In the second of these two papers, the Type II cathode with higher Pt loading (60 wt.% Pt on carbon) near the cathode membrane interface will be investigated. The catalyst coated membranes with gradient cathode were fabricated by reactive spray deposition technology with low Pt loading of 0.05 mg cm−2on the anode and 0.1 mg cm−2on the cathode. The DOE defined accelerated stress test was performed by imposing a triangular wave potential cycling from 0.6 V to 1.0 V for 30,000 cycles at 50 mV s−1scan rate. Results of accelerated stress test showed that the loss of electrochemical surface area and PEMFC performance were reduced for the Type I cathode compared to the control cathodes that consisted of 2 nm averaged Pt particle size only. Microscopy analysis suggested two possible mechanisms for this durability improvement: 1) the reduction of the amount of Pt lost due to Pt dissolution, and 2) the preservation of Pt particles at the cathode/membrane interface. Comparison with the control cathode showed that the loss of Pt near the cathode/membrane interfaced were reduced from 80% to 40% and the overall Pt loss of the cathode were reduced from 30% to 15%.

  • Strategies to mitigate Pt dissolution in low Pt loading proton exchange membrane fuel cell: II. A gradient Pt loading design
    Electrochimica Acta, 2017
    Co-Authors: Haoran Yu, Andrea Baricci, Andrea Casalegno, L. Guétaz, Leonard Bonville, Radenka Maric
    Abstract:

    In the second companion paper on low Pt-loaded gradient cathode, the degradation of Type II cathode with higher Pt loading (60 wt%) near the cathode/membrane interface was studied and compared to a control cathode with uniform Pt loading (40 wt%). All catalyst coated membranes were deposited through reactive spray deposition technology with average Pt particle size of 2 nm and Pt loadings of 0.05 mg cm−2and 0.1 mg cm−2on anode and cathode, respectively. The Type II cathode showed improved fuel cell performance at beginning-of-test (BOT) due to higher Pt utilization benefited from high Pt loading close to the membrane. Although the loss of electrochemical surface area for the Type II cathode was ∼80%, similar to that of the control cathode, the end-of-test performance (EOT) was improved by 50–100 mV, which can be attributed to the reduction of Pt loss in the Pt Depletion Zone (from 80% to 60%) as well as from 30% to 18% for the entire cathode. A comparison between Type I and Type II cathode was made in terms of Pt retention and particle size distribution. Type II cathode turned out to be more effective than Type I cathode as a result of being able to maintain a higher percentage of smaller particles (

Panos Argyrakis - One of the best experts on this subject based on the ideXlab platform.

  • Dimensional Crossover in the Growth of Depletion Zone in a Rectangular Capillary: Experiments and Monte Carlo Simulations
    MRS Proceedings, 2020
    Co-Authors: Sung Hyun Park, Hailin Peng, Panos Argyrakis, Haim Taitelbaum, Raoul Kopelman
    Abstract:

    ABSTRACTThe diffusion-limited kinetics of the growth of Depletion Zone around a static point trap in a thin, long stripe geometry was studied using a laser photobleaching experiment of fluorescein dye inside a rectangular capillary. The dynamics of the Depletion Zone was monitored by the θ-distance, defined as the distance from the trap to the point where the reactant concentration has been depleted to the specific fraction of its initial bulk value. A dimensional crossover from two dimensions to one dimension, due to the finite width of the reaction Zone, was observed. The crossover seems to occur for all θ values concurrently when the Depletion Zone touches the boundary for the first time, suggesting that the boundary information spreads faster than diffusion. Monte Carlo simulations were performed to support the experimental results. The crossover time (τc) is found to scale with the width (L) of the rectangular reaction Zone as τc ∼ L2, as expected from the Einstein's diffusion law.

  • absence of Depletion Zone effects for the trapping reaction in complex networks
    Physical Review E, 2009
    Co-Authors: Aristotelis Kittas, Panos Argyrakis
    Abstract:

    In the present work we examine in detail the formation of a Depletion Zone in the trapping reaction in networks, with a single perfect trap. We monitor the particle density $\ensuremath{\rho}(r)$ with respect to the distance $r$ from the trap. We show using Monte Carlo simulations that the Depletion Zone is absent in regular, Erdos-Renyi (ER), and scale-free (SF) networks. The density profiles show significant differences for these cases. The particles are homogeneously distributed in regular and ER networks with the Depletion effect appearing in very sparse ER networks. In SF networks we reveal the important role of the hubs, which due to their high random walk centrality are critical in the trapping reaction. In addition, the degree distribution plays a significant role in the distribution of the particles recovering the Depletion Zone formation for high $\ensuremath{\gamma}$ values. The mean connectivity of the network is found to play a significant role in both ER and SF networks.

  • Absence of Depletion Zone effects for the trapping reaction in complex networks.
    Physical review. E Statistical nonlinear and soft matter physics, 2009
    Co-Authors: Aristotelis Kittas, Panos Argyrakis
    Abstract:

    In the present work we examine in detail the formation of a Depletion Zone in the trapping reaction in networks, with a single perfect trap. We monitor the particle density rho(r) with respect to the distance r from the trap. We show using Monte Carlo simulations that the Depletion Zone is absent in regular, Erdos-Renyi (ER), and scale-free (SF) networks. The density profiles show significant differences for these cases. The particles are homogeneously distributed in regular and ER networks with the Depletion effect appearing in very sparse ER networks. In SF networks we reveal the important role of the hubs, which due to their high random walk centrality are critical in the trapping reaction. In addition, the degree distribution plays a significant role in the distribution of the particles recovering the Depletion Zone formation for high gamma values. The mean connectivity of the network is found to play a significant role in both ER and SF networks.

  • Dynamics of the Depletion Zone at a finite-sized imperfect trap in two dimensions: photobleaching experiments and simulations.
    Physical Review E, 2003
    Co-Authors: Hailin Peng, Sung Hyun Park, Panos Argyrakis, Haim Taitelbaum, Raoul Kopelman
    Abstract:

    The kinetics of the growth of Depletion Zones around a static trap in an effective two-dimensional geometry were studied experimentally with photobleaching of fluorescein dye by a focused laser beam. The phototrap served as an imperfect trap with a finite size. The growth of the Depletion Zone was monitored by the theta distance, defined as the distance from the trap to the point where the concentration of the reactants reaches a given arbitrary fraction theta (0

  • Anomalous growth of the Depletion Zone in the photobleaching trapping reaction.
    Physical review. E Statistical nonlinear and soft matter physics, 2003
    Co-Authors: Sung Hyun Park, Hailin Peng, Raoul Kopelman, Panos Argyrakis, Haim Taitelbaum
    Abstract:

    We study the anomalous growth of the Depletion Zone at a single trap, as observed in a photobleaching trapping reaction in confined geometry. We provide experimental evidence for a nonuniversal growth of this Depletion. We also find an early-time behavior of the Depletion Zone, owing to the finite size of the trap. Various laser powers are used in order to study the effects of trapping strength, interpreted theoretically in terms of an imperfect trap. The results are supported by numerical calculations. Comparison with other trapping reactions provides insight into finite-size traps.

L. Guétaz - One of the best experts on this subject based on the ideXlab platform.

  • Strategies to mitigate Pt dissolution in low Pt loading proton exchange membrane fuel cell: I. A gradient Pt particle size design
    Electrochimica Acta, 2017
    Co-Authors: Haoran Yu, Andrea Baricci, Andrea Bisello, Andrea Casalegno, L. Guétaz, Leonard Bonville, Radenka Maric
    Abstract:

    The catalyst durability at low Pt loading remains a barrier for industrial commercialization of the proton exchange membrane fuel cell. Degradation of low loaded Pt catalyst not only reduced the electrochemical surface area but also revealed a Pt Depletion Zone adjacent to the cathode/membrane interface where about 80% of the Pt was lost due to dissolution and migration into the membrane. We hypothesized that the Pt degradation can be mitigated using a gradient cathode design without sacrificing the initial fuel cell performance. With a focus on the mitigation, the first of two companion papers focuses on the Type I cathode with larger Pt particles (5 nm average size) near the cathode/membrane interface. In the second of these two papers, the Type II cathode with higher Pt loading (60 wt.% Pt on carbon) near the cathode membrane interface will be investigated. The catalyst coated membranes with gradient cathode were fabricated by reactive spray deposition technology with low Pt loading of 0.05 mg cm−2on the anode and 0.1 mg cm−2on the cathode. The DOE defined accelerated stress test was performed by imposing a triangular wave potential cycling from 0.6 V to 1.0 V for 30,000 cycles at 50 mV s−1scan rate. Results of accelerated stress test showed that the loss of electrochemical surface area and PEMFC performance were reduced for the Type I cathode compared to the control cathodes that consisted of 2 nm averaged Pt particle size only. Microscopy analysis suggested two possible mechanisms for this durability improvement: 1) the reduction of the amount of Pt lost due to Pt dissolution, and 2) the preservation of Pt particles at the cathode/membrane interface. Comparison with the control cathode showed that the loss of Pt near the cathode/membrane interfaced were reduced from 80% to 40% and the overall Pt loss of the cathode were reduced from 30% to 15%.

  • Strategies to mitigate Pt dissolution in low Pt loading proton exchange membrane fuel cell: II. A gradient Pt loading design
    Electrochimica Acta, 2017
    Co-Authors: Haoran Yu, Andrea Baricci, Andrea Casalegno, L. Guétaz, Leonard Bonville, Radenka Maric
    Abstract:

    In the second companion paper on low Pt-loaded gradient cathode, the degradation of Type II cathode with higher Pt loading (60 wt%) near the cathode/membrane interface was studied and compared to a control cathode with uniform Pt loading (40 wt%). All catalyst coated membranes were deposited through reactive spray deposition technology with average Pt particle size of 2 nm and Pt loadings of 0.05 mg cm−2and 0.1 mg cm−2on anode and cathode, respectively. The Type II cathode showed improved fuel cell performance at beginning-of-test (BOT) due to higher Pt utilization benefited from high Pt loading close to the membrane. Although the loss of electrochemical surface area for the Type II cathode was ∼80%, similar to that of the control cathode, the end-of-test performance (EOT) was improved by 50–100 mV, which can be attributed to the reduction of Pt loss in the Pt Depletion Zone (from 80% to 60%) as well as from 30% to 18% for the entire cathode. A comparison between Type I and Type II cathode was made in terms of Pt retention and particle size distribution. Type II cathode turned out to be more effective than Type I cathode as a result of being able to maintain a higher percentage of smaller particles (

Andrea Casalegno - One of the best experts on this subject based on the ideXlab platform.

  • Strategies to mitigate Pt dissolution in low Pt loading proton exchange membrane fuel cell: I. A gradient Pt particle size design
    Electrochimica Acta, 2017
    Co-Authors: Haoran Yu, Andrea Baricci, Andrea Bisello, Andrea Casalegno, L. Guétaz, Leonard Bonville, Radenka Maric
    Abstract:

    The catalyst durability at low Pt loading remains a barrier for industrial commercialization of the proton exchange membrane fuel cell. Degradation of low loaded Pt catalyst not only reduced the electrochemical surface area but also revealed a Pt Depletion Zone adjacent to the cathode/membrane interface where about 80% of the Pt was lost due to dissolution and migration into the membrane. We hypothesized that the Pt degradation can be mitigated using a gradient cathode design without sacrificing the initial fuel cell performance. With a focus on the mitigation, the first of two companion papers focuses on the Type I cathode with larger Pt particles (5 nm average size) near the cathode/membrane interface. In the second of these two papers, the Type II cathode with higher Pt loading (60 wt.% Pt on carbon) near the cathode membrane interface will be investigated. The catalyst coated membranes with gradient cathode were fabricated by reactive spray deposition technology with low Pt loading of 0.05 mg cm−2on the anode and 0.1 mg cm−2on the cathode. The DOE defined accelerated stress test was performed by imposing a triangular wave potential cycling from 0.6 V to 1.0 V for 30,000 cycles at 50 mV s−1scan rate. Results of accelerated stress test showed that the loss of electrochemical surface area and PEMFC performance were reduced for the Type I cathode compared to the control cathodes that consisted of 2 nm averaged Pt particle size only. Microscopy analysis suggested two possible mechanisms for this durability improvement: 1) the reduction of the amount of Pt lost due to Pt dissolution, and 2) the preservation of Pt particles at the cathode/membrane interface. Comparison with the control cathode showed that the loss of Pt near the cathode/membrane interfaced were reduced from 80% to 40% and the overall Pt loss of the cathode were reduced from 30% to 15%.

  • Strategies to mitigate Pt dissolution in low Pt loading proton exchange membrane fuel cell: II. A gradient Pt loading design
    Electrochimica Acta, 2017
    Co-Authors: Haoran Yu, Andrea Baricci, Andrea Casalegno, L. Guétaz, Leonard Bonville, Radenka Maric
    Abstract:

    In the second companion paper on low Pt-loaded gradient cathode, the degradation of Type II cathode with higher Pt loading (60 wt%) near the cathode/membrane interface was studied and compared to a control cathode with uniform Pt loading (40 wt%). All catalyst coated membranes were deposited through reactive spray deposition technology with average Pt particle size of 2 nm and Pt loadings of 0.05 mg cm−2and 0.1 mg cm−2on anode and cathode, respectively. The Type II cathode showed improved fuel cell performance at beginning-of-test (BOT) due to higher Pt utilization benefited from high Pt loading close to the membrane. Although the loss of electrochemical surface area for the Type II cathode was ∼80%, similar to that of the control cathode, the end-of-test performance (EOT) was improved by 50–100 mV, which can be attributed to the reduction of Pt loss in the Pt Depletion Zone (from 80% to 60%) as well as from 30% to 18% for the entire cathode. A comparison between Type I and Type II cathode was made in terms of Pt retention and particle size distribution. Type II cathode turned out to be more effective than Type I cathode as a result of being able to maintain a higher percentage of smaller particles (