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Full-Text Articles in Engineering
Understanding The Effect Of Balance Of Plant Contaminants On Pemfcs Performance: Models, Mechanisms, Functional Group, Hyun-Seok Cho
Understanding The Effect Of Balance Of Plant Contaminants On Pemfcs Performance: Models, Mechanisms, Functional Group, Hyun-Seok Cho
Theses and Dissertations
This dissertation considers contamination of a proton exchange membrane fuel cell (PEMC) that may result from chemicals that leach from balance of plant (BOP) materials. Both model predictions and experimental data are presented. The model is used to predict the cathode contamination impact on the Pt/C electrode and the membrane assuming no transport of contaminant from cathode to anode. The model prediction accounts for the contamination mechanisms such as adsorption, ion-exchange, absorption and three sources of voltage (i.e., performance) loss. The simple 2-D time-dependent model is developed by considering well known chemical engineering concepts of Langmuir adsorption, partition coefficients, plug …
Mesoporous Tin Oxide As An Oxidation-Resistant Catalyst Support For Proton Exchange Membrane Fuel Cells, Peng Zhang, Sheng-Yang Huang, Branko N. Popov
Mesoporous Tin Oxide As An Oxidation-Resistant Catalyst Support For Proton Exchange Membrane Fuel Cells, Peng Zhang, Sheng-Yang Huang, Branko N. Popov
Faculty Publications
Mesoporous catalyst support based on tin oxide (SnO2) is synthesized with high surface area of 205 m2 g−1 and with narrow pore size distribution. Modified polyol method is used to deposit platinum on SnO2. The physical properties of the support and the SnO2-supported Pt catalyst (Pt/SnO2) are characterized by using the Brunauer, Emmett, and Teller method, X-ray diffraction, and transmission electron microscopy. The electrochemical stability and durability of the Pt/SnO2 catalyst are investigated by the accelerated stress tests proposed by the U.S. Department of Energy. Pt/SnO2 catalyst exhibits …
Hydrogen Peroxide Formation Rates In A Pemfc Anode And Cathode: Effect Of Humidity And Temperature, Vijay A. Sethuraman, John W. Weidner, Andrew T. Haug, Sathya Motupally, Lesia V. Protsailo
Hydrogen Peroxide Formation Rates In A Pemfc Anode And Cathode: Effect Of Humidity And Temperature, Vijay A. Sethuraman, John W. Weidner, Andrew T. Haug, Sathya Motupally, Lesia V. Protsailo
Faculty Publications
Hydrogen peroxide (H2O2) formation rates in a proton exchange membrane fuel cell (PEMFC) anode and cathode were estimated as a function of humidity and temperature by studying the oxygen reduction reaction (ORR) on a rotating ring disk electrode. Fuel cell conditions were replicated by depositing a film of Pt/Vulcan XC-72 catalyst onto the disk and by varying the temperature, dissolved O2 concentration, and the acidity levels in hydrochloric acid (HClO4). The HClO4 acidity was correlated to ionomer water activity and hence fuel cell humidity. The H2O2 formation rates showed …
Durability Of Perfluorosulfonic Acid And Hydrocarbon Membranes: Effect Of Humidity And Temperature, Vijay A. Sethuraman, John W. Weidner, Andrew T. Haug, Lesia V. Protsailo
Durability Of Perfluorosulfonic Acid And Hydrocarbon Membranes: Effect Of Humidity And Temperature, Vijay A. Sethuraman, John W. Weidner, Andrew T. Haug, Lesia V. Protsailo
Faculty Publications
The effect of humidity on the chemical stability of two types of membranes [i.e., perfluorosulfonic acid type (PFSA, Nafion 112) and biphenyl sulfone hydrocarbon type, (BPSH-35)] was studied by subjecting the membrane electrode assemblies (MEAs) to open-circuit voltage (OCV) decay and potential cycling tests at elevated temperatures and low inlet-gas relative humidities. The BPSH-35 membranes showed poor chemical stability in ex situ Fenton tests compared to that of Nafion membranes. However, under fuel cell conditions, BPSH-35 MEAs outperformed Nafion 112 MEAs in both the OCV decay and potential cycling tests. For both membranes, (i) at a given temperature, …
Effect Of Diphenyl Siloxane On The Catalytic Activity Of Pt On Carbon, Vijay A. Sethuraman, John W. Weidner, Lesia V V. Protsailo
Effect Of Diphenyl Siloxane On The Catalytic Activity Of Pt On Carbon, Vijay A. Sethuraman, John W. Weidner, Lesia V V. Protsailo
Faculty Publications
The effect of silicone on the catalytic activity of Pt for oxygen reduction and hydrogen adsorption was studied using diphenyl siloxane as a source compound at a rotating disk electrode (RDE). Diphenyl siloxane did not affect the catalytic activity of Pt when it was injected into the electrolyte. However, it blocked the oxygen reduction reaction when it was premixed with the catalyst. Proton transport was not blocked in either case. We postulate that diphenyl siloxane induces hydrophobicity and causes local water starvation, thereby blocking oxygen transport. Hence, the slow leaching of silicone seals in a fuel cell could cause silicon …
Novel Pemfc Cathodes Prepared By Pulse Deposition, Subasri M. Ayyadurai, Yoon-Seok Choi, Prabhu Ganesan, Swaminatha P. Kumaraguru, Branko N. Popov
Novel Pemfc Cathodes Prepared By Pulse Deposition, Subasri M. Ayyadurai, Yoon-Seok Choi, Prabhu Ganesan, Swaminatha P. Kumaraguru, Branko N. Popov
Faculty Publications
A pulse electrodeposition method of preparing thin platinum catalyst layers for polymer electrolyte membrane fuel cell (PEMFC) cathodes has been developed through surface activation of the gas diffusion layer (GDL) by a wetting agent. The performance of the catalyst layer was optimized by wetting agent type, immersion time in the wetting agent, and pulse deposition parameters such as total charge density, peak current density, and duty cycle ratio. The Toff time played a more important role than the Ton time in determining the electrode characteristics such as high concentration of Pt, smaller particle size, and loading. Pt cathodes …
Development Of Method For Synthesis Of Pt–Co Cathode Catalysts For Pem Fuel Cells, Xuguang Li, Héctor R. Colón-Mercado, Gang Wu, Jong-Won Lee, Branko N. Popov
Development Of Method For Synthesis Of Pt–Co Cathode Catalysts For Pem Fuel Cells, Xuguang Li, Héctor R. Colón-Mercado, Gang Wu, Jong-Won Lee, Branko N. Popov
Faculty Publications
A procedure was developed to synthesize a platinum–cobalt (Pt–Co) alloy electrocatalyst for oxygen reduction using Co/C composite as a support. The Pt–Co/C catalysts were synthesized through: (i) chemical oxidation of carbon black, (ii) Co deposition on the oxidized carbon using a chelation method, (iii) chemical treatment in an acidic medium to remove excess of Co on the carbon surface, (iv) Pt deposition onto the Co/C support, and (v) postheat treatment to form the Pt–Co alloy catalyst. The synthesized Pt–Co/C catalyst showed improved activity and long-term stability in polymer electrolyte membrane …
Parameter Estimates For A Pemfc Cathode, Qingzhi Guo, Vijay A. Sethuraman, Ralph E. White
Parameter Estimates For A Pemfc Cathode, Qingzhi Guo, Vijay A. Sethuraman, Ralph E. White
Faculty Publications
Five parameters of a model of a polymer electrolyte membrane fuel cell (PEMFC) cathode (the volume fraction of gas pores in the gas diffusion layer, the volume fraction of gas pores in the catalyst layer, the exchange current density of the oxygen reduction reaction, the effective ionic conductivity of the electrolyte, and the ratio of the effective diffusion coefficient of oxygen in a flooded spherical agglomerate particle to the square of that particle radius) were determined by least-squares fitting of experimental polarization curves. The values of parameters obtained in this work indicate that ionic conduction and gas-phase transport are two …
A Steady-State Impedance Model For A Pemfc Cathode, Qingzhi Guo, Ralph E. White
A Steady-State Impedance Model For A Pemfc Cathode, Qingzhi Guo, Ralph E. White
Faculty Publications
A model for the simulation of the steady-state impedance response of a polymer electrolyte membrane fuel cell (PEMFC) cathode is presented. The catalyst layer of the electrode is assumed to consist of many flooded spherical agglomerate particles surrounded by a small volume fraction of gas pores. Stefan-Maxwell equations are used to describe the multicomponent gas-phase transport occurring in both the gas diffusion layer and the catalyst layer of the electrode. Liquid-phase diffusion of O2 is assumed to take place in the flooded agglomerate particles. Newman’s porous electrode theory is applied to determine over-potential distributions. © 2004 The Electrochemical Society. All …
Polyetheretherketone Membranes For Elevated Temperature Pemfcs, Balasubramanian Lakshmanan, Wayne Huang, David Olmeijer, John W. Weidner
Polyetheretherketone Membranes For Elevated Temperature Pemfcs, Balasubramanian Lakshmanan, Wayne Huang, David Olmeijer, John W. Weidner
Faculty Publications
Membrane electrode assemblies ~MEAs! made from polyetheretherketone ~PEEK! showed excellent fuel cell performance and thermal stability in the presence of substantial CO at elevated temperatures ~i.e., 120°C! in proton exchange membrane fuel cells ~PEMFCs!. For example, the current from a MEA made from PEEK membrane at 0.6 V and 120°C was 0.50 A/cm2 when run on pure hydrogen and 0.45 A/cm2 when run on reformate ~50% H2 , 1300 ppm CO, and balance N2). The current density from a MEA made from Nafion at 0.6 V and 120°C was 0.61 A/cm2 when run on pure hydrogen. The main difference between …
Study Of Ionic Conductivity Profiles Of The Air Cathode Of A Pemfc By Ac Impedance Spectroscopy, Qingzhi Guo, Maria Cayetana, Yu-Min Tsou, Emory S. De Castro, Ralph E. White
Study Of Ionic Conductivity Profiles Of The Air Cathode Of A Pemfc By Ac Impedance Spectroscopy, Qingzhi Guo, Maria Cayetana, Yu-Min Tsou, Emory S. De Castro, Ralph E. White
Faculty Publications
A characterization of the ionic conduction of the active layer of a polymer electrolyte membrane fuel cell (PEMFC) cathode by ac impedance measurement at open-circuit potential conditions was conducted. Porous electrode theory was used to derive a compact equation, ∂2Φ̑2/∂y2+∂lnf(y)/∂y×∂Φ̑2/∂y−R/f(y)(1+jΩ)Φ̑2=0, to solve for the impedance response of a cathode at open-circuit potential conditions. This equation includes a parameter R, the ratio of an ionic resistance (evaluated at the active layer/membrane interface), to the total charge-transfer resistance of the active layer. The influence of an assumed ionic conductivity distribution profile f(y) on the error in the estimation of total double-layer …
Using Sputter Deposition To Increase Co Tolerance In A Proton-Exchange Membrane Fuel Cell, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang, Steven Shi, Narender Rana, Stephan Grunow, Timothy C. Stoner, Alain E. Kaloyeros
Using Sputter Deposition To Increase Co Tolerance In A Proton-Exchange Membrane Fuel Cell, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang, Steven Shi, Narender Rana, Stephan Grunow, Timothy C. Stoner, Alain E. Kaloyeros
Faculty Publications
Placing a layer of Ru atop a Pt anode increases the carbon monoxide tolerance of proton-exchange membrane fuel cells when oxygen is added to the fuel stream. Sputter-deposited Ru filter anodes composed of a single Ru layer and three Ru layers separated by Nafion-carbon ink, respectively, were compared to Pt, Pt:Ru alloy, and an ink-based Ru filter anodes. The amount of Pt in each anode was 0.15 mg/cm2 and the amount of Ru in each Ru-containing anode was 0.080 mg/cm2. For an anode feed consisting of hydrogen, 200 ppm CO, and 2% O2 (in the form …
Electrochemical Filtering Of Co From Fuel-Cell Reformate, Balasubramanian Lakshmanan, Wayne Huang, John W. Weidner
Electrochemical Filtering Of Co From Fuel-Cell Reformate, Balasubramanian Lakshmanan, Wayne Huang, John W. Weidner
Faculty Publications
A proton exchange membrane fuel cell was used as a flow reactor for continuous preferential oxidation of CO over H2 from 1.0% CO in H2 under pulse-potential control. By varying the pulse profile ~e.g., on-time, off-time, pulse potential! the CO and H2 oxidation currents were varied independently. The improvement in faradaic selectivity between CO and H2 oxidation results from the promotion of CO adsorption during the off ~i.e., open-circuit! portion of the pulse. Therefore, during the on portion CO oxidation was preferred while the surface was covered with CO.
Increasing Proton Exchange Membrane Fuel Cell Catalyst Effectiveness Through Sputter Deposition, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang, Steven Shi, Timothy Stoner, Narender Rana
Increasing Proton Exchange Membrane Fuel Cell Catalyst Effectiveness Through Sputter Deposition, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang, Steven Shi, Timothy Stoner, Narender Rana
Faculty Publications
Sputter deposition has been investigated as a tool for manufacturing proton-exchange membrane fuel cell (PEMFC) electrodes with improved performance and catalyst utilization vs. ink-based electrodes. Sputter-depositing a single layer of Pt on the gas diffusion layer provided better performance (0.28 A/cm2 at 0.6 V) than sputtering the Pt directly onto a Nafion membrane (0.065 A/cm2 at 0.6 V) and equaled the performance of the baseline for an equivalent Pt loading. Sputter-depositing alternating layers of Pt and Nafion-carbon ink (NCI) onto the membrane did not increase the performance over the baseline as measured in amperes per centimeter squared due …
Development Of A Novel Co Tolerant Proton Exchange Membrane Fuel Cell Anode, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang
Development Of A Novel Co Tolerant Proton Exchange Membrane Fuel Cell Anode, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang
Faculty Publications
Typically Pt is alloyed with metals such as Ru, Sn, or Mo to provide a more CO-tolerant, high-performance proton exchange membrane fuel cell (PEMFC) anode. In this work, a layer of carbon-supported Ru is placed between the Pt catalyst and the anode flow field to form a filter. When oxygen is added to the fuel stream, it was predicted that the slow H2 kinetics of Ru in this filter would become an advantage compared to Pt and Pt:Ru alloy anodes, allowing a greater percentage of O2 to oxidize adsorbed CO to CO2. With an anode feed …
Theoretical Analysis Of The Discharge Performance Of A Niooh/H2 Cell, Z. Mao, P. De Vidts, Ralph E. White, John Newman
Theoretical Analysis Of The Discharge Performance Of A Niooh/H2 Cell, Z. Mao, P. De Vidts, Ralph E. White, John Newman
Faculty Publications
A mathematical model is presented for the discharge of a NiOOH/H2 cell. This model includes diffusion and migration in the electrolyte phase as well as proton diffusion and ohmic drop across the solid active material in the porous nickelelectrode. A theoretical analysis of the cell performance is presented for different design parameters using this model. It is predicted that proton diffusion in the solid active material is the main factor in limiting the cell voltage and the utilizationof the active material. It is also predicted that use of a thick nickel electrode is an effective method for increasing electrode …
A Water And Heat Management Model For Proton-Exchange-Membrane Fuel Cells, Trung V. Nguyen, Ralph E. White
A Water And Heat Management Model For Proton-Exchange-Membrane Fuel Cells, Trung V. Nguyen, Ralph E. White
Faculty Publications
Proper water and heat management are essential for obtaining high-power-density performance at high energy efficiency for proton-exchange-membrane fuel cells. A water and heat management model was developed and used to investigate the effectiveness of various humidification designs. The model accounts for water transport across the membrane by electro-osmosis and diffusion, heat transfer from the solid phase to the gas phase and latent heat associated with water evaporation and condensation in the flow channels. Results from the model showed that at high current densities (> 1 A/cm2) ohmic loss in the membrane accounts for a large fraction of the …
Oxygen Reduction In A Proton Exchange Membrane Test Cell, S. J. Ridge, Ralph E. White, Y. Tsou, R. N. Beaver, G. A. Eisman
Oxygen Reduction In A Proton Exchange Membrane Test Cell, S. J. Ridge, Ralph E. White, Y. Tsou, R. N. Beaver, G. A. Eisman
Faculty Publications
Oxygen reduction in a gas-fed porous electrode attached to a proton exchange membrane is discussed. Experimental data and a mathematical model are presented for the test cell used. Various membrane and electrode assemblies were tested at different levels of platinum loading and Teflon® content. The model accounts for the diffusion and reaction of oxygen and the diffusion and reaction of hydrogen ions. Sulfuric acid was placed above the membrane in the test cell reservoir to provide a source of protons for the reduction of oxygen at the cathode. Based upon model predictions, it is shown that the transport of the …