Proton Exchange Membrane Research Papers (original) (raw)

Deep Inelastic Neutron Scattering provides a means of directly and accurately measuring the momentum distribution of protons in water, which is determined primarily by the protons ground state wavefunction. We find that in water confined on scales of 20A, this wave function responds to the details of the confinement, corresponds to a strongly anharmonic local potential, shows evidence in some cases of coherent delocalization in double wells, and involves changes in zero point kinetic energy of the protons from -40 to +120 meV difference from that of bulk water at room temperature. This behavior appears to be a generic feature of nanoscale confinement. It is exhibited here in 16A inner diameter carbon nanotubes, two different hydrated proton exchange membranes(PEMs), Nafion 1120 and Dow 858, and has been seen earlier in xerogel and 14A diameter carbon nanotubes. The proton conductivity in the PEM samples correlates with the degree of coherent delocalization of the proton.

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- Proton Exchange Membrane, Carbon Nanotube, Inelastic Neutron Scattering, Room Temperature

An investigation of the electrochemical activity of human white blood cells (WBC) for biofuel cell (BFC) applications is described. WBCs isolated from whole human blood were suspended in PBS and introduced into the anode compartment of a proton exchange membrane (PEM) fuel cell. The cathode compartment contained a 50 mM potassium ferricyanide solution. Average current densities between 0.9 and 1.6 μA cm-2 and open circuit potentials (Voc) between 83 and 102 mV were obtained, which were both higher than control values. Cyclic voltammetry was used to investigate the electrochemical activity of the activated WBCs in an attempt to elucidate the mechanism of electron transfer between the cells and electrode. Voltammograms were obtained for the WBCs, including peripheral blood mononuclear cells (PBMCs - a lymphocyte-monocyte mixture isolated on a Ficoll gradient), a B lymphoblastoid cell line (BLCL), and two leukemia cell lines, namely K562 and Jurkat. An oxidation peak at about 363 mV vs...

- by Yingze Zhang
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- Biology, Proton Exchange Membrane, Cyclic Voltammetry, Medicine

A novel sulfonated diamine monomer, 1,4-bis(4-aminophenoxy)-naphthyl-2,7-disulfonic acid (BAPNDS), was synthesized. A series of sulfonated polyimide copolymers were prepared from BAPNDS, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and nonsulfonated diamine 4,4′-diaminodiphenyl ether (ODA). Flexible, transparent, and mechanically strong membranes were obtained. The membranes displayed slightly anisotropic membrane swelling. The dimensional change in thickness direction was larger than that in planar. The novel SPI membranes showed higher conductivity, which was comparable or even higher than Nafion 117. Membranes exhibited methanol permeability from 0.24 × 10−6 to 0.80 × 10−6 cm2/s at room temperature, which was much lower than that of Nafion (2 × 10−6 cm2/s). The copolymers were thermally stable up to 340 °C. These preliminary results have proved its potential availability as proton-exchange membrane for PEMFCs or DMFCs.

- by Yuhan Li
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- Engineering, Materials Engineering, Chemical Engineering, Proton Exchange Membrane

A 3D numerical study was carried out to analyze flow, heat and mass transfer first in a single half-cell cathode channel of proton exchange membrane (PEM) fuel cell. From practical point of view, it is necessary to put the appropriate number of cells in a stack. Hence, the above study on a single half-cell is extended to a stack of channels. Due to stacking, the assumption of uniform flow distribution would no longer hold true. Therefore, the channel flow-maldistribution is considered. The water formed at the active surface due to the electrochemical reaction diffuses through the porous layer and eventually enters the gas flow duct. The higher gas velocities in the duct result in faster water vapour removal which leads to a lower value of water vapour into the duct and hence a lower Nusselt number.

- by Siddharth Patel
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- Proton Exchange Membrane, Fuel Cell, Heat and Mass Transfer, Numerical Simulation

Water removal from the gas diffusion layer (GDL) is crucial for the efficient operation of proton exchange membrane (PEM) fuel cell. Static pressure gradient caused by the fast reactant flow in the flow channel is one of the main mechanisms of water removal from GDL. Reactant can leak or cross directly to the neighboring channel via the porous GDL in the cells with serpentine flow channel and many of its modifications. Such cross flow plays an important role for the removal of liquid water accumulated in the GDL especially under land area. To investigate the characteristics of liquid water behavior in the GDL under pressure gradient, the fibrous porous structure of the carbon paper is modeled by three dimensional impermeable cylinders randomly distributed in the in-plane directions and unsteady two-phase simulations are conducted. It is shown that the permeability from the numerical model matches well the experimental measurements of the common GDLs in the literature. The contact angle and pressure gradient are the key parameters that determine the initiation and the process of liquid water transport in the GDL which is initially wet with stagnant liquid water. It has been observed that the larger contact angle results in faster water removal from the GDL. Numerical simulations are performed for a wide range of pressure gradient with different contact angles to determine the minimum pressure gradient that initiates the liquid water transport in the GDL. It is found that the amount of pressure gradient caused by the cross flow is sufficient and effective to get rid of the liquid water accumulated in the GDL. The simulation results are also compared with experimental data in literature showing a good agreement. The characteristics of liquid water discharging from the gas diffusion layer are also described.

- by Xianguo Li
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- Engineering, Economics, Proton Exchange Membrane, Numerical Simulation

The objective of this study is to determine the effects of various factors on the performance of proton exchange membrane (PEM) fuel cell. These factors are membrane thickness, hot-pressing conditions of the gas diffusion layer (GDL) either onto the membrane or membrane electrode assembly (MEA) and Teflon:carbon ratio in the GDL on PEM fuel cell performance. Homemade five-layer and commercial three-layer MEAs were used in the experiments. Nafion®® 112 and 115 which have nominal thicknesses of 50 and 125μm, respectively, were used as membranes. It was observed that fuel cell performance is inversely proportional to membrane thickness. In the case of five-layer MEAs, optimum hot-pressing conditions of catalyst-coated GDLs onto the membrane were found as 172Ncm-2. However, the maximum performance for three-layer MEAs was obtained with no press conditions. Also, by increasing Teflon:carbon ratio in the GDLs, PEM fuel cell performance increases up to a certain value, but further increase of this ratio worsen the performance.

- by Ayse Bayrakceken and +1
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- Engineering, Proton Exchange Membrane, Performance, Fuel Cell

This paper reviews over 120 papers regarding the effect of heat treatment on the catalytic activity and stability of proton exchange membrane (PEM) fuel cell catalysts. These catalysts include primarily unsupported and carbon-supported platinum (Pt), Pt alloys, non-Pt alloys, and transition metal macrocycles. The heat treatment can induce changes in catalyst properties such as particle size, morphology, dispersion of the metal on the support, alloying degree, active site formation, catalytic activity, and catalytic stability. The optimum heat-treatment temperature and time period are strongly dependent on the individual catalyst. With respect to Pt-based catalysts, heat treatment can induce particle-size growth, better alloying degree, and changes in the catalyst surface morphology from amorphous to more ordered states, all of which have a remarkable effect on oxygen reduction reaction (ORR) activity and stability. However, heat treatment of the catalyst carbon supports can also significantly affect the ORR catalytic activity of the supported catalyst. Regarding non-noble catalysts, in particular transition metal macrocycles, heat treatment is also important in ORR activity and stability improvement. In fact, heat treatment is a necessary step for introducing more active catalytic sites. For metal chalcogenide catalysts, it seems that heat treatment may not be necessary for catalytic activity and stability improvement. More research is necessary to improve our fundamental understanding and to develop a new strategy that includes innovative heat-treatment processes for enhancing fuel cell catalyst activity and stability.

- by Aldaléa Lopes Brandes Marques
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- Engineering, Proton Exchange Membrane, Heat Treatment, Fuel Cell

An optimization study of components and assembling characteristics for a proton exchange membrane (PEM) short stack electrolyzer (3 cells of 100 cm 2 geometrical area) was carried out. The electrochemical properties were investigated by polarization, impedance spectroscopy and chrono-potentiometric measurements. A decrease of the ohmic contact resistance between the bipolar plates and the electrode backing layer was obtained by using an appropriate thickness for the gas diffusion layers/current collectors as well as by an optimization of stack compression. The amount of H 2 produced was w90 l h À1 at 60 A (600 mA cm À2) and 75 C under 300 W of applied electrical power. No significant leakage or gas recombination was observed. The stack electrical efficiency was 75% and 88%, at 60 A and 75 C, with respect to the low and high heating value of hydrogen, respectively.

- by Ruben Ornelas
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- Engineering, Proton Exchange Membrane, Impedance Spectroscopy, Hydrogen Energy

A dynamic model of a discrete reversible fuel cell (RFC) system has been developed in a Matlab Simulink ® environment. The model incorporates first principles dynamic component models of a proton exchange membrane (PEM) fuel cell, a PEM electrolyzer, a metal hydride hydrogen storage tank, and a cooling system radiator, as well as empirical models of balance of plant components. Dynamic simulations show unique charging and discharging control issues and highlight factors contributing to overall system efficiency.

- by Franklin Holcomb
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- Engineering, Proton Exchange Membrane, Hydrogen Storage, Fuel Cell

A simple method is described to synthesize carbon nanotubes (CNTs) by the thermal decomposition of toluene at 750°C over a thin catalyst film deposited on Al powder. This method allows the bulk metal surface to act as both the catalyst and support for CNT growth. The catalyst film on Al was prepared from an ethanol solution of iron nitrate. Under the growth conditions, iron nitrate formed an amorphous iron oxide layer that transform into crystalline Fe 2 O 3 , which was further reduced to Fe 3 O 4 and Fe 3 C. It is believed that the growth of CNTs took place on iron carbide nanoparticles that were formed from FeO. The characterization of CNTs was mainly carried out by powder X-ray diffraction and scanning electron microscopy, X-ray fluorescence and thermogravimatric analysis. The CNTs were found to be highly dispersed in Al powder. This composite powder could be further used for the fabrication of Al matrix composites using powder metallurgy process in which the powder were first cold pressed at 500-550 MPa followed by sintering at 620°C for 2 h under a vacuum of 10 -2 torr. The mechanical properties of the sintered composites were measured using a microhardness tester and a Universal testing Instron machine.

(FS) was prepared and copolymerized with chloromethylstyrene (CMS). Conventional radical copolymerization of both these aromatic monomers led to poly(CMS-co-FS) random copolymers for which CMS was shown to be more reactive than the fluorinated comonomer. Their controlled radical copolymerization based on degenerative transfer, namely iodine transfer polymerization (ITP), led to various poly(CMS)-b-poly(FS) block copolymers. Molecular weights of poly(CMS-co-FS) copolymers reached 33,000 g mol À1 while those of poly(CMS)-bpoly(FS) block copolymers were 22,000 g mol À1. Their composition ranged from 18 to 61 mol.% in FS. These copolymers were modified via a cationization step, aiming at replacing the

Biofouling Pre-treatment of Nafion Ò a b s t r a c t Nafion Ò 117, as the most popular proton exchange membrane, has been studied with regards to the effect of pre-treatment and biofouling for bioelectricity production and wastewater treatment, in dual chamber microbial fuel cells. The obtained results showed that maximum generated power was obtained using pre-treated Nafion Ò 117, at approximately 100 mW/m 2 . However, maximum generated power for untreated Nafion Ò 117 and biofouled Nafion Ò 117 were 52.8 mW/m 2 and 20.9 mW/m 2 , respectively. Furthermore, the columbic efficiency of pre-treated Nafion Ò 117 was 2.32 and 4.15 times higher than untreated and biofouled Nafion Ò 117, respectively. Obtained results demonstrated that the pre-treatment of the proton exchange membrane is necessary to reach higher powers, and biofouling is a major obstacle for proton exchange membranes in dual chamber MFCs.

- by Mostafa Rahimnejad
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- Engineering, Proton Exchange Membrane, Hydrogen Energy, Biofouling

Hydrogen production by a proton exchange membrane (PEM) electrolyzer provides a promising way to store and better utilize the renewable energy resources. Presently, theoretical studies on PEM electrolyzer are still limited, impeding its technological development. Detailed thermodynamic analysis is valuable to identify the key losses and to optimise the performance of PEM electrolyzer plant for hydrogen production. In this study, energy and exergy analysis has been conducted to investigate the thermodynamic-electrochemical characteristics of hydrogen production by a PEM electrolyzer plant. One important feature of this model is that detailed electrochemical characteristics of the PEM electrolyzer are fully incorporated into the thermodynamic analysis. Heat production in the PEM cell due to irreversible losses has been investigated and compared with the thermal energy demand of PEM cell. It is found that a PEM electrolyzer normally operates in an exothermic mode as the heat production due to overpotentials exceeds the thermal energy demand. As the electrical energy input dominates the overall energy input, the exergy efficiency is found about the same as the energy efficiency. Parametric analyses have been performed to investigate the effect of important design and operating parameters on the plant energy conversion efficiency. This study has quantified how much the energy efficiency can decreases by increasing the operating temperature, lowering the current density, reducing the electrolyte thickness, and increasing the electrode catalytic activity. The analysis presented in this paper also offers better understanding of the characteristics of PEM electrolyzer plant for hydrogen production. With additional energy analysis of electricity generated from solar cells or wind turbines, the model presented in this paper is ready for complete energy/exergy analysis of advanced renewable electrolytic hydrogen production plants.

- by Mateusz Bryk
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- Thermodynamics, Solar Cell, Proton Exchange Membrane, Energy Conversion
- by Dennis Curtin and +1
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- Inorganic Chemistry, Organic Chemistry, Proton Exchange Membrane, Fluorine Chemistry

A comprehensive, steady-state, computational model of a proton exchange membrane fuel cell (PEMFC) derived from first principles is presented. The model is two-dimensional and includes the transport of liquid water within the porous electrodes as well as the transport of gaseous species, protons, energy, and water dissolved in the ion conducting polymer. Electrochemical kinetics are modeled with standard rate equations adapted to an agglomerate catalyst layer structure. Some of the physical properties used in constructing the model are determined experimentally for an in-house membrane electrode assembly (MEA) and are presented herein. Experimental results obtained for the MEA are used to validate the computational model. Modeling results are presented that illustrate the importance of the transport of water within the porous sections of the cell and in the polymer regions of the MEA. (M.W. Ellis).

- by M. von Spakovsky
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- Engineering, Kinetics, Proton Exchange Membrane, Computer Model

Performance of microbial fuel cells (MFCs), fabricated using an earthen pot (MFC-1) and a proton exchange membrane (MFC-2), was evaluated while treating rice mill wastewater at feed pH of 8.0, 7.0 and 6.0. A third MFC (MFC-3), fabricated using a proton exchange membrane (PEM), was operated as control without pH adjustment of the acidic raw wastewater. Maximum chemical oxygen demand (COD) removal efficiencies of 96.5% and 92.6% were obtained in MFC-1 and MFC-2, respectively, at feed pH of 8.0. MFC-3 showed maximum COD removal of 87%. The lignin removal was 84%, 79%, and 77% and the phenol removal was 81%, 77%, and 76% in MFC-1, MFC-2, and MFC-3, respectively. Maximum sustainable volumetric power was obtained at feed pH of 8.0, and it was 2.3 W/m 3 and 0.53 W/m 3 , with 100 Ω external resistance, in MFC-1 and MFC-2, respectively. The power was lower at lower feed pH. MFC-3 generated lowest volumetric power (0.27 W/m 3 ) as compared to MFC-1 and MFC-2. More effective treatment of rice mill wastewater and higher energy recovery was demonstrated by earthen pot MFC as compared to MFC incorporated with PEM.

- by Tanaji More
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- Bioelectrochemistry, Electrochemistry, Proton Exchange Membrane, Wastewater Treatment

In this communication, safety considerations related to the operation of proton-exchange membrane (PEM) water electrolysers (hydrogen production capacity up to 1 Nm 3 /hour and operating pressure up to 130 bars) are presented. These results were obtained in the course of the GenHyPEM project, a research program on high pressure PEM water electrolysis supported by the European Commission. Experiments were made using a high-pressure electrolysis stack designed for operation in the 0-130 bars pressure range at temperatures up to 90°C. Besides hazards related to the pressure itself, hydrogen concentration in the oxygen gas production and vice-versa (resulting from membrane crossover permeation effects) have been identified as the most significant risks. Results show that the oxygen concentration in hydrogen at 130 bars can be as high as 2.7 vol. %. This is a value still outside the flammability limit for hydrogen-oxygen mixtures (3.9-95.8 vol. %), but safety measures are required to prevent explosion hazards. A simple model based on the diffusion of dissolved gases is proposed to account for gas cross-permeation effects. To reduce contamination levels, different solutions are proposed. First, thicker membranes can be used. Second, modified or composite membranes with lower gas permeabilities can be used. Third, as reported earlier, external catalytic gas recombiners can be used to promote H 2 /O 2 recombination and reduce contamination levels in the gas production. Finally, other considerations related to cell and stack design are also discussed to further reduce operation risks.

- by Fabien AUPRETRE
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- Engineering, High Pressure, Proton Exchange Membrane, Operational Risk

Proton Exchange Membrane (PEM) water electrolysis can be used to produce hydrogen from renewable energy sources and can contribute to reduce CO2 emissions. The purpose of this paper is to report on recent advances made in PEM water electrolysis technology. Results obtained in electrocatalysis (recent progresses made in low-cost electrocatalysis offer new perspectives for decentralized and domestic applications), on low-cost membrane electrode assemblies (MEAs), cell efficiency, operation at high current density, electrochemical performances and gas purity issues during high-pressure operation, safety considerations, stack design and optimization (for electrolyzers which can produce up to 5 Nm3 H2/h) and performance degradations are presented. These results were obtained in the course of the GenHyPEM project, a 39 months long (2005–2008) research program supported by the European Commission. PEM technology has reached a level of maturity and performances which offers new perspectives in view of the so-called hydrogen economy.

- by Rostand Ngameni
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- Engineering, High Pressure, Proton Exchange Membrane, renewable Energy sources

Hydrogen SO 2 -depolarized Proton exchange membrane Electrolyzer Efficiency Silicon carbide Bayonet High-temperature Decomposition Reactor Nuclear Pinch analysis Aspen PlusÔ Flowsheet Model Vacuum distillation a b s t r a c t A conceptual design is presented for a hybrid sulfur process for the production of hydrogen using a high-temperature nuclear heat source to split water. The process combines proton exchange membrane-based SO 2 -depolarized electrolyzer technology being developed at Savannah River National Laboratory with silicon carbide bayonet decomposition reactor technology being developed at Sandia National Laboratories. Both are part of the US DOE Nuclear Hydrogen Initiative. The flowsheet otherwise uses only proven chemical process components. Electrolyzer product is concentrated from 50 wt% sulfuric acid to 75 wt% via recuperative vacuum distillation. Pinch analysis is used to predict the hightemperature heat requirement for sulfuric acid decomposition. An Aspen PlusÔ model of the flowsheet indicates 340.3 kJ high-temperature heat, 75.5 kJ low-temperature heat, 1.31 kJ low-pressure steam, and 120.9 kJ electric power are consumed per mole of H 2 product, giving an LHV efficiency of 35.3% (41.7% HHV efficiency) if electric power is available at a conversion efficiency of 45%.

- by Maximilian Gorensek
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- Engineering, Proton Exchange Membrane, Conceptual Design, Silicon Carbide

Hydrogen may be produced by a number of processes, including electrolysis of water, thermocatalytic reformation of hydrogen-rich organic compounds, and biological processes. Currently, hydrogen is produced, almost exclusively, by electrolysis of water or by steam reformation of methane. Biological production of hydrogen (Biohydrogen) technologies provide a wide range of approaches to generate hydrogen, including direct biophotolysis, indirect biophotolysis, photo-fermentations, and dark-fermentation. The practical application of these technologies to every day energy problems, however, is unclear. In this paper, hydrogen production rates of various biohydrogen systems are compared by ÿrst standardizing the units of hydrogen production and then by calculating the size of biohydrogen systems that would be required to power proton exchange membrane (PEM) fuel cells of various sizes. ?

- by My Love
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- Engineering, Proton Exchange Membrane, Fuel Cell, Hydrogen Energy
- by Siracusano Siracusano
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- Engineering, Chemistry, Proton Exchange Membrane, Hydrogen Energy

Electrolysis Cross-permeation Current efficiency a b s t r a c t A comprehensive overview of the properties of Nafion membranes under electrolysis conditions is presented here to help evaluate and design high-pressure operating proton exchange membrane (PEM) electrolyzers. First, the properties of Nafion membranes are reviewed and summarized based on literature data for PEM electrolysis conditions. Second, the solubility and diffusivity of H 2 and O 2 in liquid water and the PEM are reviewed based on literature data. Finally, the relationship between current density and the impurity of gases is reviewed and discussed. (H. Ito).

- by Akihiro Nakano
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- Engineering, High Pressure, Proton Exchange Membrane, Hydrogen Energy

a b s t r a c t The paper presents dc measurements of proton exchange membranes (PEMs) as an integral part of a membrane electrode assembly (MEA) performed in a novel EasyTest Cell testing device. Depending on their operating temperature PEMs are divided in two groups. The commercial Nafion membranes (Alfa Aesar) as well as the self-prepared interpenetrating network of poly(acrylamidepropylsulfonic acid) and poly(acrylamide) (PAMPS-PAM), and Nafion 117 with grafted PAMPS chains (Nafion graft-PAMPS) are tested in the low temperature range (upto 80 C). The PEMs from the second group (prepared in the frame of EU project AUTOBRANE, FP 6) -phosphoric acid doped polybenzimidazole (PBI/PA) and PBI, containing cross-linked poly(vinylphosphonic acid) (CR-PVPhA) -are investigated for high temperature applications (120-200 C). The EasyTest Cell is a three electrode electrochemical test that offers the possibility to obtain steady state polarization curves at strict self-regulated constant hydrogen and water vapor partial pressures. The initial slope of the polarization curves, corrected by the electronic resistance of the electrodes under study is used as a criterion for the proton conductivity of the investigated PEMs. The results obtained for the commercially available Nafion are in a good agreement with the available literature data. The PAMPS grafting from Nafion 117 results in 1.5 fold higher proton conductivity compared to the non-grafted one. The proton conductivity of the PBI/PA membrane is almost independent on the relative humidity (RH) in the range of 15-40% (0.110-0.117 S cm À1 at 180 C) which makes the water management redundant, this way facilitating the fuel cell management. The proton conductivity of the PBI/CR-PVPhA membrane is in the range of 7 Â 10 À3 S cm À1 (170 C, 20% RH). The EasyTest Cell working principle and single chamber design allows precise control of vital working parameters (temperature and RH) for the proton conductivity of PEM. ª (I. Radev). A v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / h e

- by Evelina Slavcheva and +1
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- Engineering, Proton Exchange Membrane, Fuel Cell, Water Management

Hydrogen Modeling and simulation a b s t r a c t Computational model of a proton exchange membrane (PEM) water electrolyzer is developed to enable investigation of the effect of operating conditions and electrolyzer components on its performance by expending less time and effort than experimental investigations. The work presents a dynamic model of a PEM electrolyzer system based on MATLAB/Simulink software. The model consists mainly of four blocks e anode, cathode, membrane and voltage. Mole balances on the anode and cathode blocks form the basis of the model along with Nernst and ButlereVolmer equations. The model calculates the cell voltage by taking into account the open circuit voltage and various over-potentials. The model developed predicted well the experimental data on PEM water electrolyzer available in the literature. The dynamic behavior of the electrolyzer system is analyzed and the effects of varying electrolyzer temperature and pressure on electrolyzer performance and over-potentials are presented.

- by Suddhasatwa Basu
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- Engineering, Proton Exchange Membrane, Modeling and Simulation, Hydrogen Energy

Efficiency model a b s t r a c t Hydrogen fuel for fuel cell vehicles can be produced by using solar electric energy from photovoltaic (PV) modules for the electrolysis of water without emitting carbon dioxide or requiring fossil fuels. In the past, this renewable means of hydrogen production has suffered from low efficiency (2-6%), which increased the area of the PV array required and therefore, the cost of generating hydrogen. A comprehensive mathematical model was developed that can predict the efficiency of a PV-electrolyzer combination based on operating parameters including voltage, current, temperature, and gas output pressure.

- by Thomas Gibson
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- Engineering, Renewable Energy, Carbon Dioxide, Proton Exchange Membrane

Hydrogen production a b s t r a c t Hydrogen fuel for fuel cell vehicles can be produced by using solar electric energy from photovoltaic (PV) modules for the electrolysis of water without emitting carbon dioxide or requiring fossil fuels. In the past, this renewable means of hydrogen production has suffered from low efficiency (2-6%), which increased the area of the PV array required and therefore, the cost of generating hydrogen. In this research, the efficiency of the PV-electrolysis system was optimized by matching the voltage and maximum power output of the photovoltaics to the operating voltage of proton exchange membrane (PEM) electrolyzers. The optimization process increased the hydrogen generation efficiency to 12% for a solar powered PV-PEM electrolyzer that could supply enough hydrogen to operate a fuel cell vehicle.

- by Thomas Gibson
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- Engineering, Carbon Dioxide, Proton Exchange Membrane, Fuel Cell

In this paper, a graphical model of Proton Exchange Membrane (PEM) electrolyser is presented. The modelling is performed with respect to a generic approach then it is tuned regarding the electrolyser considered for the experimental... more

This investigation examines the economics of producing electricity from proton-exchange membrane (PEM) fuel cell systems under various conditions, including the possibility of using fuel cell vehicles (FCVs) to produce power when they are parked at office buildings and residences. The analysis shows that the economics of both stationary fuel cell and FCV-based power vary significantly with variations in key input variables such as the price of natural gas, electricity prices, fuel cell and reformer system costs, and fuel cell system durability levels. The ''central case'' results show that stationary PEM fuel cell systems can supply electricity for offices and homes in California at a net savings when fuel cell system costs reach about 6000fora5kWhomesystem(6000 for a 5 kW home system (6000fora5kWhomesystem(1200/kW) and 175,000fora250kWcommercialsystem(175,000 for a 250 kW commercial system (175,000fora250kWcommercialsystem(700/kW) and assuming somewhat favorable natural gas costs of 6/GJatresidencesand6/GJ at residences and 6/GJatresidencesand4/GJ at commercial buildings. Grid-connected FCVs in commercial settings can also potentially supply electricity at competitive rates, in some cases producing significant annual benefits. Particularly attractive is the combination of net metering along with timeof-use electricity rates that allow power to be supplied to the utility grid at the avoided cost of central power plant generation. FCVbased power at individual residences does not appear to be as attractive, at least where FCV power can only be used directly or banked with the utility for net metering and not sold in greater quantity, due to the low load levels at these locations that provide a poor match to automotive fuel cell operation, higher natural gas prices than are available at commercial settings, and other factors. r

- by Daniel Kammen and +1
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- Energy Policy, Proton Exchange Membrane, Fuel Cell, Multidisciplinary

This paper presents and studies the mathematical model of proton exchange membrane of fuel cell (PEMFC) using Matlab/SIMULINK software. The paper consists of the calculation of cell voltage, the double layer charging effect, dynamic response and thermodynamic response. This model is used to analyze the fuel cell behavior and the characteristic of output values at different parameters. Two characteristics involved in this paper which are transient and steady-state condition where the results are presented in graphical representation. The parameters for this model in this paper are based on Ballard-Mark-V fuel cell. The maximum power produced by the fuel cell is 3757 watt at load current of 261.4 Amps.

- by Khurram Kamal
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- Thermodynamics, Proton Exchange Membrane, Fuel Cell, Double Layer

Hydrogen production Proton exchange membrane a b s t r a c t Integrated with the renewable energy resources such as wind and solar energy, a Proton Exchange Membrane (PEM) water electrolyzer is one of the important methods for hydrogen production due to its high efficiency, compact structure, releasing no harmful emission and possibility to store the product hydrogen directly to high pressure tanks.

- by mahmut kaplan
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- Engineering, High Pressure, Proton Exchange Membrane, Solar Energy

The H 2 -O 2 proton-exchange membrane (PEM) fuel cell, among numerous other potential applications now slated to provide the motive power for the next generation of highly efficient and largely pollution-free automobiles, is an incomparable membrane reactor, comprising an exquisitely designed membrane-electrode-assembly (MEA), a five-layer composite of two gas-diffusion layers, two supported-catalyst layers, and a PEM. The device allows catalytic reaction and separation of hydrogen and oxygen as well as protons and electrons. This paper describes the structure and performance of the PEM fuel cell considered as a membrane reactor and develops an analytical transport-reaction model that, despite some assumptions, captures the essential features of the device very well. The key assumptions are that transport resistance as well as ohmic drop are negligible in the catalyst layer. While the latter is defensible, the former causes deviations at high current densities. Nonetheless, the model predicts the fuel cell performance well with parameter values reported in the literature.

- by Ravindra Datta
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- Engineering, Proton Exchange Membrane, Fuel Cell, Current Density

Hydrogen production Efficiency a b s t r a c t

- by Vincenzo Baglio
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- Engineering, Proton Exchange Membrane, Hydrogen Energy, Hydrogen Production

Rare earth-based materials can play different roles in fuel cell systems. These compounds can be used as catalysts, co-catalysts and electrolytes additives in different types of fuels cells. In particular, a promising acid direct methanol fuel cell can be obtained using rare earth-based materials as both anode and cathode co-catalysts and proton exchange membrane additive. In this work an overview of the use of rare earth-based materials in low-temperature fuel cells is presented.

- by Joelma Perez
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- Engineering, Proton Exchange Membrane, Fuel Cell, Hydrogen Energy

Proton Exchange Membrane (PEM) fuel cell a b s t r a c t For transportation applications, Proton Exchange Membrane fuel cells (PEMFC) are considered to be the most promising fuel cell technology due to their low operating temperature and pressure resulting in a possible quick start-up. However, to implement them in transportation systems, their reliability should be improved. In the present work, a single fuel cell is considered. It is composed of a membrane, catalyst layers (anode and cathode electrodes) and diffusion layers (anode and cathode electrodes). Those layers are considered as the critical components of the cell. Modelling the process degradations of those components is a great issue. In this work, Fault Tree (FT) is used for this modelling for two main reasons. At first, FT helps to model clearly and intuitively the different causal relations of the degradation mechanisms. Secondly, FT allows quantifying components specific degradations, and their effects on the global degradation of the cell. The cell is considered non repairable. Degradation modelling needs knowledge about mechanisms involving components failures. For 1000 simulations of 100 h operation in cycling conditions, the results of the FT show the most important degradations effects on the global degradation of the cell. This work also proposes degradation probability estimates for some specific events. (R. Kouta).

- by Raed Kouta
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- Engineering, Proton Exchange Membrane, Fuel Cell, Hydrogen Energy

IrO 2 , Ir x Sn (1Àx) O 2 (x ¼ 0.7, 0.5) and Ir x Ru (1Àx) O 2 (x ¼ 0.7, 0.5) electrocatalysts for the oxygen evolution reaction (OER) have been synthesized using the Adams fusion method. The metal oxides were characterized via X-ray diffraction, scanning electron microscopy, inductively coupled plasmaeatomic emission spectrometry and nitrogen adsorptionedesorption measurements to have information about their crystallographic structure, chemical composition and morphology, respectively. A controlled bulk molar fraction of Ru or Sn was introduced in the IrO 2 lattice during the synthesis with no phase separation. The electrocatalytic activity of the synthesized oxides in the OER was studied in liquid electrolyte using porous rotating-disk electrodes, in "half-cell" configuration and in a 5 cm 2 proton-exchange membrane water electrolysis cell. An increase of the electrical performance was observed upon Ru insertion and a severe depreciation upon Sn insertion. (E. Mayousse).

- by Nicolas Guillet and +1
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- Engineering, Proton Exchange Membrane, Scanning Electron Microscopy, Hydrogen Energy

Hydrogen production Water electrolysis IrO 2 catalyst Oxygen evolution reaction a b s t r a c t An optimization study of components and assembling characteristics for a proton exchange membrane (PEM) short stack electrolyzer (3 cells of 100 cm 2 geometrical area) was carried out. The electrochemical properties were investigated by polarization, impedance spectroscopy and chrono-potentiometric measurements. A decrease of the ohmic contact resistance between the bipolar plates and the electrode backing layer was obtained by using an appropriate thickness for the gas diffusion layers/current collectors as well as by an optimization of stack compression. The amount of H 2 produced was w90 l h À1 at 60 A (600 mA cm À2 ) and 75 C under 300 W of applied electrical power. No significant leakage or gas recombination was observed. The stack electrical efficiency was 75% and 88%, at 60 A and 75 C, with respect to the low and high heating value of hydrogen, respectively. (S. Siracusano).

- by V. Baglio and +1
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- Engineering, Proton Exchange Membrane, Impedance Spectroscopy, Hydrogen Energy

Platinum catalyst used in PEM fuel cells experience performance degradation such as reduction in efficiency and life as a result of airborne contaminants. Research on these contaminant effects suggests that the best possible solution to allowing fuel cells to operate in contaminated environments is by filtration of the harmful contaminants from the cathode air. A cathode air filter design methodology was created that considers the properties of the cathode air stream, fuel cell attributes, and filter options to optimize the filter design process. Optimization of the filter requires an understanding of the balance that must be made between the loss in power due to poisoning of the platinum catalyst and a loss in fuel cell efficiency created by an increase in parasitic power required to operate the compressor. The model was successfully applied to a 1.2kWe fuel cell.

- by Donald Cahela
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- Engineering, Proton Exchange Membrane, Performance, Filtration
- by zafar iqbal
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- Proton Exchange Membrane, Carbon Nanotubes, Heat Treatment, Plastics

This review summarizes efforts in developing sulfonated hydrocarbon proton exchange membranes (PEMs) with excellent long-term electrochemical fuel cell performance in medium-temperature and/or low-humidity proton exchange membrane fuel cell (PEMFC) applications. Sulfonated hydrocarbon PEMs are alternatives to commercially available perfluorosulfonic acid ionomers (PFSA, e.g., Nafion ® ) that inevitably lose proton conductivity when exposed to harsh operating conditions. Over the past few decades, a variety of approaches have been suggested to optimize polymer architectures and define postsynthesis treatments in order to further improve the properties of a specific material. Strategies for copolymer syntheses are summarized and future challenges are identified. Research pertaining to the sulfonation process, which is carried out in the initial hydrocarbon PEM fabrication stages, is first introduced. Recent synthetic approaches are then presented, focusing on the polymer design to enhance PEM performance, such as high proton conductivity even with a low ion exchange capacity (IEC) and high dimensional stability. Polymer chemistry methods for the physico-chemical tuning of sulfonated PEMs are also discussed within the framework of maximizing the electrochemical performance of copolymers in membrane-electrode assemblies (MEAs). The discussion will cover crosslinking, surface fluorination, thermal annealing, and organic-inorganic nanocomposite approaches.

- by Michael Guiver
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- Engineering, Proton Exchange Membrane, Fuel Cell, CHEMICAL SCIENCES

AC impedance or electrochemical impedance spectroscopy (EIS) has been demonstrated to be a powerful technique for characterizing and evaluating fuel cells. In this work, as an extension of our previous study on the stack impedance of a 500 W PEM fuel cell, we report the AC impedance studies on individual cells of the same fuel cell stack. The EIS of the stack with an active area of 280 cm 2 was measured at currents from 10 to 210 A in steps of 20 A using the combination of a FuelCon test station, a TDI loadbank and a Solartron 1260 Frequency Response Analyzer. Measurement of the individual cell EIS was carried out with the help of a rotary switch unit made in our lab. Two methods (floating mode and grounded mode) were utilized for measuring the impedance spectroscopy of the individual cells. The results show that both methods are applicable to individual cells. The results also indicate a good agreement between the total Ohmic loss in the stack and the combined Ohmic losses of the individual cells.

- by Mauricio Blanco
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- Engineering, Proton Exchange Membrane, Performance, Fuel Cell

We have reviewed more than 100 references that are related to water management in proton exchange membrane (PEM) fuel cells, with a particular focus on the issue of water flooding, its diagnosis and mitigation. It was found that extensive work has been carried out on the issues of flooding during the last two decades, including prediction through numerical modeling, detection by experimental measurements, and mitigation through the design of cell components and manipulating the operating conditions. Two classes of strategies to mitigate flooding have been developed. The first is based on system design and engineering, which is often accompanied by significant parasitic power loss. The second class is based on membrane electrode assembly (MEA) design and engineering, and involves modifying the material and structural properties of the gas diffusion layer (GDL), cathode catalyst layer (CCL) and membrane to function in the presence of liquid water. In this review, several insightful directions are also suggested for future investigation. Crown

- by Rami Abouatallah and +1
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- Engineering, Proton Exchange Membrane, System Design, Water Management

Proton exchange membrane (PEM) technology is used in water electrolysers, H2/O2 fuel cells and unitized regenerative fuel cells (URFCs). Such electrochemical devices are of particular interest in view of the so-called hydrogen economy. Several prototypes (kW power range) have been developed and tested in the course of the GenHyPEM project (2005–2008), a STREP research program financially supported by the Commission of the European Communities in the frame of the sixth Framework Programme. The purpose of this communication is to report on the current status of each device in terms of performances and technological development. Current limitations and future perspectives are discussed.

- by Rostand Ngameni
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- Engineering, Proton Exchange Membrane, Fuel Cell, Hydrogen Energy

Powders of ruthenium and iridium-based materials were synthesized by the thermal decomposition process. The suitable heat treatment of the polymeric precursors allowed to recover metal oxides free from organic carbon, which can be oxidized to carbon dioxide during H 2 O splitting at elevated potentials. The materials were examined by various physicochemical techniques in order to understand their electrochemical behavior as anodes in a 5 cm 2 single proton exchange membrane water electrolyzer. Although the presence of Ir in the electrocatalyst composition contributes undoubtedly to its stability against ruthenium dissolution and the Faradaic efficiency of the PEM electrolysis cell, its great amount increases the overpotential value. The activity of the home made Ru x Ir 1−x O 2 anodes towards the oxygen evolution reaction occurs at ca. 1.5 V at 25 • C.

- by E. Mayousse and +1
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- Environmental Engineering, Chemical Engineering, Carbon Dioxide, Proton Exchange Membrane

Polymer electrolyte-based unitized reversible fuel cells (URFCs) combine the functionality of a fuel cell and an electrolyzer in a single device. In a URFC, titanium (Ti)-felt is used as a gas diffusion layer (GDL) of the oxygen electrode, whereas typical carbon paper is used as a GDL of the hydrogen electrode. Different samples of Ti-felt with different structural properties (porosity and fiber diameter) and PTFE content were prepared for use as GDLs of the oxygen electrode, and the relation between the properties of the GDL and the fuel cell performance was examined for both fuel cell and electrolysis operation modes. Experimental results showed that the cell with a Ti-felt GDL of 80μm fiber diameter had the highest round-trip efficiency due to excellent fuel cell operation under relatively high-humidity conditions despite degradation in performance in the electrolysis mode.

- by Akihiro Nakano
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- Engineering, Proton Exchange Membrane, Titanium, Fuel Cell

Microbial fuel cells (MFCs) can be used to directly generate electricity from the oxidation of dissolved organic matter, but optimization of MFCs will require that we know more about the factors that can increase power output such as the type of proton exchange system which can affect the system internal resistance. Power output in a MFC containing a proton exchange membrane was compared using a pure culture (Geobacter metallireducens) or a mixed culture (wastewater inoculum). Power output with either inoculum was essentially the same, with 4071 mW/m 2 for G. metallireducens and 3871 mW/m 2 for the wastewater inoculum. We also examined power output in a MFC with a salt bridge instead of a membrane system. Power output by the salt bridge MFC (inoculated with G. metallireducens) was 2.2 mW/m 2 . The low power output was directly attributed to the higher internal resistance of the salt bridge system ð19920 AE 50 OÞ compared to that of the membrane system ð1286 AE 1 OÞ based on measurements using impedance spectroscopy. In both systems, it was observed that oxygen diffusion from the cathode chamber into the anode chamber was a factor in power generation. Nitrogen gas sparging, L-cysteine (a chemical oxygen scavenger), or suspended cells (biological oxygen scavenger) were used to limit the effects of gas diffusion into the anode chamber. Nitrogen gas sparging, for example, increased overall Coulombic efficiency (47% or 55%) compared to that obtained without gas sparging (19%). These results show that increasing power densities in MFCs will require reducing the internal resistance of the system, and that methods are needed to control the dissolved oxygen flux into the anode chamber in order to increase overall Coulombic efficiency. r

- by Shaoan Cheng
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- Water, Proton Exchange Membrane, Air pollution, Impedance Spectroscopy

- by Nathan Joos
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- Engineering, Proton Exchange Membrane, System Design, Water Management

This work constitutes detailed EIS (Electrochemical Impedance Spectroscopy) measurements on a PBIbased HT-PEM unit cell. By means of EIS the fuel cell is characterized in several modes of operation by varying the current density, temperature and the stoichiometry of the reactant gases. Using Equivalent Circuit (EC) modeling key parameters, such as the membrane resistance, charge transfer resistance and gas transfer resistance are identified, however the physical interpretation of the parameters derived from EC's are doubtful as discussed in this paper. The EC model proposed, which is a modified Randles circuit, provides a reasonably good fit at all the conditions tested. The measurements reveal that the cell temperature is an important parameter, which influences the cell performance significantly, especially the charge transfer resistance proved to be very temperature dependent. The transport of oxygen to the Oxygen Reduction Reaction (ORR) likewise has a substantial effect on the impedance spectra, results showed that the gas transfer resistance has an exponential-like dependency on the air stoichiometry. Based on the present results and results found in recent publications it is still not clear what exactly causes the distinctive low frequency loop occurring at oxygen starvation. Contrary to the oxygen transport, the transport of hydrogen to the Hydrogen Oxidation Reaction (HOR), in the stoichiometry range investigated in this study, shows no measurable change in the impedance data. Generally, this work is expected to provide a basis for future development of impedance-based fuel cell diagnostic systems for HT-PEM fuel cell.

- by Erik Schaltz
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- Engineering, Proton Exchange Membrane, Fuel Cell, Low Frequency
- by Mehmet Uzunoglu
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- Engineering, Power Electronics, Renewable Energy, Proton Exchange Membrane
- by Dennis Curtin
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- Engineering, Proton Exchange Membrane, Fuel Cell, Water Management

This paper presents the concept and the design of a hybrid renewable energy polygeneration microgrid along with its technical and economical evaluation. The energy of the sun and the wind is harvested by photovoltaics and a wind turbine. Besides that, the components of the microgrid include a battery bank, a Proton Exchange Membrane (PEM) fuel cell, a PEM electrolyzer, a metal hydride tank, a reverse osmosis desalination unit using energy recovery and a control system. The microgrid covers the electricity, transport and water needs and thus its products are power, hydrogen as transportation fuel and potable water through desalination. Hydrogen and the desalinated water also act as medium to long term seasonal storage. A design tool based on TRNSYS 16, GenOpt 2.0 and TRNOPT was developed using Particle Swarm Optimization method. The economic evaluation of the concept was based on the discounting cash flow approach. The Monte Carlo Simulation method was used in order to take uncertainty into account. A technically feasible polygeneration microgrid adapted to a small island is financially profitable with a probability of 90% for the present and 100% at the medium term.► Polygeneration of power, hydrogen and potable water through desalination in remote areas. ► Particle Swarm Optimization for the design of Polygeneration microgrid design with TRNSYS, GenOpt and TRNOPT. ► Economic evaluation with Monte Carlo simulation for the calculation of NPV distribution. ► Polygeneration microgrids are technically feasible and most likely financially profitable.

- by Stelios Rozakis and +2
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- Engineering, Economics, Renewable Energy, Hydrogen