02097nas a2200277 4500008004100000022001400041245012500055210006900180260007400249300001200323490000700335520113600342653001901478653003801497653000801535653000801543653001001551100002101561700002301582700001501605700001401620700002201634700001801656700002201674856012301696 2008 eng d a0021-891X00a2(7-3) fractional factorial optimization of polybenzimidazole based membrane electrode assemblies for H-2/O-2 fuel cells0 a273 fractional factorial optimization of polybenzimidazole based aVAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDSbSPRINGERcMAY a583-5900 v383 a

We describe the usefulness of a statistical fractional factorial design to obtain consistent and reproducible behavior of a membrane-electrode-assembly (MEA) based on a phosphoric acid (PA) doped polybenzimidazole (PBI) membrane, which allows a H-2/O-2 fuel cell to operate above 150 degrees C. Different parameters involved during the MEA fabrication including the catalyst loading, amount of binder, processing conditions like temperature and compaction load and also the amount of carbon in the gas diffusion layers (GDL) have been systematically varied according to a 2(7-3) fractional factorial design and the data thus obtained have been analyzed using Yates's algorithm. The mean effects estimated in this way suggest the crucial role played by carbon loading in the gas diffusion layer, hot compaction temperature and the binder to catalyst ratio in the catalyst layer for enabling continuous performance. These statistically designed electrodes provide a maximum current density and power density of 1,800 mA cm(-2) and 280 mW cm(-2), respectively, at 160 degrees C using hydrogen and oxygen under ambient pressure.

10aCarbon loading10aFractional factorial optimization10aMEA10aPBI10aPEMFC1 aKannan, Ramaiyan1 aIslam, Md., Nazrul1 aRathod, D.1 aVijay, M.1 aKharul, Ulhas, K.1 aGhosh, P., C.1 aVijayamohanan, K. uhttps://library.ncl.res.in/content/27-3-fractional-factorial-optimization-polybenzimidazole-based-membrane-electrode-003339nas a2200253 4500008004100000022001400041245019100055210006900246260010600315300001400421490000700435520231200442653003202754653001002786653003002796653001702826653001002843100002402853700002502877700001902902700002202921700002402943856011802967 2010 eng d a0013-468600aPt-MoOx-carbon nanotube redox couple based electrocatalyst as a potential partner with polybenzimidazole membrane for high temperature polymer electrolyte membrane fuel cell applications0 aPtMoOxcarbon nanotube redox couple based electrocatalyst as a po aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAR a2878-28870 v553 a

A redox couple based electrocatalyst comprising of Pt-Multi Wall Carbon NanoTube (Pt-MWCNT) promoted with molybdenum oxide (MoOx, 2 < x < 3) nanoparticles was prepared. The objective was to effectively organize the Pt-MoOx interface on the smooth MWCNT surface to overcome the practical difficulties associated with establishing such interface with Pt dispersed on carbon morphologies possessing surface irregularities. The present study revealed the importance of stringent controlling of the additive level for maintaining a balanced bifunctional behavior of the catalyst combination through the synergistic effects by the components and the need of a proton conducting membrane operable at high temperature to get better output from the Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems. An indigenously developed polybenzimidazole (PBI) membrane was used to fabricate a membrane electrode assembly (MEA) as it can be operated at higher temperatures compared to that of Nafion membranes. MoOx additive level was carefully controlled by monitoring the active Pt area by cyclic voltammetry. All prepared electrocatalysts were characterized by using HRTEM, XRD and XPS to get information on dispersion and morphology, crystalinity and oxidation state of different elements, respectively. The system prepared with 5% MoOx addition with respect to Pt (hereafter Pt-MoOx(5%)-MWCNT) displayed balanced active Pt area and excellent oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) activities. Rotating Disk Electrode (ROE) system was extensively utilized to understand the ORR kinetics and the favorable role of MoOx as the promoter in the reaction. The kinetic current (j(k)) measured at 0.02 V vs. Hg/Hg2SO4 electrode from the Koutecky-Levich plots was 9 times higher and the apparent activation energy during single cell evaluation was 27 kJ/mol lower for the MoOx promoted system, compared to the system without the additive. A higher operating temperature significantly favored the cell performance by a combined effect of enhancement in proton conductivity of the PBI membrane and possible kinetic benefit by the well postulated oxygen spill over effect by the MoOx type systems in some combinations involving such systems. (C) 2010 Elsevier Ltd. All rights reserved.

10aMethanol oxidation reaction10aMWCNT10aoxygen reduction reaction10aPBI membrane10aPEMFC1 aVellacheri, Ranjith1 aUnni, SreeKuttan, M.1 aNahire, Sandip1 aKharul, Ulhas, K.1 aKurungot, Sreekumar uhttps://library.ncl.res.in/content/pt-moox-carbon-nanotube-redox-couple-based-electrocatalyst-potential-partner-002945nas a2200229 4500008004100000022001400041245010500055210006900160260001100229300001100240490000800251520217200259653002302431653001402454653001002468653002302478100002302501700002102524700001802545700002102563856013102584 2019 eng d a0009-250900aComprehensive analytical model for polarization curve of a PEM fuel cell and experimental validation0 aComprehensive analytical model for polarization curve of a PEM f cOCT 12 a96-1170 v2063 a

The kinetics of cathodic oxygen reduction reaction (ORR) in a proton exchange membrane fuel cell (PEMFC) is significantly modulated by the resistances for transport of reactants to the catalytic sites offered by different components of the fuel cell. This modulation governs the polarization curve of the PEMFC. Consequently, the various operating, geometric and material parameters of the fuel cell dictate the polarization curve. The effects of these parameters on the polarization curve over the entire range of current density, from zero to limiting current, can be predicted using detailed numerical simulations, which are however expensive. Analytical models, although simple can capture the essential details of physico-chemical processes occurring inside a PEMFC and are significantly inexpensive. In this article, we derive an analytical equation of the polarization curve which is valid over the entire range of current density. Specifically, the representative situation of a humidified low temperature PEMFC is considered wherein oxygen transport resistance in the cathode catalyst layer (CCL) is encountered at lower current density than proton transport resistance in the CCL. A novel experimental methodology is illustrated to confirm that this is indeed the case. Next, we elucidate a procedure to determine in-situ oxygen diffusion coefficients in the various domains of an operational PEMFC. Finally, it is shown that the analytical polarization curve predicted using these parameters is in excellent agreement with the experimental and numerically simulated polarization curves over the entire range of current density. The significance of this work is that the analytical model relates the performance of a PEMFC to all operating and geometric parameters as well as the average transport and kinetic properties of the materials used in its different components, without the need for computationally expensive numerical simulations. The model can therefore provide useful insights for enhancing the performance of PEMFC in different regimes of current density as well as for diagnostic purposes. (C) 2019 Elsevier Ltd. All rights reserved.

10aFuel cell equation10aModelling10aPEMFC10aPolarization curve1 aThosar, Aniket, U.1 aAgarwal, Harshal1 aGovarthan, S.1 aLele, Ashish, K. uhttps://library.ncl.res.in/content/comprehensive-analytical-model-polarization-curve-pem-fuel-cell-and-experimental-validation03106nas a2200241 4500008004100000022001400041245014800055210006900203260000900272300001600281490000700297520225700304653002402561653003102585653000802616653001002624653002102634653001602655100002102671700001802692700002402710856013002734 2023 eng d a1944-824400aMicroporous 3D-structured hierarchically entangled graphene-supported Pt3Co alloy catalyst for PEMFC application with process-friendly features0 aMicroporous 3Dstructured hierarchically entangled graphenesuppor cJUN  a28023-280350 v153 a

To improve the oxygen reduction reaction(ORR) performance in aproton-exchange membrane fuel cell (PEMFC) cathode with respect tomass activity and durability, a suitable electrocatalyst design strategyis essentially needed. Here, we have prepared a sub-three nm-sizedplatinum (Pt)-cobalt (Co) alloy (Pt3Co)-supportedN-doped microporous 3D graphene (Pt3Co/pNEGF) by usingthe polyol synthesis method. A microwave-assisted synthesis methodwas employed to prepare the catalyst based on the 3D porous carbonsupport with a large pore volume and dense micro-/mesoporous surfaces.The ORR performance of Pt3Co/pNEGF closely matches withthe state-of-the-art commercial Pt/C catalyst in0.1 M HClO4, with a small overpotential of 10 mV. The 3Dmicroporous structure of the N-doped graphene significantly improvesthe mass transport of the reactant and thus the overall ORR performance.As a result of the lower loading of Pt in Pt3Co/pNEGF ascompared to that in Pt/C, the alloy catalyst achieved 1.5 times highermass activity than Pt/C. After 10,000 cycles, the difference in theelectrochemically active surface area (ECSA) and half-wave potential(E (1/2)) of Pt3Co/pNEGF is foundto be 5 m(2) g(Pt) (-1) (Delta ECSA)and 24 mV (Delta E (1/2)), whereas, forPt/C, these values are 9 m(2) g(Pt) (-1) and 32 mV, respectively. Finally, in a realistic perspective, single-celltesting of a membrane electrode assembly (MEA) was made by sandwichingthe Pt3Co/pNEGF-coated gas diffusion layers as the cathodedisplayed a maximum power density of 800 mW cm(-2) under H-2-O-2 feed conditions with aclear indication of helping the system in the mass-transfer region(i.e., the high current dragging condition). The nature of the I-V polarization shows a progressivelylower slope in this region of the polarization plot compared to asimilar system made from its Pt/C counterpart and a significantlyimproved performance throughout the polarization region in the caseof the system made from the Pt3Co/NEGF catalyst (withoutthe microwave treatment) counterpart. These results validate the betterprocess friendliness of Pt3Co/pNEGF as a PEMFC electrode-specificcatalyst owing to its unique texture with 3D architecture and well-definedporosity with better structural endurance.

10amicrowave synthesis10aN-doped porous 3D graphene10aORR10aPEMFC10apolyol synthesis10aPt3Co alloy1 aManna, Narugopal1 aSingh, Mayank1 aKurungot, Sreekumar uhttps://library.ncl.res.in/content/microporous-3d-structured-hierarchically-entangled-graphene-supported-pt3co-alloy-catalyst