The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
A. John Appleby - One of the best experts on this subject based on the ideXlab platform.
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Effect of Sputtered Film of platinum on low platinum loading electrodes on electrode kinetics of oxygen reduction in proton exchange membrane fuel cells
Electrochimica Acta, 1993Co-Authors: Sanjeev Mukerjee, Supramaniam Srinivasan, A. John ApplebyAbstract:Localization of Pt electrocatalyst by sputter deposition of a thin Film (500 A) on the front surface of a fuel cell electrode containing a supported electrocatalyst (20% Pt/C, 0.4 mg cm−2 loading) has been known to exhibit higher fuel cell performance as compared to that on the electrode without the Sputtered Film. This study compares the electrode kinetic parameters, electrochemically active surface areas, activation energies and reaction orders for the oxygen reduction reaction (ORR) in the Sputtered and unSputtered electrodes in proton exchange membrane fuel cells as functions of temperature and pressure. Comparison of the cell performance at 5 atm and 95°C indicates an almost 4 fold improvement in ORR activity at 0.9 V vs. rhe and a similar 3.6 fold improvement in the exchange current densities. The increment in the electrochemically active surface area was about two fold, thereby indicating that factors beyond a surface area increment were responsible for the observed activity enhancement in the ORR. Evaluation of ORR electrode kinetics as a function of temperature indicated a lower activation energy for ORR on the Sputtered electrode, as compared to that on the unSputtered electrode. The reaction orders for ORR were, however, the same for both electrodes and were similar to previously obtained values at the Pt microelectrode/Nafion interface, thereby indicating no change in the rate determining step for ORR. This paper also presents the morphological characterization of the electrode/membrane interface using the SEM/EDAX technique, which clearly signifies the two types of Pt—unsupported and supported.
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Effect of Sputtered Film of platinum on low platinum loading electrodes on electrode kinetics of oxygen reduction in proton exchange membrane fuel cells
Electrochimica Acta, 1993Co-Authors: Sanjeev Mukerjee, Supramaniam Srinivasan, A. John ApplebyAbstract:Localization of Pt electrocatalyst by sputter deposition of a thin Film (500 A) on the front surface of a fuel cell electrode containing a supported electrocatalyst (20% Pt/C, 0.4 mg cm−2 loading) has been known to exhibit higher fuel cell performance as compared to that on the electrode without the Sputtered Film. This study compares the electrode kinetic parameters, electrochemically active surface areas, activation energies and reaction orders for the oxygen reduction reaction (ORR) in the Sputtered and unSputtered electrodes in proton exchange membrane fuel cells as functions of temperature and pressure. Comparison of the cell performance at 5 atm and 95°C indicates an almost 4 fold improvement in ORR activity at 0.9 V vs. rhe and a similar 3.6 fold improvement in the exchange current densities. The increment in the electrochemically active surface area was about two fold, thereby indicating that factors beyond a surface area increment were responsible for the observed activity enhancement in the ORR. Evaluation of ORR electrode kinetics as a function of temperature indicated a lower activation energy for ORR on the Sputtered electrode, as compared to that on the unSputtered electrode. The reaction orders for ORR were, however, the same for both electrodes and were similar to previously obtained values at the Pt microelectrode/Nafion interface, thereby indicating no change in the rate determining step for ORR. This paper also presents the morphological characterization of the electrode/membrane interface using the SEM/EDAX technique, which clearly signifies the two types of Pt—unsupported and supported.
Sanjeev Mukerjee - One of the best experts on this subject based on the ideXlab platform.
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Effect of Sputtered Film of platinum on low platinum loading electrodes on electrode kinetics of oxygen reduction in proton exchange membrane fuel cells
Electrochimica Acta, 1993Co-Authors: Sanjeev Mukerjee, Supramaniam Srinivasan, A. John ApplebyAbstract:Localization of Pt electrocatalyst by sputter deposition of a thin Film (500 A) on the front surface of a fuel cell electrode containing a supported electrocatalyst (20% Pt/C, 0.4 mg cm−2 loading) has been known to exhibit higher fuel cell performance as compared to that on the electrode without the Sputtered Film. This study compares the electrode kinetic parameters, electrochemically active surface areas, activation energies and reaction orders for the oxygen reduction reaction (ORR) in the Sputtered and unSputtered electrodes in proton exchange membrane fuel cells as functions of temperature and pressure. Comparison of the cell performance at 5 atm and 95°C indicates an almost 4 fold improvement in ORR activity at 0.9 V vs. rhe and a similar 3.6 fold improvement in the exchange current densities. The increment in the electrochemically active surface area was about two fold, thereby indicating that factors beyond a surface area increment were responsible for the observed activity enhancement in the ORR. Evaluation of ORR electrode kinetics as a function of temperature indicated a lower activation energy for ORR on the Sputtered electrode, as compared to that on the unSputtered electrode. The reaction orders for ORR were, however, the same for both electrodes and were similar to previously obtained values at the Pt microelectrode/Nafion interface, thereby indicating no change in the rate determining step for ORR. This paper also presents the morphological characterization of the electrode/membrane interface using the SEM/EDAX technique, which clearly signifies the two types of Pt—unsupported and supported.
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Effect of Sputtered Film of platinum on low platinum loading electrodes on electrode kinetics of oxygen reduction in proton exchange membrane fuel cells
Electrochimica Acta, 1993Co-Authors: Sanjeev Mukerjee, Supramaniam Srinivasan, A. John ApplebyAbstract:Localization of Pt electrocatalyst by sputter deposition of a thin Film (500 A) on the front surface of a fuel cell electrode containing a supported electrocatalyst (20% Pt/C, 0.4 mg cm−2 loading) has been known to exhibit higher fuel cell performance as compared to that on the electrode without the Sputtered Film. This study compares the electrode kinetic parameters, electrochemically active surface areas, activation energies and reaction orders for the oxygen reduction reaction (ORR) in the Sputtered and unSputtered electrodes in proton exchange membrane fuel cells as functions of temperature and pressure. Comparison of the cell performance at 5 atm and 95°C indicates an almost 4 fold improvement in ORR activity at 0.9 V vs. rhe and a similar 3.6 fold improvement in the exchange current densities. The increment in the electrochemically active surface area was about two fold, thereby indicating that factors beyond a surface area increment were responsible for the observed activity enhancement in the ORR. Evaluation of ORR electrode kinetics as a function of temperature indicated a lower activation energy for ORR on the Sputtered electrode, as compared to that on the unSputtered electrode. The reaction orders for ORR were, however, the same for both electrodes and were similar to previously obtained values at the Pt microelectrode/Nafion interface, thereby indicating no change in the rate determining step for ORR. This paper also presents the morphological characterization of the electrode/membrane interface using the SEM/EDAX technique, which clearly signifies the two types of Pt—unsupported and supported.
Supramaniam Srinivasan - One of the best experts on this subject based on the ideXlab platform.
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Effect of Sputtered Film of platinum on low platinum loading electrodes on electrode kinetics of oxygen reduction in proton exchange membrane fuel cells
Electrochimica Acta, 1993Co-Authors: Sanjeev Mukerjee, Supramaniam Srinivasan, A. John ApplebyAbstract:Localization of Pt electrocatalyst by sputter deposition of a thin Film (500 A) on the front surface of a fuel cell electrode containing a supported electrocatalyst (20% Pt/C, 0.4 mg cm−2 loading) has been known to exhibit higher fuel cell performance as compared to that on the electrode without the Sputtered Film. This study compares the electrode kinetic parameters, electrochemically active surface areas, activation energies and reaction orders for the oxygen reduction reaction (ORR) in the Sputtered and unSputtered electrodes in proton exchange membrane fuel cells as functions of temperature and pressure. Comparison of the cell performance at 5 atm and 95°C indicates an almost 4 fold improvement in ORR activity at 0.9 V vs. rhe and a similar 3.6 fold improvement in the exchange current densities. The increment in the electrochemically active surface area was about two fold, thereby indicating that factors beyond a surface area increment were responsible for the observed activity enhancement in the ORR. Evaluation of ORR electrode kinetics as a function of temperature indicated a lower activation energy for ORR on the Sputtered electrode, as compared to that on the unSputtered electrode. The reaction orders for ORR were, however, the same for both electrodes and were similar to previously obtained values at the Pt microelectrode/Nafion interface, thereby indicating no change in the rate determining step for ORR. This paper also presents the morphological characterization of the electrode/membrane interface using the SEM/EDAX technique, which clearly signifies the two types of Pt—unsupported and supported.
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Effect of Sputtered Film of platinum on low platinum loading electrodes on electrode kinetics of oxygen reduction in proton exchange membrane fuel cells
Electrochimica Acta, 1993Co-Authors: Sanjeev Mukerjee, Supramaniam Srinivasan, A. John ApplebyAbstract:Localization of Pt electrocatalyst by sputter deposition of a thin Film (500 A) on the front surface of a fuel cell electrode containing a supported electrocatalyst (20% Pt/C, 0.4 mg cm−2 loading) has been known to exhibit higher fuel cell performance as compared to that on the electrode without the Sputtered Film. This study compares the electrode kinetic parameters, electrochemically active surface areas, activation energies and reaction orders for the oxygen reduction reaction (ORR) in the Sputtered and unSputtered electrodes in proton exchange membrane fuel cells as functions of temperature and pressure. Comparison of the cell performance at 5 atm and 95°C indicates an almost 4 fold improvement in ORR activity at 0.9 V vs. rhe and a similar 3.6 fold improvement in the exchange current densities. The increment in the electrochemically active surface area was about two fold, thereby indicating that factors beyond a surface area increment were responsible for the observed activity enhancement in the ORR. Evaluation of ORR electrode kinetics as a function of temperature indicated a lower activation energy for ORR on the Sputtered electrode, as compared to that on the unSputtered electrode. The reaction orders for ORR were, however, the same for both electrodes and were similar to previously obtained values at the Pt microelectrode/Nafion interface, thereby indicating no change in the rate determining step for ORR. This paper also presents the morphological characterization of the electrode/membrane interface using the SEM/EDAX technique, which clearly signifies the two types of Pt—unsupported and supported.
Nowshad Amin - One of the best experts on this subject based on the ideXlab platform.
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growth and characterization of rf Sputtered zns thin Film deposited at various substrate temperatures for photovoltaic application
Applied Surface Science, 2015Co-Authors: P Chelvanathan, Yulisa Yusoff, Faiazul Haque, Md Akhtaruzzaman, M M Alam, Zeid A Alothman, M J Rashid, Kamaruzzaman Sopian, Nowshad AminAbstract:Abstract RF-Sputtered ZnS thin Film was grown under various substrate temperatures with the aim of investigating its effects on the structural, surface morphology and optical properties. Investigated substrate temperature in this study was in the range of 25 °C–300 °C and the structural and optical properties were investigated in order to elucidate the changes induced by the varying thermal energy during the growth process. Structural determination by XRD method indicates all Sputtered Films have cubic structure with (1 1 1) as the preferential orientation. However, higher substrate temperature up to 200 °C increases the Film's crystallinity and grain size evident by the increase in peak intensity. Slight peak shift indicates ZnS lattice undergoes strain relaxation process mediated through the increase in the lattice constant from 5.32 A to 5.40 A. SEM image of surface morphology clearly shows the evolution of grain growth in which Sputtered Film at 200 °C has the largest grains with distinct grain boundaries. Calculation from the obtained transmission spectra indicates optical band gap is in the range of 3.6–3.9 eV. Theoretical analysis in terms of lattice parameter between ZnS with several upcoming photovoltaic absorber layers shows that lattice matched ZnS buffer layer can be grown by varying the substrate temperature.
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annealing effect in structural and electrical properties of Sputtered mo thin Film
Applied Surface Science, 2015Co-Authors: P Chelvanathan, Yulisa Yusoff, Md Akhtaruzzaman, Kamaruzzaman Sopian, Nowshad Amin, Zaihasraf Zakaria, Manawwer Alam, M A AlghoulAbstract:Abstract In this study, the effects of vacuum annealing on the structural and electrical properties of DC-Sputtered molybdenum (Mo) thin Films have been investigated. Mo thin Films were deposited by DC sputtering and subsequently subjected to vacuum annealing in a tube furnace from 350 to 500 °C. Films that were deposited with different temperatures showed good adhesion with soda lime glass substrate after “tape testing”. X-ray diffraction (XRD) spectra have indicated existence of (1 1 0) and (2 1 1) orientations. However, I (1 1 0)/ I (2 1 1) peak intensity ratio decreased for all vacuum annealed Mo Films compared to as-Sputtered Films indicating change of preferential orientation. This suggests vacuum annealing can be employed to tailor the Mo thin Film atomic packing density of the plane parallel to the substrate. SEM images of surface morphology clearly show compact and dense triangular like grains for as-Sputtered Film, while annealed Films at 350 °C, 400 °C and 450 °C indicate rice-like grains. Stony grains with less uniformity were detected for Films annealed for 500 °C. Meanwhile, electrical resistivity is insensitive to the vacuum annealing condition as all Films showed more or less same resistivity in the range of 3 × 10 −5 –6 × 10 −5 Ω cm.
Fritz B. Prinz - One of the best experts on this subject based on the ideXlab platform.
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A sharp peak in the performance of Sputtered platinum fuel cells at ultra-low platinum loading
Journal of Power Sources, 2002Co-Authors: Ryan O'hayre, Sang Joon John Lee, Suk Won Cha, Fritz B. PrinzAbstract:Abstract Proton exchange membrane fuel cells were fabricated by direct sputter deposition of platinum on the surface of Nafion 117 membranes. A sharp spike in the performance of these Sputtered platinum fuel cells was observed at ultra-low platinum thickness values of 5–10 nm. Within this narrow thickness range, the power output capability of Sputtered platinum fuel cells is several orders of magnitude better than the performance produced by thinner or thicker coatings. The spike in performance is explained by rapid changes in the Sputtered Film microstructure at the nanometer thickness level. When the membrane surface is deliberately modified by abrasion prior to sputtering, this sharp peak is not seen. Instead, a broad plateau is observed, where the performance is insensitive to the amount of Sputtered platinum. This behavior stems from how surface roughening affects the Sputtered catalyst layer continuity. The performance of a sputter-deposited membrane with a platinum loading level of 0.04 mg/cm 2 is compared to a commercial membrane electrode assembly (MEA) with a platinum loading of 0.4 mg/cm 2 . The maximum power output of the Sputtered cell is three-fifths that of the commercial MEA, but uses one-tenth the platinum.