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Your search keyword '"Singh, Ramesh K."' showing total 139 results
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139 results on '"Singh, Ramesh K."'

6. Elucidating the degradation mechanisms of Pt-free anode anion-exchange membrane fuel cells after durability testing

Author

Douglin, John C., primary, Singh, Ramesh K., additional, Yang-Neyerlin, Ami C., additional, He, Cheng, additional, Yassin, Karam, additional, Miller, Hamish A., additional, Pagliaro, Maria V., additional, Capozzoli, Laura, additional, Carbo-Argibay, Enrique, additional, Brandon, Simon, additional, Ferreira, Paulo J., additional, Pivovar, Bryan S., additional, and Dekel, Dario R., additional

Published
2024
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25. CoO x -Fe 3 O 4 /N-rGO Oxygen Reduction Catalyst for Anion-Exchange Membrane Fuel Cells.

Author

Singh, Ramesh K., Douglin, John C., Jiang, Lanjie, Yassin, Karam, Brandon, Simon, and Dekel, Dario R.

Subjects
*ION-permeable membranes, *FUEL cells, *PLATINUM group, *OXYGEN reduction, *X-ray photoelectron spectroscopy, *CATALYSTS, *TRANSMISSION electron microscopy
Abstract

Platinum group metal (PGM)-free oxygen reduction reaction (ORR) catalysts are of utmost importance for the rapid development of anion-exchange membrane fuel cell (AEMFC) technology. In this work, we demonstrate the improved ORR performance and stability of Co and Fe oxide-decorated/N-doped reduced graphene oxide (CoOx-Fe3O4/N-rGO) prepared via a hydrothermal method at the low temperature of 150 °C. The catalysts were characterized thoroughly using transmission electron microscopy, high-angle annular dark field-scanning electron microscopy, X-ray diffraction, N2 physisorption, Raman spectroscopy, and X-ray photoelectron spectroscopy to obtain information about morphology, elemental distribution, phases, porosity, defects, and surface elemental compositions. Significant ORR activity improvement (130 mV@-1.5 mA cm−2) was achieved with this catalyst compared to the pristine graphene oxide, and the ORR limiting current was even 12%@0.5 V higher than the commercial Pt/C. The enhanced ORR activity of CoOx-Fe3O4/N-rGO was attributed to the uniform dispersion of Co, Fe, and N on reduced graphene oxide (rGO) sheets. Furthermore, ORR accelerated stress tests revealed excellent durability, suggesting that this material could be a promising and durable catalyst. With a cathode layer of the CoOx-Fe3O4/N-rGO catalyst, we achieved a peak power density of 676 mW cm−2 in an operando H2-O2 AEMFC. To the best of our knowledge, this is the highest reported power density per cathode catalyst mass in a reported PGM-free cathode catalyst. Finally, we quantified the various cell polarization losses as a function of cathode catalyst loadings to obtain insights for future work with AEMFCs based on this catalyst. The improvement in the AEMFC performance using CoOx-Fe3O4/N-rGO as a cathode catalyst can be attributed to the synergistic effects of (i) the high turnover frequency of the transition metals (Co and Fe) for ORR and (ii) the enhancement provided by N doping to the metal distribution and stability. [ABSTRACT FROM AUTHOR]

Published
2023
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27. Laser cleaning for rust removal on mild steel: An experimental study on surface characteristics

Author

Narayanan Vishnu, Singh Ramesh K, and Marla Deepak

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

Laser cleaning is a relatively new and promising industrial cleaning method. Despite its potential as an alternative to conventional de-rusting methods, very few studies have been done on rust removal. The current study is aimed at investigating experimentally the effect of various important laser parameters on properties of surface after laser processing. Rusted mild steel samples were irradiated with moving pulsed laser beam. Parameters like scan speed, number of passes, etc. were varied and the change in properties such as surface profile, roughness, hardness, etc. of the processed surface were observed along with depth of removal. The depth of removal was found to increase with an increase in laser power, and number of scans but decreased with an increase in scan speed. The surface got discoloured and deformed at lower speeds and higher powers. The surface roughness after processing hardly showed any variation with the initial roughness values before cleaning but depended on the scanning path of the laser. The microhardness values after laser processing varied with path traced by the laser beam which points to microstructure changes in the samples due to laser processing.

Published
2018
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30. High-Temperature Anion-Exchange Membrane Fuel Cells

Author

Douglin, John C., primary, Singh, Ramesh K., additional, Bsoul, Saja, additional, Li, Songlin, additional, Biemolt, Jasper, additional, Yan, Ning, additional, Rothenberg, Gadi, additional, Varcoe, John, additional, and Dekel, Dario R, additional

Published
2021
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38. Improved Hydrogen Oxidation Reaction Activity and Stability of Buried Metal-Oxide Electrocatalyst Interfaces

Author

Speck, Florian D., Ali, Farhan S. M., Kallio, Tanja, Cherevko, Serhiy, Paul, Michael T. Y., Singh, Ramesh K., Böhm, Thomas, Hofer, André, Kasian, Olga, Thiele, Simon, Bachmann, Julien, Dekel, Dario R., Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy, Electrochemical Energy Conversion, Technion – Israel Institute of Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Helmholtz-Zentrum Berlin GmbH, Department of Chemistry and Materials Science, Aalto-yliopisto, Aalto University, Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association, Aalto University School of Science and Technology [Aalto, Finland], Department of Chemistry (TECHNION), Israel Institute of Technology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), and European Project: 721065,CREATE

Subjects
ddc:540, [CHIM.CATA]Chemical Sciences/Catalysis, ComputingMilieux_MISCELLANEOUS
Abstract

openaire: EC/H2020/721065/EU//CREATE Various bifunctional metal-oxide composites have recently been proposed as advanced hydrogen oxidation reaction (HOR) electrocatalysts for anion-exchange membrane fuel cells (AEMFCs). It is postulated that metal and oxide are active sites for the adsorption of hydrogen/proton and hydroxide ions, respectively. Of particular interest are the so-called buried interfaces. To investigate processes governing activity and stability at such interfaces, we prepare model Pd and Pt electrocatalysts which are fully covered by thin CeOx films. We investigate how oxide thickness influences HOR activity and dissolution stability of the electrocatalysts. It is found that materials behave very differently and that only Pd exhibits an enhanced HOR activity, while both oxide-protected metals are more stable toward dissolution. A 10-fold decrease in dissolution and 15-fold increase in HOR exchange current density are demonstrated for the optimized Pd/CeOx composites in comparison to pure Pd. We assess the mechanism of the electrocatalytic improvement as well as the role of the protective oxide films in such systems through advanced electrochemical and physical analysis. It is highlighted that a uniform, semipermeable oxide layer with a maximized electrocatalyst-oxide interface is crucial to form HOR catalysts with improved activity and stability.

Published
2020

43. Synthesis of CeOx‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Author

Singh, Ramesh K., primary, Davydova, Elena S., additional, Douglin, John, additional, Godoy, Andres O., additional, Tan, Haiyan, additional, Bellini, Marco, additional, Allen, Bryan J., additional, Jankovic, Jasna, additional, Miller, Hamish A., additional, Alba‐Rubio, Ana C., additional, and Dekel, Dario R., additional

Published
2020
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50. Synthesis of CeOx‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells.

Author

Singh, Ramesh K., Davydova, Elena S., Douglin, John, Godoy, Andres O., Tan, Haiyan, Bellini, Marco, Allen, Bryan J., Jankovic, Jasna, Miller, Hamish A., Alba‐Rubio, Ana C., and Dekel, Dario R.

Subjects
*ION-permeable membranes, *SURFACE reactions, *PALLADIUM catalysts, *ELECTRON energy loss spectroscopy, *HYDROGEN oxidation, *FUEL cells, *SCANNING transmission electron microscopy
Abstract

Due to the sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline electrolytes, the development of more efficient HOR catalysts is essential for the next generation of anion‐exchange membrane fuel cells (AEMFCs). In this work, CeOx is selectively deposited onto carbon‐supported Pd nanoparticles by controlled surface reactions, aiming to enhance the homogenous distribution of CeOx and its preferential attachment to Pd nanoparticles, to achieve highly active CeOx‐Pd/C catalysts. The catalysts are characterized by inductively coupled plasma–atomic emission spectroscopy, X‐ray diffraction, high‐resolution transmission electron microscopy, scanning transmission electron microscopy (STEM), electron energy loss spectroscopy, and X‐ray photoelectron spectroscopy to confirm the bulk composition, phases present, morphology, elemental mapping, local oxidation, and surface chemical states, respectively. The intimate contact between Pd and CeOx is shown through high‐resolution STEM maps. The oxophilic nature of CeOx and its effect on Pd are probed by CO stripping. The interfacial contact area between CeOx and Pd nanoparticles is calculated for the first time and correlated to the electrochemical performance of the CeOx‐Pd/C catalysts. Highest recorded HOR specific exchange current (51.5 mA mg−1Pd) and H2–O2 AEMFC performance (peak power density of 1,169 mW cm−2 mgPd−1) are obtained with a CeOx‐Pd/C catalyst with Ce0.38/Pd bulk atomic ratio. [ABSTRACT FROM AUTHOR]

Published
2020
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