An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Molecular ORR catalysts based on metallo-corrole with the smallest meso-substituent reported to d... more Molecular ORR catalysts based on metallo-corrole with the smallest meso-substituent reported to date, Co(iii)CF3-corrole, was synthesized and compared to the well-studied Co(iii)tpf-corrole when adsorbed on a high surface area carbon support.
Abstract The rise in interest in fuel cells’ technologies increased the number of researchers and... more Abstract The rise in interest in fuel cells’ technologies increased the number of researchers and publications in the field. The ultimate test of new materials in a lab setup would be in a membrane electrode assembly (MEA), operating under realistic operating conditions (temperature, backpressure, humidity, etc.). The fabrication of the MEA for polymer electrolyte fuel cells (PEFC) is known to greatly affect their performance. Although several good studies were conducted on different parameters in the MEA fabrication, mostly one at a time, there is no comprehensive work on all of the critical parameters required to optimize the fabrication procedure for high performance in one study. Since one parameter may affect another, it is important to optimize all of them together. In addition, the availability of commercial membranes, gas diffusion layers, ionomers and catalysts is constantly changing, and calling for revision of fabrication procedures at an increasing pace. In this work, five different parameters were examined in order to optimize the overall performance of PEFC MEAs: the method of applying the catalyst ink, the hot-press stage, addition of Nafion adlayer on top of the catalyst layer, the compression of the GDE, and finally, the membrane thickness, in order to optimize the full procedure for high performance. The MEAs were tested for several key features in the fuel cell's performance; including the time it takes for the cell to be “broken-in”, polarization curves, fuel crossover and charge transfer resistance. A clear optimum was achieved with the ultra-sonic sprayed catalyst ink, with the addition of the ionomer layer, and GDE compression of 43%, while the membrane thickness seems to be a bit less important.
As the interest in alkaline fuel cells (AFCs) rises, the development of new materials to increase... more As the interest in alkaline fuel cells (AFCs) rises, the development of new materials to increase their activity and lower their cost, the question of their durability has become critical. The durability testing protocols suggested by agencies such as the US DOE is limited to the study of platinum on carbon in acid. These protocols have become the generic testing protocols to all fuel cell catalysts but the they possess one significant flaw: they do not necessarily take into account the vulnerabilities of other types of catalysts. When studying the durability of fuel cells, one can conduct a constant lifetime test; however, this method is time-consuming and expensive. Instead of long-term measurements, the fuel cells industry along with government agencies such as the US-DOE and researchers develop protocols and perform accelerated stress tests (ASTs). ASTs are methods for determining the durability of the whole cell or a particular component in the fuel cell system in short periods...
The most active non-precious metal catalysts (NPMCs) for oxygen reduction (ORR) to date are the p... more The most active non-precious metal catalysts (NPMCs) for oxygen reduction (ORR) to date are the pyrolyzed catalysts, inspired from Heme-like complexes. These are usually composed of iron and/or cobalt coordinated by nitrogens, claimed to resemble the structure of porphyrins and phthalocynines, on the surface of a carbon support. Unfortunately, the exact structure of the catalytic sites remains a mystery and the solution for this conundrum seems be almost impossible. The advantages of using such catalysts are: (1) their high activity and (2) low price, which is derived from the cost of their precursors. The disadvantages are: (1) low durability compared to precious metal catalysts, and (2) their unknown structure, which limits their further improvement in order to obtain both the activity and durability benchmarks needed to become good alternatives for precious metals. One of the most promising options to resolve these issues is to find non-pyrolyzed molecular non-precious metal cata...
Four first row transition metal-based metal–organic-frameworks were synthesized in activated carb... more Four first row transition metal-based metal–organic-frameworks were synthesized in activated carbon, showing high electrocatalytic ORR activity with surprising metal-ion dependence.
Chemical communications (Cambridge, England), Jan 30, 2017
Four β-pyrrole-substituted cobalt(iii) corroles were studied as electrocatalysts for the oxygen r... more Four β-pyrrole-substituted cobalt(iii) corroles were studied as electrocatalysts for the oxygen reduction reaction. The results disclose high dependence of the corrole's performance on its substituents, but once adsorbed on a high surface area carbon, this effect vanishes, resulting in a better catalytic performance than most well-defined molecular electrocatalysts for this reaction.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Molecular ORR catalysts based on metallo-corrole with the smallest meso-substituent reported to d... more Molecular ORR catalysts based on metallo-corrole with the smallest meso-substituent reported to date, Co(iii)CF3-corrole, was synthesized and compared to the well-studied Co(iii)tpf-corrole when adsorbed on a high surface area carbon support.
Abstract The rise in interest in fuel cells’ technologies increased the number of researchers and... more Abstract The rise in interest in fuel cells’ technologies increased the number of researchers and publications in the field. The ultimate test of new materials in a lab setup would be in a membrane electrode assembly (MEA), operating under realistic operating conditions (temperature, backpressure, humidity, etc.). The fabrication of the MEA for polymer electrolyte fuel cells (PEFC) is known to greatly affect their performance. Although several good studies were conducted on different parameters in the MEA fabrication, mostly one at a time, there is no comprehensive work on all of the critical parameters required to optimize the fabrication procedure for high performance in one study. Since one parameter may affect another, it is important to optimize all of them together. In addition, the availability of commercial membranes, gas diffusion layers, ionomers and catalysts is constantly changing, and calling for revision of fabrication procedures at an increasing pace. In this work, five different parameters were examined in order to optimize the overall performance of PEFC MEAs: the method of applying the catalyst ink, the hot-press stage, addition of Nafion adlayer on top of the catalyst layer, the compression of the GDE, and finally, the membrane thickness, in order to optimize the full procedure for high performance. The MEAs were tested for several key features in the fuel cell's performance; including the time it takes for the cell to be “broken-in”, polarization curves, fuel crossover and charge transfer resistance. A clear optimum was achieved with the ultra-sonic sprayed catalyst ink, with the addition of the ionomer layer, and GDE compression of 43%, while the membrane thickness seems to be a bit less important.
As the interest in alkaline fuel cells (AFCs) rises, the development of new materials to increase... more As the interest in alkaline fuel cells (AFCs) rises, the development of new materials to increase their activity and lower their cost, the question of their durability has become critical. The durability testing protocols suggested by agencies such as the US DOE is limited to the study of platinum on carbon in acid. These protocols have become the generic testing protocols to all fuel cell catalysts but the they possess one significant flaw: they do not necessarily take into account the vulnerabilities of other types of catalysts. When studying the durability of fuel cells, one can conduct a constant lifetime test; however, this method is time-consuming and expensive. Instead of long-term measurements, the fuel cells industry along with government agencies such as the US-DOE and researchers develop protocols and perform accelerated stress tests (ASTs). ASTs are methods for determining the durability of the whole cell or a particular component in the fuel cell system in short periods...
The most active non-precious metal catalysts (NPMCs) for oxygen reduction (ORR) to date are the p... more The most active non-precious metal catalysts (NPMCs) for oxygen reduction (ORR) to date are the pyrolyzed catalysts, inspired from Heme-like complexes. These are usually composed of iron and/or cobalt coordinated by nitrogens, claimed to resemble the structure of porphyrins and phthalocynines, on the surface of a carbon support. Unfortunately, the exact structure of the catalytic sites remains a mystery and the solution for this conundrum seems be almost impossible. The advantages of using such catalysts are: (1) their high activity and (2) low price, which is derived from the cost of their precursors. The disadvantages are: (1) low durability compared to precious metal catalysts, and (2) their unknown structure, which limits their further improvement in order to obtain both the activity and durability benchmarks needed to become good alternatives for precious metals. One of the most promising options to resolve these issues is to find non-pyrolyzed molecular non-precious metal cata...
Four first row transition metal-based metal–organic-frameworks were synthesized in activated carb... more Four first row transition metal-based metal–organic-frameworks were synthesized in activated carbon, showing high electrocatalytic ORR activity with surprising metal-ion dependence.
Chemical communications (Cambridge, England), Jan 30, 2017
Four β-pyrrole-substituted cobalt(iii) corroles were studied as electrocatalysts for the oxygen r... more Four β-pyrrole-substituted cobalt(iii) corroles were studied as electrocatalysts for the oxygen reduction reaction. The results disclose high dependence of the corrole's performance on its substituents, but once adsorbed on a high surface area carbon, this effect vanishes, resulting in a better catalytic performance than most well-defined molecular electrocatalysts for this reaction.
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