Electropolymerization ofo-phenylenediamine on Pt-electrode from aqueous acidic solution: Kinetic, mechanism, electrochemical studies and characterization of the polymer obtained

2009 ◽  
Vol 112 (6) ◽  
pp. 3695-3706 ◽  
Author(s):  
S. M. Sayyah ◽  
M. M. El-Deeb ◽  
S. M. Kamal ◽  
R. E. Azooz
Keyword(s):  
Acidic Solution ◽  
Kinetic Mechanism ◽  
Electrochemical Studies ◽  
Pt Electrode ◽  
Solution Kinetic ◽  
Aqueous Acidic Solution

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

scholarly journals Achieving highly efficient and selective cesium extraction using 1,3-di-octyloxycalix[4]arene-crown-6 in n-octanol based solvent system: experimental and DFT investigation

RSC Advances ◽  
2021 ◽  
Vol 11 (35) ◽  
pp. 21323-21331
Author(s):  
Kankan Patra ◽  
Biswajit Sadhu ◽  
Arijit Sengupta ◽  
C. B. Patil ◽  
R. K. Mishra ◽  
...  
Keyword(s):  
Fission Product ◽  
Acidic Solution ◽  
Solvent System ◽  
Selective Extraction ◽  
Separation Scheme ◽  
Highly Efficient ◽  
Aqueous Acidic Solution

Separation scheme was developed for selective extraction of long-lived fission product 137Cs using substituted calix crown 6 ether from aqueous acidic solution.

Kinetic Mechanism and Inhibitor Characterization of WNK1 Kinase

Biochemistry ◽  
2009 ◽  
Vol 48 (43) ◽  
pp. 10255-10266 ◽  
Author(s):  
Yukiko I. Yagi ◽  
Koichi Abe ◽  
Kazunori Ikebukuro ◽  
Koji Sode
Keyword(s):  
Kinetic Mechanism

scholarly journals Characterization of the Biosynthesis, Processing and Kinetic Mechanism of Action of the Enzyme Deficient in Mucopolysaccharidosis IIIC

PLoS ONE ◽  
2011 ◽  
Vol 6 (9) ◽  
pp. e24951 ◽  
Author(s):  
Xiaolian Fan ◽  
Ilona Tkachyova ◽  
Ankit Sinha ◽  
Brigitte Rigat ◽  
Don Mahuran
Keyword(s):  
Mechanism Of Action ◽  
Kinetic Mechanism ◽  
Enzyme Deficient

Heterologous expression of a serine carboxypeptidase-like acyltransferase and characterization of the kinetic mechanism

FEBS Journal ◽  
2008 ◽  
Vol 275 (4) ◽  
pp. 775-787 ◽  
Author(s):  
Felix Stehle ◽  
Milton T. Stubbs ◽  
Dieter Strack ◽  
Carsten Milkowski
Keyword(s):  
Heterologous Expression ◽  
Kinetic Mechanism ◽  
Serine Carboxypeptidase
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