Electrochemical Detection of Magnetic Convection: Effect of High Magnetic Fields on O2/O2− Electrode Reaction in Acetonitrile

Yamada, Akifumi; Aogaki, Ryoichi

doi:10.1002/1521-4109(200110)13:14<1161::aid-elan1161>3.0.co;2-s

Cited by 12 publications

(6 citation statements)

References 11 publications

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“…The diffusion coefficient for O 2 ( D O 2 ) is found to be 2.2× 10 −5 cm 2 s −1 in 0.1 M TBAClO 4 and 2.1× 10 −5 cm 2 s −1 in 0.1 M TBAPF 6 . These values are very close to the previously reported values of 4.87× 10 −5 cm 2 s −1 in 0.9 M TEABF 4 and 2.07 × 10 −5 cm 2 s −1 in acetonitrile containing 0.1 M TEAP. , We also calculated the diffusion coefficients of oxygen using the Levich method for ClO 4 − (2.3 × 10 −5 cm 2 s −1 ) and PF 6 − (2.1 × 10 −5 cm 2 s −1 ). Again, the small difference in the diffusion coefficient values between both the Randles−Sevcik and the Levich equations may be ascribed to the fact that the Randles−Sevcik equation does not contain the term for mass transport control.…”

Section: Resultssupporting

confidence: 89%

Elucidating the Mechanism of Oxygen Reduction for Lithium-Air Battery Applications

Laoire¹,

Mukerjee²,

Abraham³

et al. 2009

J. Phys. Chem. C

642

668

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Unlocking the true energy capabilities of the lithium metal negative electrode in a lithium battery has until now been limited by the low capacity intercalation and conversion reactions at the positive electrodes. Abraham et al. (Abraham, K. M.; Jiang, Z. J. Electrochem. Soc. 1996, 143, 1-5) overcame this limitation by removing these electrodes and allowing lithium to react directly with oxygen in the atmosphere, forming the Li-air battery. The Li/O 2 battery redox couple has a theoretical specific energy of 5200 W h/kg and represents the ultimate, environmentally friendly electrochemical power source. In this work, we report for the first time the intimate role of electrolyte, in particular the role of ion conducting salts, in determining the reversibility and kinetics of oxygen reduction in nonaqueous electrolytes designed for such applications. Such fundamental understanding of this high energy density battery is crucial to harnessing its full energy potential. The kinetics and mechanisms of O 2 reduction in solutions of hexafluorophosphate of the general formula A + PF 6 -, where A ) tetrabutylammonium (TBA), K, Na, and Li, in acetonitrile are reported on glassy carbon electrodes using cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques. The results show that the cations in the electrolyte strongly influence the reduction mechanism of O 2 . Larger cations represented by TBA salts displayed reversible O 2 /O 2 -redox couple, in contrast to those containing the smaller Li (and other alkali metal) cations, where an irreversible one-electron reduction of O 2 to LiO 2 , and other alkali metal superoxides, is shown to occur as the first process. It was also found the LiO 2 formed initially decomposes to Li 2 O 2 . Electrochemical data support the view that alkali metal oxides formed via electrochemical and chemical reactions passivate the electrode surface, making the processes irreversible. The O 2 reduction mechanisms in the presence of the different cations have been supplemented by kinetic parameters determined from detailed analyses of the CV and RDE data. The Lewis acid characteristics of the cation appear to be crucial in determining the reversibility of the system. The results of this study are expected to contribute to the rapid development of the Li-air battery.

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Section: Resultssupporting

confidence: 89%

Elucidating the Mechanism of Oxygen Reduction for Lithium-Air Battery Applications

Laoire¹,

Mukerjee²,

Abraham³

et al. 2009

J. Phys. Chem. C

642

668

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show abstract

“…30%) is smaller than that in the two bioelectrocatalytic oxidative systems (reconstituted GOx/FAD-PQQ-system and LDH/NAD + -PQQ-integrated system). The magnetic effect on the electrochemical reduction of O 2 may originate from several possible mechanisms: The magnetohydrodynamic effect is possible assuming that the O 2 reduction on the electrode is at least partially limited by the mass-transport process . An additional effect of magnetic field on the electrochemical reduction of O 2 was discussed in the literature, and it originates from the paramagnetic properties of O 2 molecules. , Also, the O 2 solubility in water is increased in the presence of magnetic field, and this might further contribute to the enhancement of the bioelectrocatalytic process .…”

Section: Resultsmentioning

confidence: 99%

Magnetic Field Effects on Bioelectrocatalytic Reactions of Surface-Confined Enzyme Systems: Enhanced Performance of Biofuel Cells

2005

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The effect of a constant magnetic field on bioelectrocatalytic transformations of three different enzyme assemblies linked to electrodes is examined and correlated with a theoretical magnetohydrodynamic model. The systems consist of surface-reconstituted glucose oxidase (GOx), an integrated lactate dehydrogenase/nicotinamide/pyrroloquinoline quinone assembly (LDH/NAD+ -PQQ), and a cytochrome c/cytochrome oxidase system (Cyt c/COx) linked to the electrodes. Pronounced effects of a constant magnetic field applied parallel to the electrode surface are observed for the bioelectrocatalyzed oxidation of glucose and lactate by the GOx-electrode and LDH/NAD+ -PQQ-electrode, respectively. The enhancement of the bioelectrocatalytic processes correlates nicely with the magnetohydrodynamic model, and the limiting current densities (iL) relate to B1/3 (B = magnetic flux density) and to C4/3 (C* = bulk concentration of the substrate). A small magnetic field effect is observed for the Cyt c/COx-electrode, and its origin is still questionable. The effect of the constant magnetic field on the performance of biofuel cells with different configurations is examined. For the biofuel cell consisting of LDH/NAD+ -PQQ anode and Cyt c/COx cathode, a 3-fold increase in the power output was observed at an applied magnetic field of B = 0.92 T and external load of 1.2 kOhms.

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“…An example of an organic compound that can be captured in a magnetic field gradient after electrochemical conversion is nitrobenzene [80,[171][172][173][174]. It is also possible to draw paramagnetic oxygen close to an electrode backed by a magnetic field gradient and enhance the current in oxygen reduction reactions [175][176][177][178][179].…”

Section: Overview Of Experimental Observations Of Magnetically Induce...mentioning

confidence: 99%

Magnetic forces in paramagnetic fluids

Butcher¹,

Coey²

2022

J. Phys.: Condens. Matter

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An overview of the effect of a magnetic field gradient on fluids with linear magnetic susceptibilities is given. It is shown that two commonly encountered expressions, the magnetic field gradient force and the concentration gradient force for paramagnetic species in solution are equivalent for incompressible fluids. The magnetic field gradient and concentration gradient forces are approximations of the Kelvin force and Korteweg-Helmholtz force densities, respectively. The criterion for the appearance of magnetically induced convection is derived. Experimental work in which magnetically induced convection plays a role is reviewed.

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Electrochemical Detection of Magnetic Convection: Effect of High Magnetic Fields on O2/O2− Electrode Reaction in Acetonitrile

Cited by 12 publications

References 11 publications

Elucidating the Mechanism of Oxygen Reduction for Lithium-Air Battery Applications

Elucidating the Mechanism of Oxygen Reduction for Lithium-Air Battery Applications

Magnetic Field Effects on Bioelectrocatalytic Reactions of Surface-Confined Enzyme Systems: Enhanced Performance of Biofuel Cells

Magnetic forces in paramagnetic fluids

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