The Effect of Solvent on the Seebeck Coefficient and Thermocell Performance of Cobalt Bipyridyl and Iron Ferri/Ferrocyanide Redox Couples

2019 ◽  
Vol 72 (9) ◽  
pp. 709 ◽  
Author(s):  
Abuzar Taheri ◽  
Douglas R. MacFarlane ◽  
Cristina Pozo-Gonzalo ◽  
Jennifer M. Pringle
Keyword(s):  
Organic Solvent ◽  
Seebeck Coefficient ◽  
Mixed Solvent ◽  
Waste Heat ◽  
Redox Couple ◽  
Seebeck Coefficients ◽  
Effect Of Solvent ◽  
Redox Couples ◽  
Ligand Interactions ◽  
Solvent Systems

The conversion of thermal energy to electricity using thermoelectrochemical cells (thermocells) is a developing approach to harvesting waste heat. The performance of a thermocell is highly dependent on the solvent used in the electrolyte, but the interplay of the various solvent effects is not yet well understood. Here, using the redox couples [Co(bpy)3][BF4]2/3 (bpy=2,2′-bipyridyl) and (Et4N)3/(NH4)4Fe(CN)6, which have been designed to allow dissolution in different solvent systems (aqueous, non-aqueous, and mixed solvent), the effect of solvent on the Seebeck coefficient (Se) and cell performance was studied. The highest Se for a cobalt-based redox couple measured thus far is reported. Different trends in the Seebeck coefficients of the two redox couples as a function of the ratio of organic solvent to water were observed. The cobalt redox couple produced a more positive Se in organic solvent than in water, whereas addition of water to organic solvent resulted in a more negative Se for Fe(CN)6 3−/4−. UV-vis and IR investigations of the redox couples indicate that Se is affected by changes in solvent–ligand interactions in the different solvent systems.

scholarly journals High seebeck coefficient in middle-temperature thermocell with deep eutectic solvent

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Naura Fakhira Antariksa ◽  
Teppei Yamada ◽  
Nobuo Kimizuka
Keyword(s):  
Seebeck Coefficient ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Spectroscopic Analysis ◽  
Waste Heat ◽  
Choline Chloride ◽  
Deep Eutectic Solvent ◽  
Redox Couple ◽  
Strong Interactions ◽  
High Seebeck Coefficient

AbstractDeep eutectic solvent (DES) was applied to the solvent of thermocell and high Seebeck coefficient (Se) of the thermocell was achieved at high-temperatures operation. The Se of a redox couple of ferricyanide and ferrocyanide ([Fe(CN)6]3−/4−) reaches − 1.67 mV/K in a DES consisting of ethylene glycol and choline chloride. Spectroscopic analysis reveals that this is due to the strong interactions between the redox couple and the DES. Furthermore, the cell can operate over a wide temperature range of 135–165 °C. This result is a desired feature for waste-heat recovery applications.

scholarly journals Photosolvation of [Co(CN)6]3−, trans-[Cr(NH3)2(NCS)4]−, and trans-[Cr(en)2NCSF]+ in aqueous mixed solvent systems

1976 ◽  
Vol 54 (23) ◽  
pp. 3794-3799 ◽  
Author(s):  
Carl Fook Chow Wong ◽  
Alexander David Kirk
Keyword(s):  
Quantum Yield ◽  
Ethylene Glycol ◽  
Organic Solvent ◽  
Aqueous Solutions ◽  
Bulk Viscosity ◽  
Mixed Solvent ◽  
Spectrophotometric Analysis ◽  
Similar Data ◽  
Associative Model ◽  
Solvent Systems

Photosolvation of [Co(CN)6]3−(1), trans-[Cr(NH3)2(NCS)4]−(2) and trans-[Cr(en)2NCSF]+(3) has been studied in various water/methanol, ethanol, acetonitrile, ethylene glycol, glycerol, and acetone mixtures and in aqueous solutions of polyvinylpyrolidone. The quantum yield for thiocyanate loss from 3 was found to be fairly independent of solvent, while for thiocyanate loss from 2, large, and at higher concentrations of organic solvent, specific reductions of quantum yield were observed. The study of 1 using spectrophotometric analysis for [Co(CN)5H2O]2− yielded similar data to some in the literature, but the larger range of systems studied here did not support the reported reduction of quantum yield with bulk viscosity. Furthermore evidence from this and other work suggests that many of the observed quantum yield reductions are only apparent, based on a false assumption that the photosolvation is qualitatively the same in ail mixtures. The data are reinterpreted in terms of competitive solvation by both solvent components. It is argued that this study supports a dissociative model of reaction for 1, but an associative model for the chromium complexes 2 and 3.

Temperature dependence of the electrode potential of a cobalt-based redox couple in ionic liquid electrolytes for thermal energy harvesting

2016 ◽  
Vol 190 ◽  
pp. 205-218 ◽  
Author(s):  
Jiangjing He ◽  
Danah Al-Masri ◽  
Douglas R. MacFarlane ◽  
Jennifer M. Pringle
Keyword(s):  
Ionic Liquids ◽  
Waste Heat ◽  
Thermal Response ◽  
Thermodynamic Quantity ◽  
Redox System ◽  
Cell Performance ◽  
Redox Couple ◽  
Seebeck Coefficients ◽  
A Cell ◽  
Current Densities

Increasing the application of technologies for harvesting waste heat could make a significant contribution to sustainable energy production. Thermoelectrochemical cells are one such emerging technology, where the thermal response of a redox couple in an electrolyte is used to generate a potential difference across a cell when a temperature gradient exists. The unique physical properties of ionic liquids make them ideal for application as electrolytes in these devices. One of the keys to utilizing these media in efficient thermoelectrochemical cells is achieving high Seebeck coefficients, Se: the thermodynamic quantity that determines the magnitude of the voltage achieved per unit temperature difference. Here, we report the Se and cell performance of a cobalt-based redox couple in a range of different ionic liquids, to investigate the influence of the nature of the IL on the thermodynamics and cell performance of the redox system. The results reported include the highest Se to-date for an IL-based electrolyte. The effect of diluting the different ILs with propylene carbonate is also reported, which results in a significant increase in the output powers and current densities of the device.

DIELECTRIC CONSTANT AND SEEBECK COEFFICIENT FOR SEMICONDUCTORS: THERMODYNAMIC AND DFT STUDIES

2013 ◽  
Vol 12 (06) ◽  
pp. 1350057 ◽  
Author(s):  
HSIU-YA TASI ◽  
CHAOYUAN ZHU
Keyword(s):  
Boundary Condition ◽  
Dielectric Constant ◽  
Seebeck Coefficient ◽  
Gas Phase ◽  
Present Method ◽  
Dielectric Constants ◽  
Semiconductor Materials ◽  
Electronic Polarizability ◽  
Seebeck Coefficients ◽  
Good Agreement

Dielectric constants and Seebeck coefficients for semiconductor materials are studied by thermodynamic method plus ab initio quantum density functional theory (DFT). A single molecule which is formed in semiconductor material is treated in gas phase with molecular boundary condition and then electronic polarizability is directly calculated through Mulliken and atomic polar tensor (APT) density charges in the presence of the external electric field. This electronic polarizability can be converted to dielectric constant for solid material through the Clausius–Mossotti formula. Seebeck coefficient is first simulated in gas phase by thermodynamic method and then its value divided by its dielectric constant is regarded as Seebeck coefficient for solid materials. Furthermore, unit cell of semiconductor material is calculated with periodic boundary condition and its solid structure properties such as lattice constant and band gap are obtained. In this way, proper DFT function and basis set are selected to simulate electronic polarizability directly and Seebeck coefficient through chemical potential. Three semiconductor materials Mg 2 Si , β- FeSi 2 and SiGe are extensively tested by DFT method with B3LYP, BLYP and M05 functionals, and dielectric constants simulated by the present method are in good agreement with experimental values. Seebeck coefficients simulated by the present method are in reasonable good agreement with experiments and temperature dependence of Seebeck coefficients basically follows experimental results as well. The present method works much better than the conventional energy band structure theory for Seebeck coefficients of three semiconductors mentioned above. Simulation with periodic boundary condition can be generalized directly to treat with doped semiconductor in near future.

scholarly journals Effect of solvent composition on the critical micelle concentration of sodium deoxycholate in ethanol-water mixed solvent media

BIBECHANA ◽  
2012 ◽  
Vol 9 ◽  
pp. 63-68 ◽  
Author(s):  
Ajaya Bhattarai ◽  
Sujit Kumar Shah ◽  
Ashok Kumar Yadav ◽  
Janak Adhikari
Keyword(s):  
Critical Micelle Concentration ◽  
Precise Measurement ◽  
Mixed Solvent ◽  
Volume Fraction ◽  
Pure Water ◽  
Specific Conductivity ◽  
Sodium Deoxycholate ◽  
Solvent Composition ◽  
Effect Of Solvent

The precise measurement of the specific conductivity of sodium deoxycholate in pure water and ethanolwater mixed solvent media containing 0.10 and 0.20 volume fraction of ethanol at 303.15 K are reported. The concentration were varied from ~ 0.01 mol L-1 to ~ 0.0002 mol L-1.The conductivity of sodium deoxycholate decreases with the increase in the volume fraction of ethanol. The critical micelle concentration of sodium deoxycholate increases with the increase in the volume fraction of ethanol. DOI: http://dx.doi.org/10.3126/bibechana.v9i0.7176 BIBECHANA 9 (2013) 63-68

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