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

Abuzar Taheri, Douglas R. MacFarlane, Cristina Pozo-Gonzalo, Jennifer M. Pringle

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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.

Original languageEnglish
Pages (from-to)709-716
Number of pages8
JournalAustralian Journal of Chemistry
Issue number9
Publication statusPublished - 2 Aug 2019

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