Scaling Relation Between Electrochemical Seebeck Coefficient For Fe2+/Fe3+ In Organic Solvent And Its Viscosity

The temperature coefficient alpha (= dV/dT) of the redox potential (V) in a redox system, or so-called electrochemical Seebeck coefficient, is a key parameter for thermal energy harvesting. We systematically investigated alpha for Fe2+/Fe3+ in 16 organic solvents, i.e., 8 protic and 8 aprotic solvents. We found that alpha shows remarkable solvent dependence and is distributed from 0.14 mV/K for glycerin to 3.60 mV/K for acetone. We further found a scaling relation between alpha and viscosity (eta) of the solvent as alpha proportional to eta(-0.4). We will discuss solvent dependence of a and the scaling relation in terms of the configuration entropy of the solvent molecules.