Temperature switch of electrochemical Seebeck coefficient of Fe2+/Fe3+via formation of [FeCl4]2-/[FeCl4]-

Abstract

The electrochemical Seebeck coefficient (a = dV/dT; V and T are the redox potential and temperature, respectively) is important parameter for thermoelectric conversion. Here, we found that a of Fe2+/Fe3+ in dimethyl sulfoxide (DMSO) with small amount of 19 M LiCl aqueous solution exhibits a crossover behavior from 1.4 mV K-1 (20 °C = T = 40 °C) to ˜0 mV K-1 (50 °C = T = 80 °C). The molar absorption (?) spectra revealed that the crossover is ascribed to the transformation of the dominant Fe3+ complex from [FeL6]3+ (L is solvent molecule) to [FeCl4]-