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

Yunika Nomura; Dai Inoue; Yutaka Moritomo

doi:10.1039/d2ra07886d

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

RSC Adv. 2023 Jan 27;13(6):3971-3975. doi: 10.1039/d2ra07886d. eCollection 2023 Jan 24.

Authors

Yunika Nomura¹, Dai Inoue¹, Yutaka Moritomo^{1

2

3}

Affiliations

¹ Graduate School of Pure & Applied Science, University of Tsukuba Tennodai 1-1-1 Tsukuba Ibaraki 305-8571 Japan moritomo.yutaka.gf@u.tsukba.ac.jp.
² Faculty of Pure & Applied Science, University of Tsukuba Tennodai 1-1-1 Tsukuba Ibaraki 305-8571 Japan.
³ Tsukuba Research Center for Energy Materials Science (TREMS), University of Tsukuba Tsukuba Ibaraki 305-8571 Japan.

Abstract

The electrochemical Seebeck coefficient (α = dV/dT; V and T are the redox potential and temperature, respectively) is important parameter for thermoelectric conversion. Here, we found that α 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 (ε) spectra revealed that the crossover is ascribed to the transformation of the dominant Fe³⁺ complex from [FeL₆]³⁺ (L is solvent molecule) to [FeCl₄]^-.