Volume effect of organic solvent on electrochemical Seebeck coefficient of [Fe(CN) <sub>6</sub> ] <sup>4−</sup> /[Fe(CN) <sub>6</sub> ] <sup>3−</sup> in water
Dai Inoue, Yuya Fukuzumi, Yutaka Moritomo
Abstract
Abstract A thermocell with use of the electrochemical Seebeck coefficient ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>α</mml:mi> <mml:mo>≡</mml:mo> <mml:mstyle displaystyle="false"> <mml:mfrac> <mml:mrow> <mml:mi mathvariant="italic">d</mml:mi> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="italic">d</mml:mi> <mml:mi>T</mml:mi> </mml:mrow> </mml:mfrac> </mml:mstyle> <mml:mo>;</mml:mo> </mml:math> E and T are the redox potential and temperature, respectively). is a promising energy-harvesting device. α is the key parameter that governs the thermal efficiency ( η ) of the thermocell. Here, we systematically investigated the variation (Δ α ) in α of a redox couple of [Fe(CN) 6 ] 4− /[Fe(CN) 6 ] 3− in water, by adding 9% organic solvent in molar ratio. We found that Δ α for 11 organic solvents well scale to the molar volume ( V ). The empirical volume effect is understood in terms of the replacement of water molecules with organic molecules depending on V .