Combining thermogalvanic corrosion and thermogalvanic redox couples for improved electrochemical waste heat harvesting

• Thermoelectrochemistry of iodide/triiodide investigated.
• At stainless steel, both thermogalvanic redox and corrosion processes occur.
• Results in a Seebeck coefficient that decreases with increasing temperature.
• Maximum Seebeck of + 13.6 mV K− 1 was observed at ΔT = 10 °C.

Thermogalvanic (or thermoelectrochemical) systems can convert a temperature difference into an electrical current by exploiting the entropy change associated with a redox process. This work investigates coupling thermogalvanic redox processes with thermogalvanic corrosion. Ferri/ferrocyanide and iodide/triiodide redox couples were investigated at platinum and stainless steel electrodes. Dilute iodine displays a Seebeck coefficient of + 0.26 mV K− 1 at platinum electrodes and + 2.1 mV K− 1 at stainless steel electrodes. An apparent Seebeck coefficient of + 13.6 mV K− 1 could be achieved under optimal conditions. This is demonstrated to be due to a combination of the iodide/triiodide thermogalvanic redox couple and thermogalvanic iodine-induced corrosion of the stainless steel.

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