Electrochemical Peltier heats of anodic process for Fe(CN)63-/Fe (CN)64- system

The thermo-electrochemical technique was applied to study the electrochemical Peltier heat of electrode reaction. In this experiment, a precision system for thermo-electrochemical measurements with controlled temperature of ±0.001 K was set up, which consists of SRC-100 solution isoperibol calorimeter and an electrochemical workstation. A thermo-sensitive resistor was directly attached to the surface of working electrode to measure the change in potential signal due to temperature change of electrode. The curves of the electrode potential and temperature change against time for equal molar ratio of Fe(CN)63-/Fe(CN)64- couple with 5 sets of different concentrations were obtained under the condition of various constant-current polarizations. Using the thermo-electrochemical method for data-processing, the electrochemical Peltier heat of anodic process of Fe(CN)63-/Fe(CN)64- couple under various concentrations at 298.15 K are determined as 41.51 kJ/mol (0.075 mol/L), 43.48 kJ/mol (0.10 mol/L), 46.95 kJ/mol (0.15 mol/L), 50.77 kJ/mol (0.20 mol/L)and 54.81 kJ/mol (0.25 mol/L), respectively. The entropy change derived from these Peltier heat for the standard hydrogen electrode on absolute scale at this temperature is also given.