Frequency response of Gibbs free energy and enthalpy changes of electrochemical systems analyzed as thermometric transfer functions

Electron transfer reactions are usually accompanied by heat generated as a byproduct. This heat is the sum of reversible effects as the molar electrochemical Peltier heat and irreversible effects like overpotential and the Joule effect. These effects have been calculated by measuring temperature changes in the working electrode, using calorimetric and electrochemical techniques involving direct current. This work presents a theoretical-experimental strategy to calculate for the first time two new thermometric transfer functions: Gibbs free energy, Δ G(ω ) , and enthalpy changes, Δ H(ω ) . Electrochemical impedance spectroscopy, EIS, and other transfer functions, including variation of interfacial temperature VIT, molar electrochemical Peltier heat Π (ω ) , and entropy change Δ S(ω ) are used to develop the theoretical experimental strategy and calculated the two new thermometric transfer functions. The theoretical models for computing Δ G(ω ) and Δ H(ω ) were validated with previously experimental reported data of VIT, Π (ω ) and Δ S(ω ) for the ferrocyanide/ferricyanide electrochemical system. Nyquist and Bode diagrams for Δ G(ω ) and Δ H(ω ) are shown, and a brief discussion concerning their behavior is presented.