A model for understanding the temperature change of an alternate hot and cold micro-band graphite electrode

Abstract A model is established for understanding the temperature change of an alternate hot and cold micro-band graphite electrode. It consists of two symmetrically placed thermoelectric coolers with an embedded graphite sheet as interlayer. By measuring the open circuit behaviors of a standard redox couple, the electrode surface temperature can be detected. And the electrode surface temperature can be regulated from 40 °C to − 10 °C in aqueous solution without freezing. The model is described as Qh  =  γ h Δ T , Qc  =  γ c Δ T , where the temperature change (Δ T ) of electrode surface is assumed to be proportional to power of heating ( Q h ) or cooling ( Q c ). In addition, the diffusion activation energy of ferricyanide ion is firstly achieved by extending the temperature range from above zero degree down to the supercooled temperature (− 10 °C) with this specially designed electrode. Diffusion coefficient of ferricyanide ion is ca. 0.22 × 10 − 5  cm 2  s − 1 at − 10 °C, and activation energy is 23.2 kJ mol − 1 . The experimental data are consistent with data obtained by Stokes–Einstein equation for the determination of diffusion coefficient and activation energy.