Impedance study of hydrogen evolution from solid tetrabutylammonium hydroxide hydrate

The hydrogen evolution (HER) from solid tetrabutylammonium hydroxide hydrate (C4H9)4NOH·30H2O (TBAOH30) has been studied at Au electrode in temperature range 220–305 K by electrochemical impedance spectroscopy (EIS). ape of impedance spectra obtained at negative overpotentials depends on temperature. The best-fit equivalent circuit is composed of bulk resistance being in series with the constant phase element (CPE), representing impedance of electrode–electrolyte interface, parallel to charge transfer resistance. This indicates that the kinetics of the interfacial reaction is the rate-determining step. The linear Arrhenius type plot of the reciprocal of the charge transfer resistance was obtained at selected overpotentials. The value of the activation energy is equal 0.63 eV and it is larger than that of conduction process. The reasons of this difference is discussed.