Импеданс реакции выделения водорода по механизму Фольмера-Гейровского при различной форме зависимости теплоты адсорбции водорода от степени заполнения

Abstract

The steady-state polarization curves and overpotential dependences of the equivalent circuit elements (R1, R2, C2) were calculated for the hydrogen evolution at nonlinear variation of the free energy of hydrogen adsorption DGadswith increasing coverage q. It was shown that the polarization curves depend weakly on the function g(q) = DGads/RT while the values of the Faradaic impedance parameters depend markedly on g(q). When DGads is coverage-dependent, the following differences from Langmuir adsorption are observed: (i) inductive behavior of impedance at small rate constant of the Heyrovsky reaction compared with rate constant of the Volmer reaction and at equal transfer coefficients of the steps; (ii) logR1–h curve is off parallel with logR2–h curve at high cathodic polarizations.