Extracting the kinetic parameters of the hydrogen evolution reaction at Pt in acidic media by means of dynamic multi-frequency analysis

Herein, we use dynamic multi-frequency analysis (DMFA) to investigate the reaction kinetics of a paradigm electro-catalytic reaction, i.e. the hydrogen evolution reaction (HER) at polycrystalline Pt electrodes in acidic media. DMFA allows measuring dynamic impedance spectra under non-steady state conditions, as it is the case to avoid the formation of hydrogen bubbles. The extracted impedance spectra were fitted using electrical equivalent circuits (EECs) based on an analytical model, which took into account a Volmer-Tafel mechanism for hydrogen evolution. We found that the EECs based on this model can serve as suitable electrical analog in order to describe the physico-electrochemical processes that govern the different stages of the HER.