A combined surface-enhanced infrared and electrochemical kinetics study of hydrogen adsorption and evolution on a Pt electrode

The adsorption of hydrogen atoms on a polycrystalline Pt electrode was examined in acid by surface-enhanced infrared (IR) spectroscopy, and the IR data was quantitatively compared with the kinetics of hydrogen evolution reaction (HER). The Pt–H stretching vibration was observed around 2100 cm−1 in the H2 evolution potential range (E < 0.1 V vs. RHE). The current of HER was proportional to the square of the band intensity at 0.02 < E < 0.1 V, from which it was concluded that the adsorbed hydrogen atom is the reaction intermediate of HER and the combination of two adsorbed hydrogen atoms is rate-determining. At E < 0.02 V, on the other hand, an inconsistency was found between the IR and electrochemical measurements due to the supersaturation of H2 at the interface.