Extending surface Raman spectroscopic studies to transition metals for practical applications: II. Hydrogen adsorption at platinum electrodes

Hydrogen adsorption at platinum electrodes in acidic solution is investigated by confocal microprobe Raman spectroscopy. Vibrations for on-top adsorbed hydrogen against platinum surface at c. 2088 cm −1 are observed in the overpotential deposition (OPD) region of hydrogen evolution. With the negative change in potential, there is a red shift of Pt–H vibrational frequency. In the underpotential deposition (UPD) region, only a very weak and broad band is discernible when the surface hydrogens are saturated. This indicates that the nature and the bonding configuration of the surface hydrogen are remarkably different in the UPD and OPD regions. Several factors, including the applied potential, hydrogen surface coverage, interactions with electrolyte ions and water molecules, are briefly discussed in terms of their influence on the observed spectroscopic properties.