SERS STUDIES OF ELECTRODE ELECTROLYTE INTERFACIAL WATER PART II - LIBRATIONS OF WATER CORRELATED TO HYDROGEN EVOLUTION REACTION/

Electrode/electrolyte interfacial water is one of the most interesting systems studied by surface-enhanced Raman spectroscopy (SERS) in the past two decades, and is briefly reviewed. It has been shown that the SERS characteristics of water are very different from those of other s urface species. Strong libration bands and the abnormal enhancement of the bending mode of water on Cu and Ag electrodes have been observed in the hydrogen evolution reaction (HER) potential region (< -1.0 V vs . SCE). The observations may be attributed to the special interfacial structure of water molecules, which is in favor of the deprotonation o f water and mass transfer of the proton and the reaction product OH- f rom the surface to the bulk through the hydrogen bonding net during HE R. A new enhancement mechanism for SERS involving charge transfer (CT) from metal to water is suggested by the correlation of HER current de nsity and SERS band intensity. The generality of this CT enhancement i s briefly discussed. (C) 1998 John Wiley & Sons Ltd.