Abstract: The adsorption and orientation of pyridine on platinum electrode surface were studied by using cyclic voltammetry and in-situ FTIRreflection-absorption spectroscopy(SNIFTIRS). The experimental results obtained show that the adsorption of pyridine occurred over the whole potential range of -0.80～0.80 V(vs SCE). In the potential range of -0.80～0.20 V, pyridine rings were toproposed absorb in the direction perpendicular to the electrode surface in one or two different modes, while in the range of -0.20～0.8 V, the flat orientation was found to be predominant. The flat orientation of adsorption probably also weakened the ordering of water molecules at and near the electrode surface.

Key words: In-situ reflection-absorption spectroelectrochemisty, Adsorption and orientation of pyri-dine, Platinum electrode