The reorientation of benzonitrile on Platinum electrode probed by surface enhanced Raman spectroscopy

The adsorption and reorientation behavior of benzonitrile on an electrochemical roughened Pt electrode were studied by surface-enhanced Raman spectroscopy (SERS) over a wide potential range. The results revealed that benzonitrile was adsorbed on the surface in a vertical orientation through the nitrogen atom of CN group in the relative positive potential region (>−0.6 V), while the benzonitrile molecule changed its orientation with the negative movement of potential (<−0.8 V). In the hydrogen evolution region, the intensity of the Raman bands from the benzene ring and CN group decreased dramatically, and the frequency of CN red-shifted about 160 cm−1. It indicated that the benzonitrile was adsorbed on the Pt electrode in a flat orientation by interacting with the electrode surface via CN and/or benzene ring. A schematic model about the adsorption configurations of benzonitrile in different potential regions was proposed.