Surface-enhanced infrared absorption spectroscopy using chemically deposited Pd thin film electrodes

We report here the first observation of surface-enhanced infrared absorption (SEIRA) on chemically deposited Pd on Si. So far, SEIRA-active Pd films have been prepared by electrochemical deposition of Pd on SEIRA-active metals. When such films are used in solution to examine electrochemical reactions, however, Pd is dissolved into the solution at high potentials. The dissolution of Pd exposes the underlying metal surface and obscures the analysis of reactions on Pd surface. This problem can be removed by chemically depositing Pd directly onto the Si substrate. The strong SEIRAS effect of the chemically deposited Pd was demonstrated for CO adsorbed on the surface in acid under potential control. The dissolution of the Si substrate under anodic polarization is also discussed.