IN-SITU FTIR SPECTROSCOPIC INVESTIGATIONS OF ABNORMAL INFRARED PROPERTIES OF ABSORPTION OF CO AND SCN- ON DISPERSED PT AND PD SURFACES

The in situ molecular-probe FTIR spectroscopy was employed in the pres ent work to study the adsorption of CO and SCN-on surfaces of disperse d Pt and Pd thin layers, which were deposited electrochemically on gla ssy carbon (denoted as Pt/GC and Pd/GC) under voltanmmetric conditions , Abnormal IR features of adsorption of CO and SCN- and Pt/GC and Pd/G C have been observed for the first time, In comparison with IR feature s of adsorption of these molecules on smooth Pt and Pd electrodes, the abnormal IR features consist of mainly the inversion of the direction of IR band and the enhancement of band intensities, The enhancement f actors were evaluated at 20 for linearly bonded CO on the Pt/GC surfac e and at 26 for bridge bonded CO on the Pd/GC surface, Nevertheless ot her spectral features(the vibrational frequency, the Stark effects, et c.) are nearly the same as those observed on smooth Pt and Pd electrod es, and no significant difference in IR features presented for adsorpt ion of solution species (CO2, SCN-) on the dispersed surfaces, The sur face roughness of these dispersed electrodes was measured relatively s mall (1.6 for Pt/GC and 1.2 for Pd/GC), The present study discovered a n interesting IR property of dispersed metallic thin layers, and sugge sted that the in situ IR spectra of larger signal to noise ration may be obtained by employing the specially prepared Pt/GC and Pd/GC electr odes.