Abstract: The in situ molecular-probe FTIRspectroscopy was employed in the present workto study the adsorption of CO and SCN^- on surfaces of dispersed Pt and Pd thin layers,which were deposited electrochemically on glassy carbon (denoted as Pt/GCand Pd/GC)uner voltanmmetric conditions. Abnormal IRfeatures of adsorption of COand SCN^- andPt/GCand Pd/GChave been observed for the first time. In comparison with IRfeatures ofadsorption of these molecules on smooth Pt and Pd electrodes, the abnormal IRfeaturesconsist of mainly the inversion of the direction of IRband and the enhancement of bandintensities. The enhancement factors were evaluated at 20 for linearly bonded COon the Pt/GCsurface anal at 26 for bridge bonded CO on the Pd/GCsurface. Nevertheless other spectralfeatures(the vibrational frequency, the Stark effects, etc.) are nearly the same as thoseobserved on smooth Pt and Pd electrodes, and no significant difference in IRfeatures presentedfor adsorption of solution species (CO₂, SCN^-) on the dispersed surfaces. The surfaceroughness of these dispersed electrodes was measured relatively small (1.6 for Pt/GCand 1.2for Pd/GC). The present study discovered an interesting IRproperty of dispersed metallicthin layers, and suggested that the in situ iRspectra of larger signal to noise ration may beobtained by employing the specially prepared Pt/GCand Pd/GCelectrodes.

Key words: Electrocatalysis, In situ IR reflection spectroscopy, Electrosorption