In-situ X-ray diffraction studies of Pt electrode/solution interfaces

Abstract

Changes in structure of Pt/surfaces due to a variety of electrochemical processes are determined using electrochemically modulated in-situ X-ray reflection diffraction. Oxidation leads to the formation of amorphous oxide layers and polarization in the double layer region at potentials negative to the pzc to an amorphous layer of Pt-atoms. Formation of strongly adsorbed hydrogen does not cause structural changes but weakly adsorbed hydrogen as well as the adsorption of CO coordinated to single surface Pt-atoms and to more than one surface atom leads to the formation of two types of incommensurate surface layer, one close packed and the other expanded. The two layers are present simultaneously and the dimensions of the expanded surface layer depend on the nature of the adsorbate. All structural changes have been found to be reversible.