Formation of mixed (NO ads+CO ads)/(1×1) islands on the Pt(100)-(hex) surface

Abstract

The coadsorption of NO and CO on the reconstructed Pt(100)-(hex) surface at 300 K was studied by means of high-resolution electron energy-loss spectroscopy (HREELS). NO+CO coadsorption layers prepared in three different ways were investigated: (1) CO adsorption after coverage of the surface with NO ads/(1×1) islands; (2) NO adsorption after coverage of the surface with CO, which was mainly adsorbed on structural defects of the reconstructed (hex) phase (low coverage of CO ads); and (3) NO adsorption after coverage of the surface with CO ads/(1×1) islands (high coverage of CO ads). In all cases the strong mutual interaction between NO ads and CO ads molecules resulted in the formation of mixed (NO ads+CO ads)/(1×1) islands. The mixed islands of NO ads and CO ads covered unreconstructed (1×1) patches. The islands were separated from each other by either free (hex) phase or a region consisting of structural defects, which appeared during the course of a surface (hex)→(1×1) back-reconstruction. In the mixed (NO ads+CO ads)/(1×1) islands, it was found that structural defects were occupied preferentially by molecularly adsorbed CO.