IRAS Study of CO Adsorption on Mixed Co and S Overlayers on Mo ( ll 0 )

Infrared reflection absorption spectroscopy (IRAS) was used to study the adsorption of carbon monoxide on mixed S and Co overlayers on a Mo(l10) surface. The results of this study indicate that there is a migration/ segregation of the adatoms into 2-D and 3-D islands and that the different domains are distinguishable by the stretching frequency of the adsorbed CO. Clean Mo(l10) as well as sulfided Co, (8x2)Co, p(2X2)S, and ~ ( 2 x 2 ) s domains on the Mo( 110) surface are all observable. In addition, sulfur was seen to act as both a site blocker and electron-withdrawing agent on these surfaces. Finally, data obtained in this study suggest that the active adsorption site in a Co-MoS2 catalyst could be a Co-promoted M0-S site.