REACTION OF CO2 H2 ON K-CU(100) - RAIRS STUDIES AT ULTRAHIGH-VACUUM AND HIGHER PRESSURES

The reaction of CO2/H-2 on clean and potassium dosed Cu(100) was inves tigated by in situ RAIRS using a high pressure gas cell. For clean Cu( 100), exposure to 120 torr of CO2/H-2 mixture in the RAIRS cell from 2 5-degrees-C to 200-degrees-C resulted in no clearly resolvable RAIRS b ands. The result indicates that under the conditions used, the coverag e of formate must be very low. A K predosed Cu(100) surface was expose d to CO2/H2 in the RAIRS cell at 120 torr. At temperatures lower than 70-degrees-C, weak RAIRS features were observed, the most prominent be ing at approximately 1600 cm-1. At temperatures above 70-degrees-C, a RAIRS band was observed at approximately 1550 cm-1 with the band at 16 00 cm-1 disappearing. CO2 adsorption on N2O oxidized K/Cu(100) surface s also produced a RAIRS band at approximately 1545-1550 cm-1, suggesti ng that the surface was oxidized in CO2/H-2 at elevated temperatures a nd reacted with CO2 to form a carbonate species.