CARBON-DIOXIDE CHEMISTRY ON CU(100)

The binding energy for CO2 adsorbed on Cu(100) has been determined by use of temperature programmed desorption and was found to increase with increasing coverage from 25 to 30 kJ mol-1. The presence of surface oxygen did not significantly increase the CO2 binding energy. High-resolution electron energy-loss spectra results indicate that the molecularly adsorbed CO2 lies flat on both surfaces and resembles gas phase CO2. The dissociative adsorption of CO2 on Cu(100) at a CO2 pressure of 990 mbar and a temperature range of 475-550 K has been investigated by x-ray photoelectron spectroscopy. The dissociative adsorption Of CO2 was found to have an activation energy of 93 +/- 5 kJ mol-1 and to have a sticking coefficient of 7.5 X 10(-12) at 500 K. The dissociative adsorption of CO2 and surface oxygen removal by CO reaches equilibrium under our experimental conditions. The heat of reaction was calculated to 70 +/- 4 kJ mol-1.