Adsorption of CO2 on pristine Zn-ZnO(0Â 0Â 0Â 1) and defected Zn-ZnO(0Â 0Â 0Â 1): A thermal desorption spectroscopy study

Adsorption of CO2 at 90 K on the Zn-terminated surface of ZnO leads to the detection of two peaks in thermal desorption spectroscopy (TDS) curves with desorption temperatures of 125 K and 170 K that shift to lower temperatures with coverage. These structures can be assigned to adsorption on pristine and intrinsic defect sites, respectively, of the surface with binding energies of 34.4 kJ/mol and 43.6 kJ/mol (ν = 1 × 1013 1/s). Data obtained from ion sputtered surfaces support further the assignment of these TDS peaks. The surfaces have been characterized by low energy electron diffraction and Auger electron spectroscopy. Additionally, TDS curves of n-butane have been collected, mainly as a test of the experiment setup. Multilayer and monolayer desorption peaks can be detected in agreement with studies on metal surfaces.