Effect of oxygen vacancy sites on CO2 adsorption dynamics: The case of rutile (1 × 1)-TiO2 (1 1 0)

The adsorption of CO2 has been studied by molecular beam scattering on slightly and strongly reduced TiO2(1 1 0). The defect density has qualitatively been characterized by CO2 TDS. Two peaks are present in TDS, which can be assigned to CO2 adsorption on pristine and oxygen vacancy sites. Interestingly, the initial reactivity, S0, towards CO2 adsorption decreases with increasing defect density and increases with increasing oxygen preexposure. The latter is related to the vanishing of the defect structure in TDS. In contrast, hydrogen preexposure leads to a decrease in S0 as well as the intensity of both TDS peaks decrease in sympathy.