Effect of Dopants on the Adsorption of Carbon Dioxide on Ceria Surfaces

Abstract High‐surface‐area nanosized CeO 2 and M‐doped CeO 2 (M=Cu, La, Zr, and Mg) prepared by a surfactant‐templated method were tested for CO 2 adsorption. Cu, La, and Zr are doped into the lattice of CeO 2 , whereas Mg is dispersed on the CeO 2 surface. The doping of Cu and La into CeO 2 leads to an increase of the CO 2 adsorption capacity, whereas the doping of Zr has little or no effect. The addition of Mg causes a decrease of the CO 2 adsorption capacity at a low Mg content and a gradual increase at a higher content. The CO 2 adsorption capacity follows the sequence Cu‐CeO 2 >La‐CeO 2 >Zr‐CeO 2 ≈CeO 2 >Mg‐CeO 2 at low dopant contents, in line with the relative amount of defect sites in the samples. It is the defect sites on the surface, not in the bulk of CeO 2 , modified by the dopants that play the vital role in CO 2 chemisorption. The role of surface oxygen vacancies is further supported by an in situ IR spectroscopic study of the surface chemistry during CO 2 adsorption on the doped CeO 2 .