Redox properties and CO2 capture ability of CeO2 prepared by a glycol solvothermal method

Abstract

CeO2 nanocrystals with plentiful oxygen vacancies were synthesized by a glycol solvothermal method (CeO2-GST) using the strong reducibility of glycol. For comparison, CeO2 nanorods (CeO2-nanorods) and CeO2 nanoparticles (CeO2-CA) were also prepared. The samples were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, H2 reduction-O2 oxidation cycle experiments and in situ CO2 infrared spectroscopy. The CeO2-GST sample exposed mainly (111) facets with abundant Ce3+ ions on its surface, and it gave excellent reversible redox behavior and high oxygen storage capacity. After seven H2 reduction-O2 oxidation cycles, the oxygen storage capacity became stable. The CeO2-GST sample also had a high CO2 adsorption capacity of 149 μmol/g at 50 °C by forming bidentate and bridge carbonates on the CeO2 surface. These carbonate species were less stable than the unidentate carbonate, bicarbonate and formate species, thus adsorbed CO2 was released easily. On reduced CeO2 nanorod, CO2 formed the stable unidentate carbonate and formate species, which is unfavorable for the release of adsorbed CO2.