乙二醇溶剂热合成的CeO2的可逆氧化还原性及CO2捕获性能

利用乙二醇的还原性，采用乙二醇溶剂热法制备了表面具有丰富氧空穴的CeO₂-GST纳米晶，对其进行了X射线衍射、透射电镜、X射线光电子能谱、原位H₂还原-O₂氧化循环和CO₂原位红外漫反射表征，并研究了其可逆氧化还原性及CO₂捕获性能. 结果表明，与CeO₂-nanorod和柠檬酸溶胶法合成的CeO₂-CA样品相比，CeO₂-GST纳米晶具有最好的可逆氧化还原性能和循环稳定性，同时在50 ℃下具有最好的CO₂吸附性能（149 μmol/g）. 利用原位红外漫反射光谱研究了CO₂在还原CeO₂表面的吸附情况，发现CO₂主要以双齿碳酸盐和桥连碳酸盐两种形式吸附在CeO₂表面，其中桥连碳酸盐物种不稳定，He吹扫可脱附. 此外，CO₂在CeO₂-nanorod上还会生成稳定的甲酸盐和单齿碳酸盐物种.

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

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 ℃ 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.