Control synthesis of CeO2 nanomaterials supported gold for catalytic oxidation of carbon monoxide

CeO2 show excellent performance in catalysis due to its oxygen vacancies, high oxygen storage capacity and easy conversation between Ce3+ and Ce4+ oxidation states. The ceria nano-materials with different morphologies were prepared with hydrothermal methods in the present work. It is found that the gold particles on ceria prepared via incipient wetness impregnation method are smaller and more uniform than those prepared via deposition-precipitation method (Applied Surface Science 2017, 416, 183-190). The incipient wetness impregnation method prepared samples also show better catalytic performance for CO oxidation than the samples prepared via deposition-precipitation method. Characterization results reveal that the small sizes as well as the oxidation states of the gold nanoparticles contribute to the higher activity than the deposition-precipitation samples. For the incipient wetness impregnation samples, the 0.5%Au/CeO2NT could reach 100% CO conversion at 70 degrees C, which shows much better activity and stability than the 0.5%Au/CeO(2)rod and 0.5%Au/CeO2NC. XPS results indicates that this is because the higher Ce3+/Ce4+ and Au delta+/Au-0 of 0.5%Au/CeO2NT than 0.5%Au/CeO(2)rod and 0.5%Au/CeO2NC, since the presence of a specific Au delta+-Ce3+ structure promotes the adsorption of molecular oxygen and further favors the oxidation of CO. In addition, the gold nanoparticle could grow into larger particles on the ceria nanocubes and leads to the deactivition of the catalysts. In contrast the ceria nanorod and nanotube supported catalysts show excellent stability. (C) 2017 Elsevier B.V. All rights reserved.