Large Dimensional CeO2 Nanoflakes by Microwave-Assisted Synthesis: Lamellar Nano-Channels and Surface Oxygen Vacancies Promote Catalytic Activity

作者：Ding, Huihui; Yang, Jingxia^*; Ma, Shuyi; Yigit, Nevzat; Xu, Jingli; Rupprechter, Guenther; Wang, JinJie^*

来源：ChemCatChem, 2018, 10(18): 4100-4108.

DOI：10.1002/cctc.201800784

• Catalyst
• CeO2 nanoflakes
• CO oxidation
• Imine synthesis
• Lamellar structure

Large nano-structured flakes of CeO2 (20-80nm in thickness, up to 5.6m in diameter) were synthesized by a combination of microwave (MW), ultraviolet (UV) and ultrasound (US), with or without pressure (P). The CeO2 structures were systematically examined by XRD, SEM, N-2 sorption, HRTEM, XPS, Raman and H-2-TPR. The synthesized CeO2 nanoflakes were composed by 3.0-7.5nm nanoparticles with the (111) surface exposed, and laminated to nanoflakes with 3.42-3.85nm nano-channels in between. MW-assisting was beneficial to form a higher surface Ce3+/(Ce3++Ce4+) ratio and surface oxygen vacancies during short synthesis procedure. A Raman peak at 480cm(-1) correlating with bulk Ce3+ was detected. H-2-TPR found MW and MW+P had more surface Ce3+ (surface oxygen vacancies). CO oxidation and imine conversion proved that MW+P was the optimum condition to produce highly active CeO2 nanoflakes. The much better catalytic performance than CeO2 from solvothermal preparation, due to the larger channel gap (3.85nm),a higher Ce3+/(Ce3++Ce4+) ratio (32%) and more surface oxygen vacancies on the particles of the organized flake structures.

• 出版日期2018-9-20
• 单位上海工程技术大学