[Zurück]

H. Ding, J. Yang, S. Ma, N. Yigit, J. Xu, G. Rupprechter, J. Wang:
"Large Dimensional CeO₂ Nanoflakes by Microwave-Assisted Synthesis: Lamellar Nano-Channels and Surface Oxygen Vacancies Promote Catalytic Activity";
ChemCatChem, 10 (2018), 10; S. 1 - 10.

Large nano‐structured flakes of CeO₂ (20-80 nm in thickness, up to 5.6 μm 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, N2 sorption, HRTEM, XPS, Raman and H₂‐TPR. The synthesized CeO₂ nanoflakes were composed by 3.0-7.5 nm nanoparticles with the (111) surface exposed, and laminated to nanoflakes with 3.42-3.85 nm 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 480 cm⁻¹ correlating with bulk Ce³⁺ was detected. H₂‐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 (3.85 nm),a higher Ce³⁺/(Ce³⁺+Ce⁴⁺) ratio (32 %) and more surface oxygen vacancies on the particles of the organized flake structures.

http://dx.doi.org/10.1002/cctc.201800784

https://publik.tuwien.ac.at/files/publik_271450.pdf