Large Dimensional CeO2 Nanoflakes by Microwave-Assisted Synthesis: Lamellar Nano-Channels and Surface Oxygen Vacancies Promote Catalytic Activity
Large Dimensional CeO2 Nanoflakes by Microwave-Assisted Synthesis: Lamellar Nano-Channels and Surface Oxygen Vacancies Promote Catalytic Activity
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微波辅助合成大尺寸 CeO2 纳米片：层状纳米通道和表面氧空位促进催化活性
DOI：
10.1002/cctc.201800784
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发表时间：
2018-09-20
期刊：
影响因子：
4.5
通讯作者：
Wang, JinJie
中科院分区：
文献类型：
--
作者：
Ding, Huihui;Yang, Jingxia;Wang, JinJie
采用微波（MW）、紫外（UV）和超声波（US）相结合的方法，在有压力（P）和无压力（P）的条件下合成了大尺寸的纳米CeO_2薄片（厚度为20- 80 nm，直径达5.6 μ m）。采用XRD、SEM、N2吸附、HRTEM、XPS、拉曼和H-2-TPR等手段对CeO 2的结构进行了系统的表征。所合成的CeO 2纳米片由3.0-7.5nm的纳米颗粒组成，其（111）面暴露，并且层压成纳米片，纳米片之间具有3.42-3.85nm的纳米通道。微波辅助有利于在短时间内形成较高的表面Ce 3 +/（Ce 3 ++ Ce 4+）比和表面氧空位。在480 cm（-1）处检测到一个与体相Ce ~（3+）相关的拉曼峰。H-2-TPR发现MW和MW+P具有更多的表面Ce 3+（表面氧空位）。CO氧化和亚胺转化证明MW+P是制备高活性CeO 2纳米片的最佳条件。与溶剂热法制备的CeO_2相比，具有更大的孔道间隙（3.85nm）、更高的Ce ~（3+）/（Ce ~（3 ++）+Ce ~（4+））比（32%）和更多的表面氧空位，从而提高了催化剂的催化性能。
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.