氧化铈
材料科学
铈
X射线光电子能谱
选区衍射
氧化物
透射电子显微镜
纳米颗粒
氧化态
化学工程
扫描电子显微镜
纳米纤维
纳米技术
金属
冶金
复合材料
工程类
作者
R.V. Lakshmi,Parthasarathi Bera,Kamalesh Pal,Vijay Alwera,Arup Gayen,Tapas Kumar Mandal,S.T. Aruna
标识
DOI:10.1166/jnn.2021.18988
摘要
Cerium oxide particles with different morphologies, namely nanoparticles, nanofibers, nanocubes, and rice grains have been prepared by simple chemical routes. The shape and size of the synthesized morphologies have been studied using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) and selected area electron diffraction (SAED) techniques have been used to determine their crystal phases. Both nanoparticles and nanocubes of cerium oxide exclusively crystallize in fluorite structure of CeO 2 as observed in XRD patterns, whereas nanofibers and rice grains are characterized by the presence of CeO 2 , Ce 2 O 3 , and Ce(OH) 3 phases. X-ray photoelectron spectroscopy (XPS) has been employed to evaluate Ce species present in the different cerium oxide morphologies and to estimate their relative surface concentrations. As evident from Ce 3d core level spectra cerium oxide nanoparticles and nanocubes are basically CeO 2 having Ce in the +4 oxidation state along with some amount of Ce 3+ species. In contrast, Ce is in +3 oxidation state on its surface in cerium oxide nanofibers and rice grains that contain intermediate phases like Ce 2 O 3 and Ce(OH) 3 as endorsed by XRD patterns. CO oxidation has been carried out over these cerium oxide morphologies and among all morphologies lowest temperature CO oxidation has been demonstrated by the nanocube morphology.
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