Control of oxygen vacancies and Ce+3 concentrations in doped ceria nanoparticles via the selection of lanthanide element
Control of oxygen vacancies and Ce+3 concentrations in doped ceria nanoparticles via the selection of lanthanide element
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DOI：
10.1007/s11051-012-1173-1
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发表时间：
2012-10-01
影响因子：
2.5
通讯作者：
Jain, N.
中科院分区：
文献类型：
--
作者：
Shehata, N.;Meehan, K.;Jain, N.
本文研究了与氧空位具有正缔合能的镧系元素钐、钕和负缔合能的元素钬、铒对铈离子化状态的影响，进而对掺杂氧化铈纳米颗粒中氧空位浓度的影响。使用透射电子显微镜、X射线衍射仪、光学吸收光谱和荧光光谱对使用化学沉淀法合成的掺杂和未掺杂的二氧化铈纳米颗粒进行结构和光学表征。据推断，负缔合能掺杂剂降低了Ce+4到Ce+3的转化，因此，抑制了氧空位，这通过观察到的允许直接带隙的增加、积分荧光强度的降低以及掺杂纳米颗粒的尺寸的增加来证明。当使用正缔合掺杂剂时，得到相反的趋势。可以得出结论，决定因素是否镧系元素掺杂剂在氧化铈纳米颗粒中作为生成剂或清除剂的氧空位是元素和氧空位之间的缔合能的符号。定制铈的电离状态和氧化铈中的氧空位浓度的能力在广泛的领域中具有应用，所述领域包括催化、生物医学、电子学和环境传感。
The effect of lanthanides that have positive association energies with oxygen vacancies, such as samarium and neodymium, and the elements with negative association energies, such as holmium and erbium, on ionization state of cerium and, consequentially, the oxygen vacancy concentration in doped ceria nanoparticles are investigated in this article. Structural and optical characterizations of the doped and undoped ceria nanoparticles, synthesized using chemical precipitation, are carried out using transmission electron microscopy, X-ray diffractometry, optical absorption spectroscopy, and fluorescence spectroscopy. It is deduced that the negative association energy dopants decrease the conversion of Ce+4 into Ce+3 and, hence, scavenge the oxygen vacancies, evidenced by the observed increase in the allowed direct bandgap, decrease in the integrated fluorescence intensity, and increased the size of doped nanoparticles. The opposite trends are obtained when the positive association dopants are used. It is concluded that the determining factor as to whether a lanthanide dopant in ceria acts as a generator or scavenger of oxygen vacancies in ceria nanoparticles is the sign of the association energy between the element and the oxygen vacancies. The ability to tailor the ionization state of cerium and the oxygen vacancy concentration in ceria has applications in a broad range of fields, which include catalysis, biomedicine, electronics, and environmental sensing.