氧化铈纳米粒子的合理合成概念：粒径对储氧能力的影响,The Journal of Physical Chemistry C

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氧化铈纳米粒子的合理合成概念：粒径对储氧能力的影响
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-03-05 , DOI: 10.1021/acs.jpcc.0c00010
Elifkübra Özkan _{1,

2} , Pascal Cop _{1,

3} , Felix Benfer ₁ , Alexander Hofmann ₂ , Martin Votsmeier _{2,

4} , Juan M. Guerra _{3,

5} , Marcel Giar _{3,

5} , Christian Heiliger _{3,

5} , Herbert Over _{1,

3} , Bernd M. Smarsly _{1,

3}

Affiliation

通过合理设计合成概念，基于特殊的水热程序，制备了化学计量的二氧化铈纳米颗粒，粒径在2至12 nm之间。通过成核和生长的解耦以及合成温度和时间的适当变化来实现粒度的这种调节。与以前使用三价铈化合物的研究相比，我们使用了四价铈前体，该氧化铈粉末由低微应变和低体积缺陷浓度的单个颗粒组成，因此几乎是理想的化学计量比（CeO _2.0）在粒子的内部。由于这些特征，所获得的纳米颗粒被用作研究粒径与储氧量（OSC）之间关系的理想材料。OSC随着粒径的减小而增加，这是可以预期的，因为此参数对应于表面上的氧交换。相比之下，作为一个关键结果，我们发现所谓的完整OSC（OSCc）随着粒径的增加而增加，这是违反直觉的，因为该参数不应取决于粒子的尺寸。此外，这些粒子使用基于声子限制模型的理论计算，仅通过粒径就可以定量描述CeO ₂的F _2g模的拉曼红移。

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Rational Synthesis Concept for Cerium Oxide Nanoparticles: On the Impact of Particle Size on the Oxygen Storage Capacity

Stoichiometric cerium oxide nanoparticles with different sizes, ranging between 2 and 12 nm, were prepared by a rational design of the synthetic concept, based on a special hydrothermal procedure. This tuning in particle size was achieved by the decoupling of nucleation and growth, as well as the suitable variation of synthesis temperature and time. In contrast to previous studies utilizing a trivalent cerium compound, we used a tetravalent cerium precursor which results in a cerium oxide powder consisting of single particles with low microstrain and low concentration of bulk defects and, hence, an almost ideal stoichiometry (CeO_2.0) in the particles’ interior. Owing to these features, the obtained nanoparticles were used as an ideal material for the investigation of the relationship between the particle size and the oxygen storage capacity (OSC). The OSC increased with decreasing particle size, which is expected, as this parameter corresponds to the exchange of oxygen at the surface. By contrast, as a key result, we found that the so-called complete OSC (OSCc) increases with the particle size, which is counterintuitive, as this parameter should not be dependent on the particles’ dimension. Furthermore, these particles allowed for a quantitative description of the Raman redshift of the F_2g mode of CeO₂ in terms of solely the particle size, using theoretical calculations based on the phonon confinement model.

更新日期：2020-04-24

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