Ranasinghe Kisa S, Singh Rajnish, Leshchev Denis, Vasquez Angel, Stavitski Eli, Foster Ian
Department of Physics, Kennesaw State University, Marietta, GA 30060, USA.
Department of Chemistry and Biochemistry, Kennesaw State University, Kennesaw, GA 30144, USA.
Nanomaterials (Basel). 2022 Jul 10;12(14):2363. doi: 10.3390/nano12142363.
Mixed-valence cerium oxide nanoparticles (nanoceria) have been investigated with pronounced interest due to a wide range of biomedical and industrial applications that arises from its remarkable redox catalytic properties. However, there is no understanding of how to control the formation of these two types of nanoceria to obtain Ce/Ce ratios required in various applications. In this work, using a soluble borate glass, nanoceria with specific ratios of Ce/Ce are created and extracted via controlled glass-melting parameters. Glass embedded with nanoceria as well as nanoceria extracted from the glass were studied via XANES and fitted with the Multivariate Curve Resolution (MCR) technique to calculate the ratio of Ce/Ce. Results show that mixed-valence nanoceria with specific ratios are hermetically sealed within the glass for long durations. When the glass dissolves, the mixed-valence nanoceria are released, and the extracted nanoceria have unchanged Ce/Ce ratios. Furthermore, TEM investigation on released nanoceria show that the nanoceria consist of several different structures. Although nanocrystal structures of CeO, CeO, and CeO contribute to the reduced state, a new quasi-stable phase of CeO1.66 has been observed as well.
混合价态的氧化铈纳米颗粒（纳米氧化铈）因其显著的氧化还原催化特性所带来的广泛生物医学和工业应用而受到了广泛关注。然而，目前尚不清楚如何控制这两种类型纳米氧化铈的形成，以获得各种应用所需的Ce³⁺/Ce⁴⁺ 比率。在这项工作中，使用一种可溶性硼酸盐玻璃，通过控制玻璃熔化参数来制备并提取具有特定Ce³⁺/Ce⁴⁺ 比率的纳米氧化铈。通过X射线吸收近边结构（XANES）对嵌入纳米氧化铈的玻璃以及从玻璃中提取的纳米氧化铈进行了研究，并采用多元曲线分辨（MCR）技术进行拟合，以计算Ce³⁺/Ce⁴⁺ 比率。结果表明，具有特定比率的混合价态纳米氧化铈在玻璃中被长期密封保存。当玻璃溶解时，混合价态纳米氧化铈被释放出来，并且提取出的纳米氧化铈的Ce³⁺/Ce⁴⁺ 比率保持不变。此外，对释放出的纳米氧化铈进行的透射电子显微镜（TEM）研究表明，纳米氧化铈由几种不同的结构组成。虽然CeO₂、CeO₂ 和CeO₂ 的纳米晶体结构有助于呈现还原态，但也观察到了一种新的准稳定相CeO₁.₆₆。
