Mandal Bappaditya, Mondal Aparna, Ray Sirsendu Sekhar, Kundu Amar
Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India.
Dalton Trans. 2016 Jan 28;45(4):1679-92. doi: 10.1039/c5dt03688g. Epub 2015 Dec 24.
Mesoporous Sm(3+) doped CeO2 (Ce-Sm) with a nanocrystalline framework, a high content of Ce(3+) and surface area (184 m(2) g(-1)), have been synthesized through a facile aqueous solution-based surfactant assisted route by using inorganic precursors and sodium dodecyl sulphate as a template. The XRD results indicate that the calcined Ce-Sm and even the as-prepared material have a cubic fluorite structure of CeO2 with no crystalline impurity phase. XRD studies along with HRTEM results confirmed the formation of mesoporous nanocrystalline CeO2 at a lower temperature as low as 100 °C. A detailed analysis revealed that Sm(3+) doping in CeO2 has increased the lattice volume, surface area, mesopore volume and engineered the surface defects. Higher concentrations of Ce(3+) and oxygen vacancies of Ce-Sm resulted in lowering of the band gap. It is evident from the H2-TPR results that Sm(3+) doping in CeO2 strongly modified the reduction behavior of CeO2 by shifting the bulk reduction at a much lower temperature, indicating increased oxygen mobility in the sample which enables enhanced oxygen diffusion at lower temperatures, thus promoting reducibility, i.e., the process of Ce(4+)→ Ce(3+). UV-visible transmission studies revealed improved autocatalytic performance due to easier Ce(4+)/Ce(3+) recycling in the Sm(3+) doped CeO2 nanoparticles. From the in vitro cytotoxicity of both pure CeO2 and Sm(3+) doped CeO2 calcined at 500 °C in a concentration as high as 100 μg mL(-1) (even after 120 h) on MG-63 cells, no obvious decrease in cell viability is observed, confirming their excellent biocompatibility. The presence of an increased amount of surface hydroxyl groups, mesoporosity, and surface defects have contributed towards an improved autocatalytic activity of mesoporous Ce-Sm, which appear to be a potential candidate for biomedical (antioxidant) applications.
通过使用无机前驱体和十二烷基硫酸钠作为模板，采用简便的基于水溶液的表面活性剂辅助路线，合成了具有纳米晶骨架、高含量Ce(3+)和表面积（184 m² g⁻¹）的介孔Sm(3+)掺杂CeO₂（Ce-Sm）。XRD结果表明，煅烧后的Ce-Sm以及制备的材料都具有CeO₂的立方萤石结构，无结晶杂质相。XRD研究以及HRTEM结果证实，在低至100℃的较低温度下形成了介孔纳米晶CeO₂。详细分析表明，CeO₂中Sm(3+)的掺杂增加了晶格体积、表面积、介孔体积并设计了表面缺陷。Ce-Sm中较高浓度的Ce(3+)和氧空位导致带隙降低。从H₂-TPR结果可以明显看出，CeO₂中Sm(3+)的掺杂通过在低得多的温度下移动体相还原，强烈改变了CeO₂的还原行为，表明样品中的氧迁移率增加，这使得在较低温度下氧扩散增强，从而促进了还原性，即Ce(4+)→Ce(3+)的过程。紫外可见透射研究表明，由于Sm(3+)掺杂的CeO₂纳米颗粒中Ce(4+)/Ce(3+)更容易循环，其自催化性能得到了改善。从纯CeO₂和在500℃煅烧的Sm(3+)掺杂CeO₂在高达100 μg mL⁻¹浓度下（即使在120小时后）对MG-63细胞的体外细胞毒性来看，未观察到细胞活力明显下降，证实了它们具有优异的生物相容性。表面羟基数量增加、介孔性和表面缺陷的存在有助于提高介孔Ce-Sm的自催化活性，这似乎是生物医学（抗氧化剂）应用的潜在候选材料。
