物理化学学报 >> 2020, Vol. 36 >> Issue (7): 1907011.doi: 10.3866/PKU.WHXB201907011

所属专题: 纳米复合材料

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上转换纳米粒子的Y(OH)CO3壳层包覆及壳层转化

刘冬梅,陈秀梅,袁泽,闾敏,殷丽莎*(),谢小吉*(),黄岭   

  • 收稿日期:2019-07-01 录用日期:2019-07-26 发布日期:2020-03-21
  • 通讯作者: 殷丽莎,谢小吉 E-mail:iamlsyin@njtech.edu.cn;iamxjxie@njtech.edu.cn
  • 基金资助:
    国家重点研发计划(2017YFB1002900);江苏省自然科学基金(BK20160987)

Coating and Transforming the Y(OH)CO3 Shell on Upconversion Nanoparticles

Dongmei Liu,Xiumei Chen,Ze Yuan,Min Lu,Lisha Yin*(),Xiaoji Xie*(),Ling Huang   

  • Received:2019-07-01 Accepted:2019-07-26 Published:2020-03-21
  • Contact: Lisha Yin,Xiaoji Xie E-mail:iamlsyin@njtech.edu.cn;iamxjxie@njtech.edu.cn
  • Supported by:
    the National Key Research and Development Program of China(2017YFB1002900);the Natural Science Foundation of Jiangsu Province, China(BK20160987)

摘要:

制备如异质核-壳结构等不同结构的镧系离子掺杂的上转换纳米材料对上转换纳米材料的基本性质研究及应用至关重要。在本工作中,我们采用简单的共沉淀方法在NaGdF4:Yb/Tm上转换纳米粒子表面包覆了无定形的Y(OH)CO3壳层。通过透射电子显微镜,X射线衍射,能量色散X射线荧光光谱等物理表征手段研究了所得纳米粒子的结构和形貌,结果表明Y(OH)CO3壳层可以在300 ℃附近转化形成YOF,形成异质核-壳结构。同时,初步研究结果显示该方法也可拓展用于其他无定形壳层的包覆及蛋黄-蛋壳结构纳米粒子的制备。这些结果表明这种方法在制备不同结构的上转换纳米材料方面有良好的应用前景。

关键词: 镧系元素, 掺杂, 发光, 核-壳结构, 纳米材料

Abstract:

Along with the promising applications of lanthanide doped upconversion nanomaterials in diverse fields such as biology, anti-counterfeiting, and lasering, the demand for multifunctional upconversion nanomaterials is increasing. One effective means of obtaining these nanomaterials is to fabricate upconversion nanomaterial-based heterostructures, which may provide superior properties as compared to the sum of the parts. However, obtaining heterostructured upconversion nanomaterials remains challenging mainly because of the crystal lattice mismatch between upconversion nanomaterials and other materials. Typically used strategies for synthesizing upconversion nanomaterial-based heterostructures are applicable only to limited types of materials. Alternatively, transformation of the intermediate layer is a promising strategy used to obtain these heterostructures. Nevertheless, this method remains in its infancy and, to date, only a few intermediate layers have been developed. New types of intermediate layers are therefore highly desirable. In this study, we show that amorphous Y(OH)CO3 can be a promising candidate as an intermediate layer for fabricating upconversion nanoparticle-based heterostructures. As a proof-of-concept experiment, ligand-free NaGdF4:Yb/Tm upconversion nanoparticles were first prepared as core nanoparticles. The Y(OH)CO3 shell was then directly coated on the NaGdF4:Yb/Tm upconversion nanoparticles in an aqueous solution using urea and Y(NO3)3, by a homogeneous precipitation approach. The thickness of the resulting Y(OH)CO3 shell could be tuned by adjusting the amounts of either urea or Y(NO3)3. The as-coated Y(OH)CO3 shell could be easily converted to YOF by heating at 300 ℃, yielding NaGdF4:Yb/Tm@YOF core-shell heterostructured nanoparticles. In addition, we found that the NaGdF4 core could be transformed to lanthanide oxide fluoride if the NaGdF4:Yb/Tm@Y(OH)CO3 core-shell nanoparticles were heated at 350 ℃. We also observed that treating the NaGdF4:Yb/Tm@Y(OH)CO3 core-shell nanoparticles at even higher temperatures (e.g., 400 ℃) produced aggregations of nanoparticles without regular morphologies. The transformation of the shell can be attributed to the decomposition of Y(OH)CO3 and reactions between the Y(OH)CO3 shell and NaGdF4 core. Meanwhile, the transformation of the NaGdF4 core at relatively high temperatures could be primarily due to the reactions between Y(OH)CO3 and NaGdF4. Notably, in this study, the core-shell structured nanoparticles, with either a Y(OH)CO3 or YOF shell, maintained the photon upconversion properties of NaGdF4:Yb/Tm upconversion nanoparticles. In addition, the method used here could be extended to the coating of other shells such as Tb(OH)CO3 and Yb(OH)CO3 on upconversion nanoparticles. Moreover, the NaGdF4:Yb/Tm@Y(OH)CO3 core-shell nanoparticles could be transformed to other nanoparticles with novel structures such as yolk-shell nanoparticles. These results can pave the way for preparing upconversion nanoparticle-based heterostructures and multifunctional composites, thus promoting new applications of upconversion nanoparticles.

Key words: Lanthanide, Doping, Luminescence, Core-shell, Nanomaterials

MSC2000: 

  • O648