Abstract Novel PEI-modified NaBiF4:Yb3+/Er3+ upconversion nanoparticles (UCNPs) with hollow structure were prepared by a surface modification free one-step solvothermal method and applied as a luminescent probe to determinate water content in organic solvents. XRD, SEM and HRTEM results demonstrate that the obtained PEI-NaBiF4:Yb3+/Er3+ UCNPs are pure hexagonal phase with uniform size. The successful modification of PEI on the UCNPs surface was evidenced by ζ-potential test, XPS and TG analysis. These synthesized UCNPs are disintegrated into smaller nanoparticles in the presence of water and thus result in a surface quenching effect, which show the features of 0–100% wide range water response in various organic solvents. The sensing performance towards real samples was validated by the water content determination in beer, rum and white spirit. Furthermore, the luminescence intensity variation of the PEI-modified NaBiF4:Yb3+/Er3+ enable the test visualization and ease of portability.

中文翻译：

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一步合成用于水响应发光探针的中空 PEI-NaBiF4:Yb3+/Er3+ 上转换纳米粒子

摘要 采用无表面修饰的一步溶剂热法制备了新型PEI修饰的NaBiF4:Yb3+/Er3+上转换纳米粒子(UCNPs)，并将其作为发光探针用于测定有机溶剂中的水分含量。XRD、SEM 和 HRTEM 结果表明得到的 PEI-NaBiF4:Yb3+/Er3+ UCNPs 是纯六方相，尺寸均匀。通过 ζ 电位测试、XPS 和 TG 分析证明了 UCNPs 表面上 PEI 的成功修饰。这些合成的 UCNP 在水存在下分解成更小的纳米粒子，从而产生表面淬灭效应，在各种有机溶剂中表现出 0-100% 宽范围水响应的特征。通过啤酒、朗姆酒和白酒中的含水量测定验证了对真实样品的传感性能。