MPTES包覆下转换纳米粒子NaYF4:Yb^3+及其氧化改性

Down-conversion nanoparticles NaYF4:Yb^3+coated with MPTES and its oxidation modification

为了提高下转换纳米粒子NaYF4:Yb3+对蛋白质类纤维的结合力,本文采用γ-巯丙基三乙氧基硅烷(MPTES)对其进行水解包覆并利用醋酸-过氧化氢氧化改性。利用TEM、FTIR和XPS分析各阶段反应产物形貌和组成,并利用XRD和PL光谱表征了样品的物相结构和红外发射性能。实验结果表明:随着MPTES量的增加,纳米粒子NaYF4:Yb3+表面形成的包覆层厚度也增大,当MPTES体积达到1.5mL时,包覆层厚度增加不再明显;产物FTIR谱图表明纳米粒子表面形成了巯基化二氧化硅包覆层,并由醋酸-过氧化氢将SH原位氧化成SO3基团;XPS硫元素精细谱证实氧化后的产物只有高价态(+4)且未见低价态(-2)的硫元素。最后,XRD和PL发射光谱结果表明:包覆和氧化改性并未对纳米粒子NaYF4:Yb3+晶型产生影响,包覆改性后的产物下转换发射强度明显提高。

For improving the adhesion of down-conversion nanoparticles NaYF4:Yb3+to protein fibers,the nanoparticles were coated via the hydrolysis of gamma-mercaptopropyl triethoxysilane,then the products were oxidized by acetic acid-hydrogen peroxide.The morphology and composition of reactions products of the various steps were analyzed by transmission electron microscopy(TEM),Fourier transform infrared(FTIR)and X-ray photoelectron spectroscopy(XPS).X-ray diffraction(XRD)and photoluminescence(PL)were used to characterise the phase structure and infrared emission performance of samples,respectively.The result revealed that the layer on the surface of nanoparticles NaYF4:Yb3+was thickening with the increase of MPTES.When the volume of MPTES reached 1.5mL,the thickening of the coating was not obvious.The FTIR spectra of the products showed that the surface of the nanoparticles formed a thioglylated silica layer,and the thiohydro group was oxidized in situ to sulfonic group by acetic acid-hydrogen peroxide.The XPS spectrum confirmed that the oxidized products had only high-valence(+4)and no low-valence(-2)sulfur element.Finally,the spectra of XRD and PL indicated that the coating and oxidation modification had no effect on the crystalline phases of nanoparticles NaYF4:Yb^3+.The down-conversion emission strength of the coated product increased significantly due to the reduction of surface defects.