基于稀土掺杂上转换纳米材料NaYF_(4):Yb,Er@TGA直接对金属离子进行定量分析的方法探究

目的:基于荧光猝灭或增强机制,构建稀土掺杂上转换纳米材料NaYF_(4):Yb,Er@TGA直接对金属离子进行定量分析的方法,实现对金属离子快速、准确、灵敏检测。方法:通过溶剂热法制备出性能优良的稀土掺杂上转换纳米材料NaYF_(4):Yb,Er@TGA,并对其进行表征;通过测量14种常见的金属离子对NaYF_(4):Yb,Er@TGA荧光强度的影响,筛选能够引起NaYF_(4):Yb,Er@TGA荧光强度增强或下降,且与金属离子浓度呈线性关系的金属离子类型,进而建立检测新方法。结果:金属离子Mg^(2+)、Fe^(3+)分别在浓度范围为0~7.00μg/mL、0~6.00μg/mL与NaYF_(4):Yb,Er@TGA的荧光强度呈现良好的线性关系,其标准曲线方程的线性系数分别为0.9924、0.9982,检出限分别为1.79μg/mL、1.30μg/mL,加标回收率分别为95.5%~98.8%、92.5%~97.8%,方法相对标准偏差分别为4.05%、8.18%。结论:该方法检测限低、准确度较高、精密度较好,有望用于实际样品中Mg^(2+)、Fe^(3+)定量分析。

Tm^(3+)高掺杂的NaYF_(4)纳米颗粒制备与发光性能研究

为了研究Tm^(3+)高掺杂浓度下NaYF_(4)纳米颗粒的上转换发光性能,采用热分解法合成了六方相的NaYF_(4)∶Yb^(3+)/Tm^(3+)(20%/8%)纳米颗粒,并用X射线衍射对其结构进行了表征,用透射电子显微镜对其形貌和大小进行了表征.通过搭建上转换光谱测试系统,研究了在980 nm激光激发下NaYF_(4)∶Yb^(3+)/Tm^(3+)纳米颗粒的上转换发光光谱,并分析了其发光机制.通过计算475,513,650,744,805 nm处发光强度与激发光功率间的依赖关系,证明了其上转换发光过程为双光子过程.

双波长泵浦含有Er^(3+)∶NaYF_(4)纳米晶氟氧化物微晶玻璃的上转换发光性能

高效的光调制能够显著提高光转换效率和调节光响应速率,在光电子学领域中表现出巨大的应用潜力。然而,光子之间的弱相互作用对操纵光子‐光子相互作用造成了巨大的障碍。本文采用850 nm和1550 nm激光同时激发含有Er^(3+)∶NaYF_(4)纳米晶体的氧氟化物微晶玻璃,可以实现绿色上转换荧光的快‐慢光调制。与两束单波长激发的发光强度之和相比,双波长同时激发的绿色上转换发光强度明显提高了一个数量级。值得注意的是,绿色上转换发光快‐慢响应速率依赖于双波长激发的泵浦策略,显示出高达4倍的快‐慢响应差异。研究表明,双波长激发绿色上转换发光的快‐慢光调制在新型的全光开关中具有广阔的应用前景。

NaYF_(4)∶Yb,Er纳米粒子的合成及免疫传感器的制备与应用

稀土掺杂发光纳米材料具有独特的性质,如发射寿命长、发射波段窄、Stokes位移大、光稳定性强、荧光寿命长、反自发荧光能力强等特点,为进一步探索稀土纳米粒子在生物传感器方面的应用,首先研究上转换稀土纳米粒子的可控合成,后采用巯基乙酸(TGA)对其表面进行改性,再将其固癌胚抗原制备免疫传感器,进行了电化学发光测试和样品检测。结果表明:溶剂法合成的纳米粒子形貌均一,分散性好,构建的免疫传感器的检测极限低达3.2pg/mL。

Simultaneous Morphologies and Luminescence Control of NaYF_(4)∶Yb/Er Nanophosphors by Surfactants for Cancer Cell Imaging

Hydrophilic rare-earth up-conversion nanophosphors(UCNPs)with small sizes and a strong up-conversion luminescence have attracted much interest.Herein the simultaneous control of morphologies and the up-conversion luminescence intensities was reported for NaYF_(4)∶Yb/Er nanophosphors by a facile hydrothermal procedure with different surfactants.With the change of the surfactants from polyvinylpyrrolidone(PVP)to sodium citrate(CIT),edetate disodium(EDTA)or sodium dodecyl benzenesulfonate(SDBS),the morphology of NaYF_(4)∶Yb/Er nanophosphors transformed from nanoparticles with a diameter of about 70.0 nm to hexagonal nanoblocks with a thickness of about 125.0 nm and a length of about 240.0 nm,nanorods with a diameter of about 700.0 nm and a length of about 2.6μm,or nanowires with a diameter of 250.0 nm and a length of about 3.2μm.Simultaneously,their up-conversion luminescence intensity went down gradually under laser irradiation at a wavelength of 980 nm due to the increase of photobleaching.PVP-capped NaYF_(4)∶Yb/Er nanoparticles exhibited the smallest size and the strongest up-conversion luminescence intensity.Biological experiment results revealed that NaYF_(4)∶Yb/Er nanophosphors exhibited a high biocompatibility and could be used as biological labels with a perfect signal-to-noise ratio for cancer cell imaging.

NaYF_(4)掺杂Yb^(3+),Ho^(3+)的低温上转换荧光特性研究

目的确定β-NaYF_(4)掺杂Ho^(3+)和Yb^(3+)离子的微米晶体在低温下的上转换荧光特性。方法通过水热法合成β-NaYF_(4)微米晶体,用FLS980光谱仪获取样品在室温和4~294 K温度下的荧光光谱以及荧光寿命,应用玻尔兹曼分布原理对测试结果进行分析。结果确定了最佳的稀土离子掺杂浓度。通过对荧光强度和荧光寿命的分析,结合玻尔兹曼分布得出温度在上转换发光中的作用。结论随着温度的升高,Ho^(3+)的^(5)F_(5)→^(5)I_(8)和^(5)S_(2)/^(5)F_(4)→^(5)I_(8)跃迁发射峰逐渐减弱。

TiO_(2)空心微球在NaYF_(4)∶Yb^(3+),Er^(3+)/商业TiO_(2)染料敏化太阳能电池中的应用

以TiCl_(3)为钛源,水热法制备高散射性能的锐钛矿TiO_(2)空心微球。以商业TiO_(2)(P25)/NaYF_(4)∶Yb~(^(3+)),Er^(3+)混合材料为底层薄膜,TiO_(2)空心微球为反射层组成双层结构光阳极薄膜,优化了太阳能电池性能。结果表明:新型结构的太阳能电池短路光电流(J_(sc)=16.81mA/cm^(2))、开路光电压(V_(oc)=0.78V)、填充因子(FF=0.66)和光电转化效率(η=8.65%),其光电转化效率与纯P25(6.70%)光阳极和P25/NaYF_(4)∶Yb^(3+),Er^(3+)(7.35%)光阳极相比较分别提升了29%和18%。

793 nm光激发下NaYF_(4):Eu^(3+)上转换发光性能

利用水热法制备NaYF_(4):Eu^(3+)的上转换发光材料,用荧光光谱、CIE色坐标和X射线粉末衍射表征样品的发光性质,探索影响上转换发光性能的要素:Eu^(3+)的掺杂量,pH值,EDTA-2Na:Eu^(3+)的摩尔比及Y^(3+):F^(-)的摩尔比。结果表明:在793 nm激发下,Eu^(3+)的掺杂量为14%,pH值为6,EDTA-2Na:Eu^(3+)的摩尔比为3:1及Y^(3+):F^(-)的摩尔比为1:7时,NaYF_(4):Eu^(3+)的上转换发光性能最好。

微波法快速可控合成红光发射的NaYF_(4):Yb^(3+)/Er^(3+)上转换纳米材料

采用单模微波法快速合成了红光发射的NaYF_(4):Yb^(3+)/Er^(3+)上转换纳米材料,探讨了反应温度、反应时间、反应溶剂以及掺杂离子浓度对目标产物合成的影响,并通过TEM,XRD和荧光光谱对所得样品的形貌、结构及发光性能进行了表征。结果表明,该方法能高效制备平均粒径为50 nm、具有立方相结构的NaYF_(4):Yb^(3+)/Er^(3+)上转换纳米材料,其在980 nm激光激发下,当Yb^(3+)和Er^(3+)掺杂浓度为20%和2%时,呈现强红光发射。通过创新发光材料的合成方法实现了强红光发射上转换纳米材料在10 min内的简单快速合成,显著提高了材料的合成效率。该研究合成的纳米材料在生物标记、细胞成像、生物检测等领域也具有巨大的应用前景。

Yb^(3+)/Er^(3+)双掺杂的NaYF_(4)上转换纳米功能材料的制备与设计优化

为合成单分散、形貌尺寸均一、高上转换发光的稀土上转换纳米功能材料,本文以稀土氯化物为反应前驱体,采用溶剂热法合成Yb^(3+)/Er^(3+)双掺杂的NaYF_(4)上转换发光纳米材料,并对稀土元素掺杂比例、反应时间、反应温度、油酸体积分数等影响材料结构、形貌和发光性能的条件进行了优化。结果表明,最佳稀土元素掺杂比例为78%Y^(3+)∶20%Yb^(3+)∶2%Er^(3+),反应时间90 min,反应温度300℃,油酸体积分数15.5%。在最佳条件下,本研究合成的NaYF_(4)∶Yb^(3+),Er^(3+)纳米材料形貌呈六方晶型,直径约为30 nm,与标准卡片匹配良好;在980 nm近红外光激发下,该纳米材料在529 nm、542 nm以及657 nm处均可以观察到Er^(3+)的特征发射峰,且发射出明亮的绿色荧光。本研究为后续制备修饰有不同功能基团的NaYF_(4)∶Yb^(3+),Er^(3+)纳米材料及其应用奠定了基础。

NaYF_(4):Yb,Er@SiO_(2)的高温相变及上转换发光性能研究

通过固-液热分解法合成平均尺寸为27 nm的六方相NaYF_(4):Yb,Er上转换纳米晶。制备了NaYF_(4):Yb,Er@SiO_(2)核壳纳米粒子,壳层厚度约为8 nm。将NaYF_(4):Yb,Er@SiO_(2)分别在不同高温下焙烧3 h,发现600℃下产物物相未发生变化,但向非晶态过渡;700、800℃下NaYF4内核与SiO_(2)壳层发生化学反应,产物物相均转变为NaYSiO_(4)。样品均用980 nm红外激光进行激发,显示出强烈的可见光上转换发射。以初始NaYF_(4):Yb,Er@SiO_(2)的上转换发光强度为对比样,随着焙烧温度的升高,样品的发光强度依次提高。这与理论上低声子能量的氟化物发光强度更高不符,可能原因是高温处理后样品去除了部分晶格缺陷和有机杂质。

六角柱形NaErF_(4)和NaErF_(4)@NaYF_(4)核壳微粒制备及多色上转换荧光调控性能

采用简单的水热法合成了六角柱形NaErF_(4)和NaErF_(4)@NaYF_(4)核壳上转换发光材料,利用扫描电镜(SEM)、X射线粉末衍射(XRD)和荧光光谱(PL)等表征对材料的形貌、结构和上转换发光性能进行了研究。结果表明,纯NaErF_(4)样品为六角柱形,边长和厚度均为1μm左右,样品表面光滑。随着NaYF_(4)壳层的包覆,六角相NaErF_(4)周围出现了大量的立方相NaYF_(4)纳米颗粒,得到了NaErF_(4)@NaYF_(4)核壳结构。荧光光谱表明,通过在六角柱形NaErF_(4)表面包覆NaYF_(4)壳层,可以有效增强上转换发光强度,其中,位于527,543,663 nm处的3个发射峰分别对应于Er^(3+)的^(2)H_(11/2)→^(4)I_(15/2)、^(4)S_(3/2)→^(4)I_(15/2)和^(4)F_(9/2)→^(4)I1_(5/2)能级跃迁。随着壳层中Y∶F比例的增加,立方相NaYF_(4)的晶体衍射峰逐渐增强;同时,对应的NaErF_(4)@NaYF_(4)样品发射光谱中红绿比(R/G)逐渐增大,发光颜色也从绿色、经黄绿色逐渐向黄色过渡,实现了多色发光。

纤维状中空结构NaYF_(4):Yb^(3+),Er^(3+)上转换材料的合成及防伪应用

采用水溶性聚合物聚乙烯亚胺(PEI)调介下的水热法,一步合成了具有纤维状中空结构的六方相NaYF4:Yb^(3+),Er^(3+)上转换荧光材料,并将其作为荧光填料,通过流延成膜法制备了具有上转换荧光性能的壳聚糖/聚乙烯醇(CS/PVA)荧光复合薄膜。探究了PEI配体含量和反应体系pH值对合成的上转换材料的形貌、晶型和荧光性能的影响,以及壳聚糖/聚乙烯醇荧光复合薄膜中荧光填料的最佳掺杂量。研究结果表明,在PEI含量为0.3 g且反应体系pH=5的条件下,合成的产物为具有纤维状中空结构的六方相NaYF4:Yb^(3+),Er^(3+)。荧光光谱表明,合成的NaYF4:Yb^(3+),Er^(3+)上转换材料在980 nm激光激发下具有优异的荧光性能。当荧光填料的掺杂质量分数为3.0%时,制备的NaYF4:Yb^(3+),Er^(3+)/(CS/PVA)荧光复合薄膜具有最佳的透明度和上转换荧光特性。

β-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4)复合水凝胶材料的制备及其应用

为了有效解决日益严重的水污染问题,本文研究了β-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4)复合材料的制备及其在可见光下催化降解亚甲基蓝模拟废水的最佳工艺条件。首先,利用溶剂热法合成了β-NaYF_(4):Yb^(3+),Tm^(3+),再将煅烧法制备的g-C_(3)N_(4)加入聚丙烯酸/聚乙烯醇水溶液,后滴入饱和硼酸溶液获得β-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4)/聚丙烯酸/聚乙烯醇复合水凝胶。利用X射线衍射仪、场发射扫描电子显微镜、紫外-可见分光光度计、热重分析仪、全自动比表面积微孔孔隙分析仪等进行表征;利用正交试验L_(16)(4^(5))考察复合材料的投加量、复合材料的比例、温度、亚甲基蓝溶液的pH、光照时间等因素,探索降解亚甲基蓝的最佳工艺条件。正交试验结果表明:光照时间为20.0h、pH为7.00、复合材料的投加量0.25g、温度20.0℃、复合材料活性组分β-NaYF_(4):Yb^(3+),Tm^(3+)与g-C_(3)N_(4)的比例为1∶4,此时对30.0mg/L亚甲基蓝降解率达到94.84%,循环降解亚甲基蓝模拟废水4次后的降解率仍高达为86.22%。

稀土上转换光催化剂的研究进展

稀土具有的上转换(UC)发光性能为光催化剂的发展拓宽了方向。基于稀土元素掺杂改性和稀土上转换剂复合两种功能均能体现稀土上转换性能在光催化领域的研究和应用价值,论文从以上两个方面综述稀土上转换光催化剂的研究进展。具有上转换性能的稀土元素主要有Er、Yb、Tm、Ho、Tb等,其中Yb常作为敏化剂,Er因其高效、绿色的发光性能而研究应用最为广泛。根据基质组分不同,稀土上转换剂可分为稀土氟化物、稀土卤氧化物、稀土氧化物或复合氧化物三类,其中以NaYF_(4)等的研究较为突出。UC材料研究拓宽了光催化剂在紫外-可见-红外的全光谱响应,但由于其量子效率相对较低,UC材料的构建及研究仍需要进一步深入,本文旨在为相关人员在该领域的研究提供启发和帮助。

Research Article Acetic acid-mediated rapid cubic-to-hexagonal(α-β)phase transformation for ultra-bright lanthanide-dopedβ-NaYF_(4)nanobioprobes

Hexagonal-phase NaYF_(4)(β-NaYF_(4))has been acknowledged to be one of the most efficient doping hosts to prepare bright lanthanide-doped luminescent nano-bioprobes for various biomedical applications.However,to date,it remains a great challenge to synthesize ultra-bright lanthanide-dopedβ-NaYF_(4)nano-bioprobes under a low reaction temperature by using conventional synthetic methods.Herein,we first develop an acetic acid(HAc)-mediated coprecipitation method for the preparation of ultrabright lanthanide-dopedβ-NaYF_(4)nanoprobes under a low reaction temperature at 200℃.Based on a series of comparative spectroscopic investigations,we show that the use of HAc in the reaction environment can not only promote the rapidα-βphase transformation of NaYF_(4)host at 200℃ within 1 h but also boost the absolute photoluminescence quantum yield(PLQY)of NaYF_(4)nanocrystals to 30.68%for near-infrared emission and to 3.79%for upconversion luminescence,both of which are amongst the highest values for diverse lanthanide-doped luminescent nanocrystals ever reported.By virtue of their superior nearinfrared luminescence,we achieve optical-guided dynamic vasculature imaging in vivo of the whole body at a high spatial resolution(23.8μm)under 980 nm excitation,indicating its potential for the diagnosis and treatment evaluation of vasculaturerelated diseases.

A sandwiched luminescent heterostructure based on lanthanide-doped Gd_(2)O_(2)S@NaYF_(4)core/shell nanocrystals

Lanthanide(Ln^(3+))oxysulfide nanocrystals(NCs)have great prospect in many advanced technologies;however,they suffer from a low photoluminescence efficiency due to the volatility of sulfur and deleterious surface quenching effect.Herein,we report a novel sandwiched luminescent heterostructure based on Ln^(3+)-doped Gd_(2)O_(2)S@NaYF_(4)core/shell NCs with tunable sulfur content in the sandwich layer.By means of Eu^(3+)as the sensitive structural probes,we unravel the ligand-mediated structure control of the NCs from Gd_(2)O_(3):Ln^(3+)@NaYF_(4)to Gd_(2)O_(2)S:Ln^(3+)@NaYF_(4)with tailored S2–deficiency.Such a sandwich-type core/shell heterostructure enables us to achieve efficient and multicolor downshifting and upconversion luminescence(UCL),with up to 208.8 folds of enhancement in UCL intensity as compared to that of their core-only counterparts.These findings provide a general approach for the controlled synthesis of lanthanide oxysulfide@fluoride heterostructure,which offers a new way for the materials design towards diverse emerging applications.

Mo^(6+)掺杂NaYF_(4):Yb^(3+),Ho^(3+)纳米颗粒的上转换性能研究

采用热分解法制备了不同摩尔比的Mo^(6+)-NaYF_(4):Yb^(3+),Ho^(3+)上转换纳米颗粒(UCNPs),并用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、场发射扫描电子显微镜(FE-SEM)与荧光分光光度计(FS)等对样品的性能进行表征,以探究Mo^(6+)掺杂对NaYF_(4):Yb^(3+),Ho^(3+)的发光效率、结构和形貌的影响。结果表明,制得的UCNPs为β相NaYF_(4),其分散性良好,粒径分布均匀;MoO_(3)浓度≥12.5%(摩尔分数)时,UCNPs结构已非纯β-NaYF_(4);在980 nm激光仪照射下,UCNPs发射出两束可见光(542 nm的绿光与649 nm的红光)以及一束750 nm的近红外光;钼源为MoO_(3)或(NH_(4))_(6)Mo_(7)O_(24)·4H_(2)O,Mo^(6+)的最佳掺杂浓度均为2.5%,较未掺杂Mo^(6+)的样品,绿光强度分别增大了11倍与15倍,红光强度分别增大了7.2倍与3.4倍;UCNPs的红、绿光发光均为双光子过程,Mo^(6+)掺杂并未影响NaYF_(4):Yb^(3+),Ho^(3+)纳米颗粒的上转换(UC)发光机制。

Dopant-Controlled Synthesis of Water-Soluble Hexagonal NaYF_(4) Nanorods with Efficient Upconversion Fluorescence for Multicolor Bioimaging

A novel strategy is proposed to directly synthesize water-soluble hexagonal NaYF4 nanorods by doping rare-earth ions with large ionic radius (such as La^(3+), Ce^(3+), Pr^(3+), Nd^(3+), Sm^(3+), Eu^(3+), and Gd^(3+)), and the dopant- controlled growth mechanism is studied. Based on the doping effect, we fabricated water-soluble hexagonal NaYF4:(Yb,Er)/La and NaYF4:(Yb,Er)/Ce nanorods, which exhibited much brighter upconversion fluorescence than the corresponding cubic forms. The sizes of the nanorods can be adjusted over a broad range by changing the dopant concentration and reaction time. Furthermore, we successfully demonstrated a novel depth-sensitive multicolor bioimaging for in vivo use by employing the as-synthesized NaYF4:(Yb,Er)/La nanorods as probes.

Strong interface contact between NaYF_(4):Yb,Er and CdS promoting photocatalytic hydrogen evolution of NaYF_(4):Yb,Er/CdS composites

To acquire efficient photocatalysts,it is necessary to make effective use of visible light/Near Infrared(NIR)light,which takes up a large percentage of sunlight.Integrating upconversion materials with visible light active photocatalysts has attracted much attention in this regard.The interface contact between upcon-version material and photocatalyst has potential influence on the properties and thus the performance of the system.In this work,NaYF_(4):Yb,Er/CdS composites of the upconversion material NaYF_(4):Yb,Er nanorods and CdS nanoparticles were synthesized by ion adsorption/precipitation process and were then annealed in an argon atmosphere at different temperatures to modulate the microstructures.The annealing pro-cess endows the crystal transformation of cubic CdS with low crystallinity to hexagonal CdS with high crystallinity and,importantly,good interface contact between NaYF_(4):Yb,Er and CdS.Consequently,the hy-drogen evolution activity greatly increases from 171 to 2539μmol h^(−1) g^(−1) under the light irradiation ofλ>400 nm,and from 0 to 19μmol h^(−1) g^(−1) under the light irradiation ofλ>600 nm.This work might provide a useful reference for the rational design of promising photocatalyst involving upconversion ma-terials.