Rudra Saoni, Debnath Gouranga H, Mukherjee Prasun
Centre for Research in Nanoscience and Nanotechnology, University of Calcutta JD-2, Sector-III, Salt Lake Kolkata-700106 West Bengal India
RSC Adv. 2018 May 16;8(32):18093-18108. doi: 10.1039/c8ra02403k. eCollection 2018 May 14.
This work reports the photophysical properties of 1-thioglycerol capped hydrophilic terbium cation incorporated (doped) zinc sulfide [Zn(Tb)S] nanoparticles, which have been post-synthetically modified using Pb [Zn(Tb)S/Pb] under ambient conditions with [Zn(Tb)S] : [Pb] = 1 : 10-1 : 10, essentially providing a scenario with low to heavy co-doping and ultimately the possibility of forming a material of different chemical identity. The effects of selected concentrations of [Zn(Tb)S] : [M ] = 1 : 1 and 1 : 10 have also been evaluated for the post-synthetic addition of Hg, Cd, Ca, Mg, Na and K. The broad zinc sulfide nanoparticle and sharp Tb emission have different dependence on the relative reactant concentration, with cation identity playing a significant role. The underlying photophysical processes have been rationalized based on the interplay among the (i) cation exchange, (ii) modification of the structural properties of the nanoparticles without necessarily exchanging the cations and (iii) emission enhancement of terbium dopants. In cases where Tb emission is apparent, all the nanoparticles studied demonstrate an optical antenna effect, thus accessing a lower Tb concentration regime compared to in bulk environments. The results presented provide an avenue for the detection of heavy metal ions in general and Pb in particular, with a limit of detection that is at least in the range of sub-ppm, using either the broad ZnS or sharp Tb emission, respectively. This strategy provides an avenue to combine (i) the extremely sensitive and easily accessible analytical technique of photoluminescence spectroscopy, (ii) post-synthetic modification reactions in semiconductor nanoparticles that can be performed with less experimental demand, (iii) time-gated measurement related to the longer luminescence lifetime of terbium cations and (iv) the simultaneous use of broad ZnS nanoparticle and sharp Tb emission from the same assembly, helping eliminate false positive results.
这项工作报道了1-硫代甘油包覆的、掺入（掺杂）亲水性铽阳离子的硫化锌[Zn(Tb)S]纳米颗粒的光物理性质，这些纳米颗粒在环境条件下使用铅进行了后合成修饰[Zn(Tb)S/Pb]，[Zn(Tb)S] : [Pb] = 1 : 10 - 1 : 10，基本上提供了一种从低共掺杂到重共掺杂的情况，并最终有可能形成具有不同化学特性的材料。对于Hg、Cd、Ca、Mg、Na和K的后合成添加，还评估了[Zn(Tb)S] : [M ] = 1 : 1和1 : 10的选定浓度的影响。宽泛的硫化锌纳米颗粒发射和尖锐的铽发射对相对反应物浓度有不同的依赖性，阳离子特性起着重要作用。基于以下相互作用对潜在的光物理过程进行了合理化解释：(i)阳离子交换；(ii)在不一定交换阳离子的情况下对纳米颗粒结构性质的修饰；(iii)铽掺杂剂的发射增强。在铽发射明显的情况下，所有研究的纳米颗粒都表现出光学天线效应，因此与本体环境相比，可进入更低的铽浓度范围。所呈现的结果为一般重金属离子的检测，特别是铅的检测提供了一条途径，使用宽泛的ZnS发射或尖锐的铽发射，检测限至少在亚ppm范围内。该策略提供了一条途径来结合：(i)极其灵敏且易于使用的光致发光光谱分析技术；(ii)半导体纳米颗粒中的后合成修饰反应，其可以在较少实验要求下进行；(iii)与铽阳离子较长发光寿命相关的时间分辨测量；(iv)同时使用来自同一组件的宽泛的ZnS纳米颗粒发射和尖锐的铽发射，有助于消除假阳性结果。
