This paper reports a simple, rapid and sensitive fluorescence sensor for the parallel determination of iron (III) (Fe 3+ ), terbium (III) (Tb 3+ ) and europium (III) (Eu 3+ ) ions using Carbon Dot (CD) serving as a fluorescence probe. The Carbon Dot (CD), which was synthesized via an acid-cutting method using anthracite coal as the carbon source, was found to have rich carboxyl and hydroxyl groups on its surface. The fluorescence of the as-prepared CD can be selectively quenched by the Fe 3+ ion via non-radiative electron-transfer, and furthermore, the as-prepared CD can also sensitize the luminescence of both Tb 3+ and Eu 3+ ions through the antenna effect and enhance the fluorescence of Tb 3+ and Eu 3+ by more than several orders of magnitude. Therefore, the as-prepared CD was applied as a fluorescence probe towards the parallel determination of Fe 3+ , Tb 3+ and Eu 3+ and exhibited detection limits in 0.019, 0.10 and 0.79 μM, respectively. The fluorescence quenching mechanism and energy transfer mechanism were also studied in details.
Artem Yakovliev,Tymish Y. Ohulchanskyy,Roman Ziniuk,Tereza Dias,Xin Wang,Hao Xu,Guanying Chen,Junle Qu,Anderson S. L. Gomes
In this work, the application of near infrared (NIR)-emitting NaYbF 4 :1%Tm 3+ @NaLuF 4 :30%Nd 3+ core–shell nanoparticles is reported for noninvasive probing and monitoring the temperature during photopolymerization of dental materials. When excited at 808 nm, the synthesized nanoparticles emit NIR photoluminescence (PL) with two distinctive peaks at 865 and 980 nm which correspond to radiative transitions from the doped Nd 3+ and Yb 3+ ions, respectively. Luminescence intensity ratio between these two bands is found to vary with temperature due to temperature-dependent electronic excitation energy transfer between Nd 3+ and Yb 3+ ions at the core/shell interface. This finding allows luminescence ratiometric evaluation of the in situ temperature during photopolymerization of resin cement (doped with nanoparticles) in a veneer placement procedure. In addition, the NIR emission also enables PL imaging of the distribution of the adhesive under the veneer. The results highlight that rare-earth ions–doped nanoparticles with both excitation and emission in the NIR spectral range are advantageous for both PL-based nanothermometry and imaging due to the reduced attenuation of NIR light by dental ceramics.
La 3+ - or Yb 3+ -doped TiO 2 supported on the surface of reduced graphene oxide were fabricated by adsorbed-layer nanoreactor synthesis (ANS) coupling with a solvothermal treatment to extend photocatalysis application in the advanced treatment of simulated wastewater with high salt concentration. Results showed that La 3+ or Yb 3+ could distribute in the TiO 2 lattice, only in ANS preparation with graphene oxide as the carrier, to replace Ti 4+ during the solvothermal treatment, thus introducing TiO 2 mixed-crystal and heterojunction structures in the catalysts. La 3+ or Yb 3+ caused lattice distortion structures and anionic vacancies in the TiO 2 lattice. The anionic vacancies (oxygen vacancies) might generate Ti 3+ in catalysts, thus enhancing visible-light response, due to impurity levels introduced by La 3+ or Yb 3+ . As the strong adsorption capability of the catalyst for phenol was not interfered by salt ions in the simulated wastewater, the catalysts could efficiently degrade phenol. The highest removal rate of phenol was approximately 90%.
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