Hydrothermal synthesis of cysteamine capped CdTe quantum dots and its photoluminescence response to Ag (I)

In order to study quantum dots (QDs) fluorescence analysis method using for the detection of metal ions, three sizes of water-soluble cysteamine (CA) capped CdTe QDs have been synthesized by hydrothermal synthesis method and characterized by UV-visible spectrophotometer and fluorospectro photometer. The photoluminescence (PL) response of CA capped CdTe QDs with particle size 3.49 nm to Ag⁺ has been studied. The results indicate that Ag⁺ has a great effect on the PL of CA capped CdTe QDs. In the presence of lower concentration of Ag⁺, the CdTe QDs exhibite PL enhancement, which is the result of the absorbed Ag⁺ passivating the traps on the particle surface of CdTe QDs. However, the PL of CdTe QDs shows obvious quenching with the further increase of Ag⁺ concentration, which indicates that the excess Ag⁺ facilitates nonradiative recombination and happens electron transfer with CdTe QDs after saturating the surface trap. When Ag⁺ concentration is in the range of 4.0×10^-6 ~18.4×10^-6 mol·L^-1, the linear equation is F₀-F=335.5174C+364.97436 (C=10^-6 mol·L^-1). And the detection limit is 1.974×10^-8 mol·L^-1. Based on the PL response of CA capped CdTe QDs to Ag⁺, we can use the CA capped CdTe QDs to selectively detect Ag⁺.