One-step hydrothermal synthesis of thioglycolic acid capped CdS quantum dots as fluorescence determination of cobalt ion

Zhezhe Wang,Rongjun Zhao,Tong Zou,Yude Wang,Xinxin Xing,Yue Yang,Zidong Wang

doi:10.1038/s41598-018-27244-0

Abstract

Highly luminescent CdS quantum dots capped with thioglycolic acid (TGA@CdS QDs) were synthesized from cadmium chloride and thiourea as cadmium and sulfur sources via simple hydrothermal method. The room temperature photoluminescence (RTPL) properties of TGA@CdS QDs were investigated. The results indicate that the polarity of the solvent and the surface trap state resulted in the broadness Stokes shift between the maximum absorption wavelength and the emission wavelength of TGA@CdS QDs. The Co2+ sensing properties of fluorescence determination were investigated using TGA@CdS QDs. The as-synthesized CdS QDs exhibits the excellent selectivity and sensitivity of fluorescence quenching for cobalt ion (Co2+). The limit of detection (LOD) is as low as 0.05 μM which is much lower than maximum limit of cobalt ions in drinking water. The linear response range of Co2+ was from 0.5 to 80 μM. The sensing system revealed the advantages of low detection limit, excellent selectivity, high sensitivity, convenience and low cost. The color change of CdS QDs shows potential applications in the detection of Co2+.

Highlights

Luminescent CdS quantum dots capped with thioglycolic acid (TGA@CdS QDs) were synthesized from cadmium chloride and thiourea as cadmium and sulfur sources via simple hydrothermal method
The absence of distinct S-H characteristic band of TGA at 2600–2550 cm−1 confirms the capping of CdS QDs which is due to covalent bond between cadmium of CdS and sulfur of TGA32
One part sulfur forms CdS QDs with cadmium, the other belongs to TGA which capped on the CdS QDs surface

Summary

Introduction

Luminescent CdS quantum dots capped with thioglycolic acid (TGA@CdS QDs) were synthesized from cadmium chloride and thiourea as cadmium and sulfur sources via simple hydrothermal method. CdS QDs. The as-synthesized CdS QDs exhibits the excellent selectivity and sensitivity of fluorescence quenching for cobalt ion (Co2+). Some papers have reported that heavy metal ion, such as Hg2+, Ag+, Cu2+, Co2+and Ni2+, have been detected by surface-modified CdS QDs based on the gradual quench of the fluorescence intensity of the QDs25–28.

Results

Conclusion