“On-Off-On” fluorescence sensor based on g-C3N4 nanosheets for selective and sequential detection of Ag+ and S2-

Publication date: 1 June 2017
Source:Talanta, Volume 168
Author(s): Shan Wang, Qian Lu, Xu Yan, Mingming Yang, Ranfeng Ye, Dan Du, Yuehe Lin
Detection of silver (Ag⁺) and sulfide (S²⁻) ions is important because their presence in large amounts can cause many diseases. In this study, a novel, simple, "on-off-on" fluorescence sensor based on g-C3N4 nanosheets for sequential detection of Ag⁺ and S^2- was designed. The fluorescence signal of the g-C3N4 nanosheets is quenched because Ag⁺ chelates with the N of the g-C3N4 nanosheets, leading to photoinduced electron transfer from the sheets to Ag⁺. After adding S²⁻, the fluorescence of the g-C3N4 nanosheets is recovered due to formation of Ag2S, which activates the fluorescence of the g-C3N4 nanosheets. The recovery efficiency was found to increase with increasing concentrations of S^2-, with linear calibration ranging from 0nmol/L to 30nmol/L. Other potentially interfering species, such as SO4²⁻, PO4³⁻, HPO4²⁻, H2PO4⁻, CO3²⁻, NO3⁻, Ac⁻, and HCO3⁻, presented negligible effects on S²⁻ detection. Moreover, the proposed sensor exhibited several advantages, including low cost, easy preparation, rapid detection, excellent biocompatibility, and a switchable fluorescence response. These attributes make this fluorescent sensor a promising tool for environmental applications.

Graphical abstract

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