以通过氢键形成分子单元的异硫氰酸胍为掺杂剂, 采用一锅水热法制备了具有明亮蓝色荧光的S、N共掺杂碳点.结构表征显示, N和S元素能够通过杂环原子和碳点表面官能团的形式充分掺杂.该碳点溶液的光致发光最佳激发波长为395 nm, 对应发射谱从“激发独立”变为“激发依赖”.在碳点的形成过程中, 出现了一些分子级荧光团, 随着碳化过程以表面官能团的形式键合在碳点的表面, 这为该碳点作为银离子检测的传感探针提供了可能.碳点溶液荧光强度和银离子浓度在不同浓度范围内成线性关系, 基团－S－C≡N能够促进银离子对碳点溶液荧光的猝灭效应.该碳点溶液制备方法简单、性能优异, 为高效检测工业污染物中银离子的应用提供了一种可能的途径.

N and S co-doped carbon dots with bright blue emission have been synthesized by a facile one-pot hydrothermal treatment. A specific compound, guanidine thiocyanate via a hydrogen bond to form the molecule unit, was chosen as the dopant. In the structure characterization, N and S elements could be sufficiently doped by means of the heteroatom or the functional groups bonded on the surface of carbon dots. The results of the photoluminescence spectra indicated a change of emission process from excitation-independent to excitation-dependent with the optimal excitation wavelength at 395 nm, suggesting that some small fluorophore molecules exist in citric acid-derived carbon dots solution and bond on the surface of the carbon dots after carbonization in view of the triexponential feature of fluorescence lifetimes of carbon dots. Now that so many fluorophores attach on the carbon dots surface, the as-prepared carbon dots were used as a sensing probe for the detection of silver ion. As expected, the changes of fluorescence intensities were linearly proportional to the different concentration ranges of silver ion. The －S－C≡N group could accelerate the quenching of carbon dots towards silver ion. The facile preparation method and high performace of as-prepared carbon dots provide a possible approach for efficient detection of silver ion for the application in industrial pollutants.