中文摘要：

为了研究氮源种类对氮掺杂碳点（NCDs）结构、荧光性能及Hg（2＋）检测选择性和敏感性的影响,以课题组前期柠檬酸为碳源,尿素和氨水分别为氮源,一步水热法制备的NCDs为研究对象,分析了氮源种类对NCDs结构、荧光性能以及Hg~（2＋）检测选择性和敏感性的影响规律。结果显示：这两种氮源对所制备NCDs的碳化度、氮掺杂度、表面官能团、粒径、量子产率有明显影响,但对紫外可见吸收和荧光光谱基本没有影响。将这两种NCDs作为荧光探针检测Hg~（2＋）具有相似的高选择性,但以氨水为氮源制备的NCDs检测Hg~（2＋）具有更低的检测极限和更宽的线性范围,即：氮源的含氮量越高,制备的NCDs的氮掺杂度和表面的氨基、酰胺键越多,活性位点越多,当NCDs与Hg~（2＋）进行络合作用时,络合位点更多,所以检测Hg~（2＋）更敏感。

英文摘要：

To study the effect of the kind of nitrogen source on the structure and fluorescence properties of nitrogen-doped carbon dots（NCDs）and the selectivity and sensitivity of NCDs towards Hg~（2＋）detection,this paper aims at the preparation of NCDs on the basis of preliminary researches in our group,in which NCDs were synthesized by a one-step hydrothermal method using citric acid as carbon source,urea and ammonia solution as nitrogen source,respectively.The effect of nitrogen source on the structure,fluorescence properties of NCDs and the selectivity and sensitivity of NCDs towards Hg~（2＋）detection was investigated by high-resolution transmission electron microscopy,X-ray diffraction,Fourier transform infrared,X-ray photoelectron spectroscopy,elemental analysis,ultraviolet-visible absorption and photoluminescence.Results show that different nitrogen sources have obvious effect on carbonization degree,nitrogen doping degree,surface functional groups,particles size and quantum yield,but less influence on ultraviolet-visible absorption and photoluminescence spectra.The two kinds of NCDs used for fluorescence probe exhibit similar high selectivity towards Hg~（2＋）.However,the NCDs prepared by using ammonia solution as nitrogen source,possess lower limit of detection and wider linear range for Hg~（2＋）detection.That is to say,higher nitrogen content of nitrogen source could contribute to higher nitrogen doping degree of NCDs,and more amino and amide bonds on the surface of NCDs,which lead to more active sites of NCDs.When NCDs and Hg~（2＋）are complexed,the NCDs can exhibit highly sensitive detection of Hg~（2＋）because of more complexation sites.