| Electrochemical sensor is one of the unit which have many advantages such as high stability, rapid analysis, easy operation, high sensitivity and low cost and so on. It has been one of the most attractive methods. However, one of the main challenges in the electrochemical sensor is the search for and application of proper electrode modifier materials. Similar to graphite, ultrathin graphitic carbon nitride（g-C3N4） has attracted great attention because of its unique electronic band structure, high thermal and chemical stability, and catalytic properties. In this dissertation, ultrathin graphitic carbon nitride（g-C3N4）was prepared and then employed as sensing materials.This work reports this sensitive sensor for the electrochemical determination of trace mercury（Hg2+）,copper（II） and tryptophan（Trp）. The main work is as follows:Firstly, The bulk g-C3N4 was synthesized by direct thermal polycondensation of melamine and then was ultrasonicated in water to get utg-C3N4 nanosheets. The phase composition of the as-synthesized g-C3N4 was characterized by X-ray diffraction（XRD）,transmission electron microscope（TEM）, Fourier transform-infrared spectroscopy（FTIR）, X-ray photoelectron spectroscopy（XPS）, atomic force microscope（AFM）. The results prove that utg-C3N4 is the layer structures and there is many functional groups.Secondly, ultrathin graphitic carbon nitride（g-C3N4） modified glassy carbon and then the electrochemical behaviors of mercury（Hg2+） were investigated. Under the optimized experimental conditions, the utg-C3N4/GC electrode could detect Hg2+at concentration as low as 0.023 mg/L with linear range of 0.1–15 mg/L.it was employed to determine the mercury（Hg2+） in real sample.Thirdly,the electrochemical sensor can determinate tryptophan（Trp）.Under the optimized experimental conditions, the linear range of Trp is 1.0×10-7–1.1×10-4M and detection limit is 2.4×10-8 M.Finally, the electrochemical sensor was used for detecting copper（II）.Generally speaking, in process of the fabrication of electrochemical sensor,utg-C3N4 nanosheets is an excellent candidate. In summary, utg-C3N4/GC provided a new method for the detection of trace mercury（Hg2+）, copper（II）and tryptophan（Trp）. |
