Synthesis And Properties Of Graphite Carbon Nitride Based Chemical Sensors

In recent years,thanks to the excellent catalytic activity,stability and optoelectronic properties,the novel organic semiconductor material,graphitic carbon nitride?g-C₃N₄?,have become the hotspots in materials and widely used in photocatalysis,biological imaging and other fields.However,the low conductivity and poor dispersibility of g-C₃N₄ greatly limit its application in the field of chemical sensors.This work aims to employ g-C₃N₄ with different morphology to prepare a series of fluorescent sensor and electrochemical sensor combined with optical and electrochemical technology,to achieve the quantitative detection of energetic materials and biological small molecules.This rapid,sensitive,and simple detection method has a good future in the field of environmential monitoring and food safety.The specific contents are as follows:1.The g-C₃N₄ quantum dots?CNQDs?/Poly?3,4-ethylenedioxythiophene??PEDOT?composite was constructed by a facile co-deposited method.The electrochemical behaviors of modified electrodes were investigated by cyclic voltammetry and electrochemical impedance method,which exhibited the PEDOT/CNQDs/GCE not only has an excellent electro-catalytic ability but also has a good response to ascorbic acid?AA?.The limit of detection is 6.38?M.2.A novel PEDOT/g-C₃N₄ nanofibers?h-CN?hybrid film was directly electrodeposited on the GCE.The scanning electron microscope and infrared spectrum of the as-obtained film revealed that PEDOT grew well on the surface of h-CN.The electrochemical experiments demonstrate that PEDOT/h-CN/GCE possess excellent electrochemical properties and exhibit a significant catalytic effect on the electrochemical oxidation of ascorbic acid and acetaminophen?AP?.The modified electrode can be used for electrochemical simultaneous detection of AA and AP,and the detection limits are 1.51?M and 0.49?M,respectively,also showing good stability,reproducibility and selectivity.3.The porous g-C₃N₄?PCN?was prepared by a one-step acid etching and ultrasonication process.The PCN and MWCNT composite was modified on the electrode by adsorption method.The electrochemical experiments showed that MWCNT/PCN/GCE have an obvious catalytic effect on the electrochemical oxidation of UA.Differential pulse voltammetry was used to detect UA with a detection limit of 0.139?M.Moreover,the sensor can be used to detect UA in human serum.4.The ultrathin g-C₃N₄ nanosheets?A-CNNs?were prepared by thermal oxidation and acid etching.The morphology,crystal and molecular structure of g-C₃N₄ produced in different stages were analyzed by transmission electron microscopy,X-ray diffraction and infrared spectroscopy.The results show that the thinner layered g-C₃N₄ is obtained by acid etching.The quenching mechanism of trinitrophenol?TNP?on fluorescent probe A-CNNs solution was investigated by fluorescence emission intensity and fluorescence lifetime measurements.Quantitative detection of TNP in aqueous solution was realized,and the detection limit was4.79 nM.