Construction And Application Of Graphene/Ionic Liquid Composite Sensors

With the enhancement of people's awareness of environmental protection and health,the demand for highly selective and sensitive detection methods has increased rapidly in recent years.Compared with spectroscopy and chromatography,electrochemical sensors are inexpensive,simple,suitable for demanding environments that require robust,compact analytical methods.Therefore,the field of electrochemical sensors has become a research hotspot in recent years.In the research of electrochemical sensor materials,graphene-based ionic liquid composites have been widely applied in the field of electrochemical sensors due to their unique physicochemical advantages.In this paper,sensitive detection of ascorbic acid,nitrite and dopamine was achieved by constructing three kinds of nano-modified electrodes.The main contents are as follows:1.Construction and application of a highly sensitive ascorbic acid sensor based on ionic liquid functionalized graphene nanocompositesAn electrochemical sensor for the detection of ascorbic acid at room temperature by coating the graphene oxide ionic liquid sensitive layer is prepared.The addition of ionic liquid can not only enhance the electrical conductivity of graphene oxide,but also improve the dispersibility of graphene oxide.GO-IL nanocomposites have the large electroactive surface area and good sensitivity.The experimental result shows that the GO-IL electrochemical sensor has a low detection limit of 3.33 ?M(?mol·L-1).The preparation of electrochemical sensor is simple,economical,sensitive and can be widely applied to the determination of AA in drug samples.2.Construction and application of nitrite electrochemical sensor based on sulfur-doped graphene ionic liquid compositesHydrothermal synthesis combined with ultrasonic assisted method was used to prepare sulfur-doped graphene ionic liquid composite(SG-IL).And then the highly sensitive electrochemical sensors are assembled using SG-IL.The morphology andstructure of the composites were characterized by scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FT-IR).Electrochemical analysis shows that the nitrite concentration shows a good linear relationship in the range of 3-200 ?M with a detection limit of 1.0 ?M(signal-to-noise ratio of 3).The results show that the sensor has good selectivity,high sensitivity,low detection limit and ideal test results.It can be used as a detection platform for nitrite in actual water samples.3.Construction and application of dopamine electrochemical sensor based on graphene ionic liquid-silver nanocompositesComposite materials were prepared by doping silver nanoparticles with ionic liquid graphene,and then electrochemical sensors were assembled for sensitive detection of dopamine.Before the quantification,the parameters involved in the experiment(material dispersion ratio,dripping amount,pH,enrichment potential and enrichment time)were optimized.And the quantitative study was carried out by amperometric(i-t)under the optimal parameter conditions.The results show that the electrochemical sensor has a linear range of 0.75~250 ?M and the detection limit of0.25 ?M(S/N=3).Furthermore,the electrochemical sensor showed good selectivity,sensitivity and stability when used for the real sample detection of dopamine hydrochloride injection.