Study Of Detecting Electroactive Materials Based On Graphene And Graphene Composite Materials

Graphene(reduced graphene oxide, denoted as RGO), an ideal two-dimensional layered material, has recently attracted a great attention in electrochemistry because of its large specific surface area, unique mechanical properties, high electrical conductivity and rapid heterogeneous electron transfer. Determining electroactive materials by graphene and graphene-based composites has been carried out widely. In this paper, dopamine(DA), uric acid(UA), ascorbic acid(AA) and nitrite were detected by the glassy carbon electrode(GCE) modified with graphene or graphene-based composites. These molecules play pivotal roles in the physiological activity of human body, so it is significant to detect the concentrations of them accurately. The main contents of this thesis are as follows:1. The RGO was fabricated on GCE by a simple electrochemical method for detecting DA, UA and AA. The RGO with many wrinkles covered on the surface of GCE completely. In the electrochemical characterization, RGO enhanced electron transfer activity because of its great electric conductivity and the ultrahigh surface area. Compared with the bare GCE, the clear and well-separated electro-oxidation peaks of DA, UA, and AA at RGO/GCE were observed simultaneously. In addition, it was proved that GCEs modified with different amounts of RGO have obvious influence on DA, UA and AA detection results. The modified electrode exhibited high selectivity and good reproducibility towards the determination of DA, UA and AA with low detection limit and wide detection range. The fabrication of RGO/GCE is simple, cost-effective, and user-friendly and it is expected to have good application prospects.2. The flower-like RGO nanosheet clusters(f-RGO) were facilely fabricated on GCE by electrochemical method, and the obtained f-RGO was applied for DA detection. The f-RGO with macroporous structure distributed evenly on GCE as characterized by SEM. The current response of f-RGO/GCE for the determination of DA was higher than that of other electrodes(GCE and RGO/GCE), which was attributed to the high accessible surface area of f-RGO. The DPV response of DA on f-RGO/GCE showed a wide liner range, low detection limit and a good discrimination between DA, UA and AA. The fabrication of f-RGO/GCE is simple, cost-effective, and user-friendly.3. A facile and low-cost electrochemical method was developed for the preparation of 3D flower-like RGO nanosheets on GCE which was then employed as the support material for electro-deposition of Cu particles to fabricate a sensor for nitrite determination. The prepared Cu/f-RGO/GCE exhibited excellent electrocatalytic capability for the reduction of nitrite compared with Cu/GCE and Cu/ RGO/GCE in CV curves. While in the determination of nitrite the prepared sensor possessed a wide liner range, a low detection limit, excellent reproducibility, nice stability and remarkable anti-interference ability. These results demonstrated the special electrochemical characters of flower-like RGO nanosheets. This work provides a simple and cost-effective approach which is expected to have promising application prospects.