| With the rapid development of nanoscience and nanotechnology, carbon related nanostructures have attracted extensive interests, especially after the discovery of fluorescent carbon nanoparticles, carbon nanotube, fulleren and graphene. Graphene is a flat monolayer of carbon atoms tightly packed into a two-dimensional (2D) honeycomb lattice, which can be considered as a basic building block for other carbon-based materials including 0D fullerenes, 1D carbon nanotubes and 3D graphite. These carbon-based materials possess outstanding and unique physical, chemical and mechanical properties, and have been widely applied in the design of devices of micro-nano-electronics, optoelectronics, novel composite materials and sensing materials. At present, the researches related to graphene have become the one of hottest research point in the field of electrochemistry. Compared with the conventional quantum dot based on sulphides, selenides, or tellurides of zinc and cadmium, fluorescent carbon nanoparticles (CNPs) are more promising for the application in biology labelling and life science due to their excellent properties, such as low cytotoxicity, biocompatibility, and chemically inert. Therefore, it shows a great significance in studying the method for preparing the fluorescent carbon nanoparticles.In this thesis, studies on the method to prepare graphene and the electrochemical properties of graphene and graphene-based composite materials were carried out. Meanwhile, the fluorescent carbon nanoparticles were prepared by electrochemistry method. The main points of this thesis are briefly summarized as follows:1) The method of reducing oxided-graphene was employed to prepare graphene. Scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared spectroscopy (FT-IR), Raman spectroscopy and other characterization techniques were employed to characterize the graphene. The graphene provide a potential application in preparing and designing new electrochemical sensors and electrocatalysis material.2) Highly efficient and large-scale synthesis of graphene from graphite through electrolytic exfoliation in the ionic liquid electrolyte was introduced. SEM and AFM confirmed the existence of monolayer graphene sheets and stacks containing a few graphene sheets. Raman spectroscopy demonstrated that the as-prepared graphene sheets have low content defect. FT-IR spectra showed that graphene did not contain oxygen-containing functional groups, such as: carboxyl, hydroxyl, carbonyl, etc. In contrast to micromechanical exfoliation, electrolytic exfoliation can be scaled up for large-scale and continuous production of graphene. In addition, differential pulse voltammetry (DPV) was used in simultaneous detection of dopamine (DA), ascorbic acid (AA) and urine acid (UA). DPV data indicated the superiorly electrocatalytic ability of the graphene. A novel graphene-based pH sensor was successfully fabricated by using graphene film. The open-circuit potential of graphene/AuE in different pH B-R buffer solution showed that the graphene/AuE can be used as a pH sensor with a linear range of pH 3.011.0 and a sensitivity of 53.88 mV/pH.3) Fast and facile preparation of blue-green fluorescent carbon nanoparticles through electrochemical oxidation of graphite in ethanol was introduced The nanoparticles are characterized by Transmission electron microscopy (TEM), FT-IR, Raman and other techniques. Surface energy traps were created on the carbon nanoparticles and resulted in the visible light emission due to the quantum confinement effects. Fluorescent carbon nanoparticles take on great potential in the application in biology labelling and life science due to their many advantages such as low cytotoxicity, biocompatibility, and chemically inert.4) Graphene nanosheets modified glassy carbon electrode (GNs/GCE) was fabricated as voltammetric sensor for determining rutin with good sensitivity, selectivity and reproducibility. The sensor exhibits an adsorption-controlled, reversible two-proton and two electron transfer reaction for the oxidation of rutin with a peak-to-peak separation (?Ep) of 26 mV as revealed by cyclic voltammetry. Moreover, the redox peak current increased about 14 times than that of bare glassy carbon electrode (GCE). The linear response of the sensor is from 1×10-7 to 1×10-5 M with a detection limit of 2.1×10-8 M (S/N=3). The method was successfully applied to determine rutin in tablets with satisfied recovery.5) A highly sensitive and selective voltammetric sensor for simultaneous determination of hydroquinone (HQ) and catechol (CC) was developed by modifying a glassy carbon electrode with graphene nanosheets (GNs/GCE). Separation of the oxidation peak potentials for HQ and CC was about 112 mV in 0.10 M acetate buffer solution (pH 4.5), and the anodic currents for the oxidation of both HQ and CC are greatly increased at GNs/GCE, which makes it suitable for simultaneous determination of these compounds. Under the optimized conditions, the anodic peak current of HQ is linear with the concentration of HQ from 1×10-6 to 5×10-5 M in the presence of 5×10-5 M CC. A detection limit of 1.5×10-8 M (S/N=3) can be achieved. At the same time, the anodic current of CC is linear with the concentration of CC from 1×10-6 to 5×10-5 M with a detection limit of 1.0×10-8 M (S/N=3) in the presence of 5×10-5 M HQ. The proposed sensor was successfully applied to the simultaneous determination of HQ and CC in tap water, and the results are satisfactory. |
PDF Full Text Request