Electrochemical Synthesis And Properties Of RGO/polyphenothiazide Composite Electrodes

As the development of economy and science and technology,more and more daily necessities go into people's life.However,the safty of commodities has become the hot spots of people's increasing concerns.Therefore,the detection of trace amounts of harmful substances in commodities has converted into the most urgent task for scientific workers.In recent years,conducting polymers,having extensive conjugated main chain and semiconductor or conductor nature after doping,have been applied widely in the chemical,bilogical and electrochemical sensors and show extremely good detection effects.However,the relatively low conductivity of conductive polymer?<10^-77 S/m?limits their pratical applications.On the other hand,graphene has been used in many fields such as supercapacitors,batteries,sensors and electrochemical catalysis,due to its excellent thermal stability,chemical stability,outstanding electronic transmission capacity and large specific surface area.Therefore,in order to further improve performance of conductive polymer,it is necessary to combine a conducting polymer with graphene taking into account the synergistic effect between the both.Moreover,sensors can be fabricated by the proposed binary composites.The main contents of this thesis are shown as follows:1.Preparation and electrochemical properties of graphene/poly?N-methylthinone?composite electrodeThe experiment was conducted by a two-step synthesis process.Firstly,the reduced graphene oxide was obtained on the surface of a glass carbon electrode via electrochemical reduction.Then,poly?N-methylthinone?was deposited on the reduced graphene oxide modified electrode to form a reduced graphene oxide/poly?N-methylthinone?composite.Scanning electron microscope?SEM?,UV-visible spectroscopy?UV-Vis?,Fourier transform infrared spectrometer?FTIR?,Raman spectroscopy?Raman?and X-ray photoelectron spectroscopy?XPS?were performed toinvestigate surface moephology and stucture of the prepared composite.Compared to poly?N-methylthinone?modified electrode,the obtained composite modified electrode shows a better electrochemical activity in a 0.2 mol·L^-1 PBS solution of different pH values?1.0-12.0?.The results of electrochemical impedance spectroscopy showed that the conductivity of the composite modified electrode was significantly higher than that of the polymer,demonstrating that the?-?interaction between reduced graphene oxide and aromatic ring in conductive polymer chains enhanced the electrochemical activity and conductivity of the polymer.2.Hydroquinone electrochemical sensor based on reduced graphene oxide/poly?N-methylthinone?compositeA reduced graphene oxide/poly?N-mehylthinone?composite electrode was prepared by electrochemical reduction/polymerization and applied in trace detection of hydroquinone.These results obtained from cyclic voltammetry and differential pulse voltammetry showed that due to the synergistic effect between reduced graphene oxide and poly?N-methylthinone?,the as-prepared composite modified electrode exhibited an excellent electrochemical catalytic performance for the hydroquinone detection.Moreover,catechol,a primary isomer of hydroquinone,did not interfer with the determination of hydroquinone,indicating the obtained composite modified electrode possessed a very outstanding selectivity.3.Synchronous electrosynthesis and electrochemical properties of reduced graphene oxide/poly?azure B?compositeReduced graphene oxide/poly?azure B?composite modified electrode was synchronously electrosynthesized by cyclic voltammetry in an 0.2 mol·L^-1 PBS solution with pH 6.0 containing graphene oxide and azure B in the potential range from-1.4 to 1.4 V.Scanning electron microscope?SEM?,Fourier transform infrared spectrometer?FTIR?and X-ray photoelectron spectroscopy?XPS?were conducted to characterize surface morphology and structural properties of the composite.The resultant composite modified electrode showed a high electrical activity in a 0.5mol·L^-1 Na₂SO₄ solution of various pH values?1.0-11.0?.Both the oxidation peak and reduction peak currents were linearly increased with the square root of scanning rates,indicating that the electrode reaction was a diffusion-controlled process.4.Non-enzymatic ascrobic acid sensor based on a synchronous electrosynthesized reduced graphene oxide/poly?azure B?compositeA synchronously electrosynthesized reduced graphene oxide/poly?azure B?composite was used as a non-enzymatic ascrobic acid sensor.The result of cyclic voltammetry showed that the resulting composite modified electrode could effectively catalyze the redox reaction of ascrobic acid in an aqueous solution.The result of chronometric current test also showed that reduced graphene oxide/poly?azure B?composite electrode had an excellent electrochemical catalytic ability to the ascorbic acid redox reaction and therefore could be used to detect ascorbic acid.More importantly,the composite modified electrode showed a very outstanding specificity and selectivity for ascrobic acid in the presence of dopamine and uric acid.