Detection Methods And Mechanism Of Electroactive Compounds Based On Graphene And PEDOT/Graphene Electrodes

Dopamine(DA),uric acid(UA),tyrosine(Tyr)and hydrochlorothiazide(HCTZ)are common electricactive compounds.In this paper,a novelgrapheme-based electrochemical sensor was developed,and the analysis method and mechanism for simultaneous detect DA,UA,Tyr and HCTZ.Graphene/tantalum(Ta)as a sensing electrode which can simultaneously detect DA,UA,Tyr and HCTZ via differential pulse voltammetry(DPV)of electrochemical analysis method.For the simultaneous determination of DA,UA,Tyr and HCTZ,the peak potential differences between adjacent analytes are 0.132 V(DA and UA)and 0.28 V(UA and Tyr).The linear ranges of DA,UA,Tyr and HCTZ are 0.3-40,0.3-400,3-800 and 0.5-500 ?M,the detection limits are 0.04,0.1,0.6 and 0.4 ?M,respectively.These results indicate that the graphene/Ta is a promising electrochemical sensing electrode,which has the advantages of high sensitivity,good selectivity and stability.Characteristics of graphene layers can be analyzed by electronic scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD),electrochemical impedance(EIS),and cyclic voltammetry(CV)methods.Graphene was grown vertically on Ta substrate by direct current arc plasma chemical vapor deposition(CVD).Vertical graphene as the sensitive material has a very large active surface area,high conductivity and a large number of electric catalytic active site,can distinguish the four compounds and simultaneous quantitative analysis.Dihydroxybenzene have three isomers,including hydroquinone(HQ),catechol(CC)and resorcinol(RC).The traditional detection methods are difficult to distinguish them.Aseries of poly(3,4-ethylenedioxythiophene)-graphene composites have been systhesized by in-situ polymerization of 3,4-ethylenedioxythiophene on graphene nanosheets.Diameter of one-dimensional(1D)PEDOT structures was about 200 nm,its length reaches several microns,PEDOT/graphene sensing electrode can distinguish between HQ and CC,RC and nitrite.Peak potentials of HQ,CC,RC and nitrite were located at 12 mV,120 mV,512 and 700 mV,respectively,the peak potential differences are more than 100 mV,the detection limits are 0.06,0.04,0.15 and 5 ?M.The PEDOT/graphene sensing electrode exhibited high electric catalytic activity and selectivity,rapid response capability and long life.These advantages due to one dimensional form large specific surface area,unique hybrid structure generates electrical properties and chemical stability.