| This thesis involves two parts: Part one Documents reviewChemically modified electrodes(CMEs)are currently an active area of electrochemical and electroanalytical research.By tailoring the electrode surface,it can endow the electrode with special properties and realize the electrocatalytic reactions unreacted on the traditional electrode.New materials currently bring the newly developmental power to CMEs.Among them,nanomatermials and ionic liquids with uniquely chemical and physical properties undergo intense investigation and are widely applied in electrocatalytic and electroanalytical chemistry.In this mini-review,the preparation of CMEs and the application of nanomaterials and ionic liquids in CMEs are reviewed. Part two Research reportsIn this thesis,Co3O4 nanoparticles(nano-Co3O4)and 1,2-ethyl-3-H-benzimidazolium-tetrafluoroborate ionic liquid([HeeBim][BF4],IL)were chosen as modifiers.Nano-Co3O4 modified carbon paste electrode(nano-Co3O4/CPE)was prepared and used to study the voltammetric behavior of xanthine(XA).On the other hand,the[HeeBim][BF4]intercalated wax-impregnated graphite electrode(IL-WGE)was prepared by rubbing the[HeeBim][BF4] onto the electrode surface.The voltammetric behaviors of XA and calcium dobesilate(CD)at IL-WGE were investigated.In addition,the zero current potentiometry was used to in-situ track of the self-assembly process of L-cysteine on gold surface is proposed.The concrete contents are given as follows:(1)In 0.1 mol/L HAc-NaAc buffer(pH 5.6),a sensitive oxidation peak of XA was observed at +0.805 V at activated nano-Co3O4/CPE.The peak potential was negatively shifted about 80 mV,and the peak current was enhanced approximately five-fold in compared with those at CPE.The results showed that the activated nano-Co3O4/CPE exhibited significantly electrocatalytic action toward the oxidation of XA,but non-activated nano-Co3O4/CPE only possessed weakly one.The electrocatalytic action was attributed to the increase of efficient electrode surface and both adsorptive and coordination action of Co(OH)2 nanoparticles transformed from nano-Co3O4 during activation process.(2)IL-WGE was characterized by using Fe(CN)63-and Cu(NH)3))42+as probe ions.The voltammetric behavior of XA at IL-WGE was investigated,and the electrochemical kinetics parameters,such as electron transfer coefficient 13 and the electrode reaction rate constantκf, were obtained.The results demonstrated that IL-WGE can adsorb cations by the electrostatic action.The peak current of XA at IL-WGE was enhanced approximately three-fold,and the peak potential was negatively shifted about 30 mV in compared with those at WGE.The electron transfer coefficient 13 of XA at IL-WGE was 0.231,and the electrode reaction rate constantκf was 1.35x10-1cm/s,which was three-fold in compared with that at WGE.Based on this,a new voltammetric method for determination of XA was proposed.(3)The voltammetric behavior of calcium dobesilate(CD)at IL-WGE was investigated. The results show that the oxidation peak current of CD at IL-WGE was enhanced two-fold, and the peak potential was negatively shifted about 170 mV in compared with those at WGE. The electron transfer coefficientβof CD at IL-WGE was 0.220,and the electrode reaction rate constantκf was 5.83×10-2cm·s-1,which was two-fold in compared with that at WGE. Based on the sensitive oxidation peak of CD at IL-WGE,a linear sweep voltammetric method for determination of CD was developed.A linear range of 2.0×10-7～2.0×10-5mol·L-1was obtained along with a detection limit of 8×10-8mol·L-1.(4)The zero current potentiometry was used to investigate the self-assembly process of L-cysteine on gold surfaces.With self-assembly time prolonging,the Epzcgradually shifted from a constant value to another constant value.Based on the change of the Epzcwith self-assembly time,the self-assembly process of L-cysteine on gold surfaces was tracked in situ,and the adsorption rate constant was approximately calculated as 3.69×103 M-1s-1. Experiments demonstrated that the experimental parameters,such as reproducible detections, ranges of potential and scan rate,didn't influence the self-assembly process and track process. The approach showed obvious advantages in sensitivity over cyclic voltammetry and in simplicity over other methods.
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