| As a derivative of a conductive polymer polyaniline, N-substituted carboxylicpolyaniline (NPANI) not only has the common properties of the conductive polymer, such asenvironmental stability, fast redox mechanism, strong adhesion to common substrates,additionally, better processability, but also can well composite with other materials. Theseproperties are from its more hydrophilic carboxyl group than aniline monomer. However,N-substituted carboxylic polyaniline, as polyaniline, has poor conductivity and easily lossingactivity at high pH, the composite is an effective ways to overcome it. Graphene (rGO) hashigh electrical conductivity, large specific surface area and controllability of properties. ButrGO prepared by chemical reduction may cause environment problems and may difficult tocontrol the reduction degree. Electrochemical method is a green controllable synthesis method.In this paper, the composite of the two materials, not only can make up for drawback ofindividual components, but also the synergistic effects let the composites have betterperformance than individual components, which can further broaden its application inmodified electrodes. definite studies are as follows:1. The rGO/NPANI composite film modified electrode was constructed successively byelectropolymerization, adsorption, and constant potential reduction method. In addition, thecatalytic performance to nitrite was studied. From the aspects of electrochemical activity andelectrocatalytic activity areas, the number of NPANI electropolymerization, GO concentrationand electroreduction time and pH values was optimized. Results shown that under optimalconditions, the modified electrode exhibit a low oxidation potential to nitrite (0.81V). Thelinear range is1.0×10-6~1.3×10-2M with higher sensitivity (29.18A·mM-1) and thedetection limit of0.30M (S/N=3).2. The second modified electrode was fabricated by dropping the prepared manganesedioxide on the support material consist of graphene and N-substituted carboxylic polyaniline.The strong adsorption of N-substituted carboxylic polyaniline with great surface area and highconductivity of graphene can make manganese dioxide loaded well, improve electrocatalyticproperties of MnO2/rGO/NPANI modified electrode at the same time. Experimental resultsshow that the modified electrode has good catalytic effect to nitrite oxidation. Compared withmanganese dioxide modified electrode, MnO2/rGO/NPANI modified electrode has lowerdetection potential, wider linear range, higher response current and sensitivity to nitrite. Thelinear range is0.5×10-6~5.13×10-2M, the sensitivity is14.08A·mM-1, and the detectionlimit of0.20M (S/N=3). 3. A third modified electrode was constructed to detect nitrite, by the way ofchangeing metal oxide catalysts to loaded rod-like copper oxide on the electrochemicalmethods prepared rGO/NPANI composite film. Due to synergistic effects produced fromeffective composite of the three components, CuO/rGO/NPANI modified electrode has highersensitivity and lower detection limit for detecting nitrite compared with other componentsmodified electrodes. The linear range of CuO/rGO/NPANI modified electrode for detectingnitrite is0.5×10-6~7.4×10-3M and7.4×10-3~2.29×10-2M, the sensitivity is32.32A·mM-1, and the detection limit of0.15M(S/N=3). |
