| As a type of neurotransmitter,ascorbic acid(AA)is an indispensanle component in biological fluids and brain functions.Many diseases,such as scurvy,osteoporosis and urolithiasis,are directly related to changes in the concentration of AA.Therefore,the accurate determination of AA is still a research hotspot.The electrochemical method using chemically modified electrodes is considered to be an effective method for detecting AA.However,the morphology of the electrode surface material is directly related to the performance.The traditional methods for preparing polyaniline-based electrodes have certain defects in the aspect of morphology control,which hinders the performance of the electrode.Therefore,choosing an appropriate method to adjust the morphology of polyaniline on the modified electrode surface is of great significance to the electrochemical performance and detection performance of the electrode.(1)In this paper,camphor sulfonic acid(CSA)was selected as the dopant to obtain four kinds of polyaniline(PANI)with different morphologies through the chemical oxidation polymerization of aniline(An).Then four kinds of PANI with different morphologies were deposited by electrophoretic deposition technology on the surface of indium tin oxide conductive glass(ITO),so PANI modified electrodes were prepared.Through the characterization of the morphology for the materials and the electrodes,it was found that four kinds of morphologies of PANI remained on the electrode surface after electrophoretic deposition.At the same time,the test of PANI dispersed in formic acid and formic acid/acetonitrile system found that:PANI with four different morphologies undergo the same morphology decomposition process,and under the direct current electric field,they were recombined into their original morphologies on the electrodes surface.The electrochemical test found that the PANI nanotube electrode had the best electrochemical performance.When the PANI nanotube electrode was used to detect AA,the sensitivity is 574.13 μA·mM-1·cm-2,and the detection limit is 0.69μM.(2)On the basis of pure PANI,high-conductivity spherical gold nanoparticles(AuNPs)were introduced,and PANI/AuNPs composite materials with amorphous structure were synthesized by chemical oxidation polymerization.PANI/AuNPs modified electrodes were prepared by electrophoretic deposition.The electrochemical performance test of PANI/AuNPs electrodes with different ratios of AuNPs to An showed that:when mAuNPs:mAu=0.03:1,the electrochemical performance of PANI/AuNPs-3 electrode was the best.At the same time,the PANI/AuNPs modified electrodes were used for AA detection.The chronoamperometry test showed that the sensitivity of the PANI/AuNPs-3 modified electrode can reach up to 799.6μA·mM-1·cm-2.The line range is 5.0μM～6.5 mM,and the detection limit is as low as 0.26 μM.Moreover,the presence of dopamine has little effect on the detection of AA.The high conductivity and good catalytic performance of spherical AuNPs make the PANI/AuNPs modified electrode possess such a good electrochemical performance and excellent sensing detection performance.(3)The mass ratio of gold nanords(AuNRs)to aniline was selected to be 0.03:1,and the PANI/AuNRs composite material with nanorod structure was synthesized through the template orientation of AuNRs.Then,the PANI/AuNRs modified electrode with nanorod structure was successfully prepared by electrophoretic deposition.By characterizing the morphology of PANI/AuNRs in formic acid/acetonitrile system,it was concluded that electrophoretic deposition was also suitable for the morphology control of polyaniline composite materials electrodes.The sensitivity of PANI/AuNRs electrode to detect AA is 872.7μA·mM-1·cm-2,and the detection limit is 0.18 μM.Compared with the PANI/AuNPs electrode,the excellent performance of the PANI/AuNRs electrode is mainly due to its nanorod structure which provides a good channel for the transport of electrolyte solution and electrons. |
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