Dopamine And Hydrogen Peroxide Sensing Based On Nanomaterials Modified Microcavity Electrodes

Microcavity electrode has been studied in Electro-analytical chemistry comprehensively andintensively owing to its intrinsic advantages such as electrochemical properties, high spatiotemporalresolution in real-time amperometric monitoring of neurotransmitters and small size. This dissertation isdedicated to sense dopamine and hydrogen peroxide by modifying microcavity electrode with ionicliquid, metal nanoparticles and carbon nanotubes. The dissertation is composed of five chapters.In the first chapter, the research process of dopamine and hydrogen peroxide were introducedfirstly. Secondly, the theory of ultramicroelectrodes and their applications in detecting dopamine andhydrogen peroxide were summarized. Thirdly, the applications in electrode modifications of ionic liquid,metal nanoparticles and carbon nanotubes were reviewed. Finally, the plans for the dissertation were putforward.In the second chapter, a modified microcavicity electrode （MWNT-SH/AuNPs/MCE） wasfabricated based on self-assembling AuNPs on SWNT. The self-assembled surface has the merit ofsimplicity and can be further engineered by incorporating active elements．The results showed thatMWNT-SH/AuNPs/MCE exhibited linearly dependence on dopamine concentration in the range from2.6×10^-4to1.3×10-3mol·L^-1with a detection limit of8.5×10^-5mol·L^-1at a signal-to-noise ratio of3.In the third chapter，we proposed another dopamine sensor （SWNT&BMIMPF6/MCE） modified bySWNT&BMIMPF6composites. The addition of ionic liquids can effectively improve the conductivityand promote electron transfer between SWNT&BMIMPF6/MCE and dopamine.SWNT&BMIMPF6/MCE shows a dramatic electrocatalytic effect on the oxidation of dopamine. Theresults showed that SWNT&BMIMPF6/MCE exhibited linearly dependence on dopamine concentrationin the range from3.9×10^-5to2.9×10^-4mol·L^-1with a detection limit （3S/N） of3.56×10^-5mol·L^-1.In the fourth chapter， a novel amperometric hydrogen peroxide microcavity electrode（MWNTs-SH/AgNPs/MCE） was fabricated based on sulfhydryl-containing multi-walled carbon nanotube/silver nanoparticle heterojunctions. The results showed that MWNTs-SH/AgNPs/MCEexhibited linearly dependence on hydrogen peroxide. As the concentration of hydrogen peroxidebetween6.2×10^-5to7.9×10^-4mol·L^-1, It has better linear for the results and detection limit （3S/N）arrives at1.8×10^-5mol·L^-1. The MWNTs-SH/AgNPs/MCE has excellent selectivity, stability andrepeatability.In the fifth chapter, another H2O2sensor （MWNTs-SH/Pt-AgNPs/MCE） modified byPt-AgNPs/MWNT composites had been fabricated. The results showed that the best match of Pt-AgNPswas2:1and the reducer was NaBH4. The MWNTs-SH/Pt-AgNPs/MCE has excellent selectivity, andstability, and the detection limit （3S/N） arrives at3.0×10-6mol·L^-1.