Investigation Of Electrochemical Sensing Based On Four Kinds Of Nanocomposites

Due to the special chemical and physical properties of nanocomposites, they attracted more and more attentions in the research of electrochemical sensors. In this thesis, four kinds of different nanocomposites were synthesized and fabricated different electrochemical sensors. Electrochemical methods were used to study the electrochemical behavior of those sensors. Meanwhile, the new methods to the detection of hydrogen peroxide or nitrite were established. This study enriched the content of electrochemical sensors, and broadened the application of nanocomposites. Three chapters were included in this thesis, and the mian contents were showed as below:1. Ag/FeOOH nanocomposites were synthesized by hydrothermal and chemical reduction methods, and then a novel H₂O₂ sensor was fabricated through casting the noncomposites on the surface of PGE. The results indicated that the sensor can detecte H₂O₂ from 0.03 to 15.0 mmol L^-1, with a detection limit of 22.8 mmol L^-1 ?S/N=3?, and the response time was 3 s.2. Ag/MnO₂/GO nanocomposites were synthesized based on modified silver mirror reaction at the gas/liquid interface and an H₂O₂ electrochemical sensor was fabricated. The results indicated that the dispersity of Ag NPs was very well and the sensor showed an excellent performance for the H₂O₂ detection. The linear detection range of this sensor was from 0.003 to 7 mmol L^-1; the sensitivity was 105.40 ?A (mmol L^-1)^-1 cm^-2.3. Ni/Ag@C nanocomposites were synthesized by a chemical method, and an enzyme-free hydrogen peroxide sensor was fabricated based on the nanocomposites. The results showed this sensor could detect H₂O₂ in a linear range from 0.03 to 17 mmol L^-1, a sensitivity of 22.94 ?A (mmol L^-1)^-1 cm^-2 and a response time of 3 s.4. A novel non-enzymatic nitrite sensor was fabricated by the synthesized MnOOH/PANI nanocomposites. The electrochemical investigation of the sensor showed that it showed an excellent electrocatalytic property for NO₂^-. The sensor displayed a linear range from 3.0 ?mol L^-1 to 76.0 mmol L^-1, a sensitivity of 132.2 ?A (mmol L^-1)^-1 cm^-2 and a response time of 3s.