| In recent years, with the population growth, the environmental pollution is worsening, which threats seriously the health of human. The contamination of the environment has been an important concern throughout the world. The polyaniline (PANI) has been widely investigated because of its straight forward polymerization, chemical stability, relatively high conductivity, which has been applied in molecular electronic devices, fuel cells, nonlinear optics, sensors, etc. However, it is very necessary to study the property and develop its new applications. The composites containing PANI and inorganic nanoparticles are particularly useful due to their enhanced gas sensing properties and electrocatalytic activity, memory devices, and others, as compared to those of pure PANI. The synthesis of PANI/inorganic nanoparticles composites is one of important fields in nano-material research. In the dissertation, we have synthesized several nanocomposites, including Au/PANI, Ag@PANI, CuI/PANI and Fe3O4/PANI/Au. The composition, construction, application and properties of the products have also been investigated.The main results can be summarized as follows:1. The monodisperse, uniform dandelion-like Au/PANI composite nanospheres were synthesized by a simple one-step process without any additives or templates. The nanospheres are really composed of many short nanorods and the average diameter of whole nanospheres is about 180 nm. The morphology of Au/PANI composites could be controlled by adjusting the molar ratio of HAuCU to aniline. The prepared nanocomposite is developed as a wonderful sensor for the detection of Hg2+ ions, which is based upon the Raman intensity response of PANI to Hg2+ ions. Results from the morphology-dependent sensitivity investigations show that the dandelion-like nanospheres have an ultra sensitive response (as low as 10-11 M) compared with other morphologies. The nanosensor also exhibits good reproducibility and greater selectivity for Hg2+ ions than the other heavy metal ions. And the mechanism Was proposed. The proposed nanosensors can be applied for highly sensitive and selective chemical analysis in a variety of environmental detection.2. The Ag@PANI core-shell nanocomposites were successfully synthesized by one-step radiation of sunlight method using silver nitrate as the oxidant for aniline. The Ag@PANI core-shell nanocomposites were used as active surface enhanced Raman scattering (SERS) nanosensors for the detection of some heavy metal ions, such as Pb2+, Cu2+ Hg2+, Cd2+, and so on, which is based upon the Raman intensity response of PANI to different metal ions. It turns out that the nanosensors represent greater selectivity for Hg2+ ions detection than the other heavy metal ions. The nanosensors also exhibit a high sensitivity, and the detection limit of Hg2+ concentration is ca.1×10-12M in this system, due to the great sensitivity of SERS nanosensors. The reproducibility and stability of the sensor were measured in our system. The developed nanosensors could have potential applications in highly sensitive chemical, environmental and biological analysis, as well as medical detection.3. The CuI/PANI nanocomposites with sheet structure were successfully synthesized using CUSO4 as the oxidant for aniline in the presence of KI. The morphology of the composites can be controlled by adjusting the reaction conditions. Remarkably, the nanocomposites display excellent superhydrophobicity without further modification by low-free energy materials. The static contact angle for water on the surface of the resulting nanocomposites is over 160°. The special wettability is attributed to a hierarchical morphology of CuI/PANI nanocomposites with high roughnesses and the nature of the material itself. Moreover, for the first time, the photocatalytic property of as-synthesized CuI/PANI nanocomposites have been studied, which shows excellent photocatalytic activity for the degradation of rhodamine B under visible light irradiation. And the photocatalytic mechanism is proposed. The developed nanocomposites could have potential applications in superhydrophobic coatings, decontamination corrosion prevention, radiation proof, and so on. 4. We report a simple method to synthesize magnetically responsive Fe3O4/PANI/Au nanocomposites. The superparamagnetic Fe3O4 has been synthesized via facile solvothermal route. The positively charged aniline has been effectively assembled onto the negatively charged surface of the as-synthesized Fe3O4 nanospheres via electrostatic attraction. The aniline has been oxidized by HAuCl4, and Fe3O4/PAN/Au nanocomposites have been synthesized. Furthermore, Fe3O4/PANI/Au composites have been immobilized on the surface of a glassy carbon electrode (GCE) and applied to construct a sensor. The obtained Fe3O4/PANI/Au/GOD-modified GCEs show high catalytic activity for the oxidation of glucose.
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