Fabrication Of Polydopamine Based Nanocomposites And Their Applications In Catalysis

In this paper, based on the characteristics and advantages of the polydopamine materials, we expolyed the principles of synthesis of polydopamine based nanocomposites,the synthetic methods, structure and application in catalysis.Recently, due to the increasingly serious environmental pollution, exploring novel and efficient catalyst will make a significant role in the treatment of pollutants. We know that nanoparticles such as metal and iron oxide nanoparticles have a small scale,large specific surface area, thus studies have shown that they possess high catalytic activity in many reactions. However, they are prone to aggloment to a large block during use, which could restrict its applications to a large extent. Thus selecting a substrate to fix metal or iron oxide nanoparticles has been goals of many researchers.Polydopamine materials possess the unique property of adhesion, dispersion and chemical activity, thus they have been widely used in many areas and attract more and more attention In this paper, we synthesized Au-polydopamine and Fe₃O₄-polydopamine nanocomposites with a hollow embedded structure by using template-based self-assembly method. The morphology, structure, composition and catalytic properties of these microspheres have been thoroughly studied. The main results are as follows:（1） Firstly, the PS/Au-polydopamine composites were facilely fabricated by the polymerization of dopamine using polystyrene（PS） spheres as template in the gold sol solution under vigorous stirring. The the hollow Au-PDA composites were obtained after THF washing.（2） The PS/Fe₃O₄-polydopamine composites were successfully synthesized under vigorous mechanical agitation by the oxidation polymerization of dopamine using PS spheres as template in the Fe₃O₄ nanoparticles suspension. Finally the hollow Fe₃O₄-PDA composites were attained as soon as the core was removed in a THF solution.（3） The morphology, structure and properties of hollow Au-PDA composites aswell as hollow Fe₃O₄-PDA composites were characterized by scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, infrared spectroscopy（FT-IR）, ultraviolet-visible spectroscopy（UV-Vis）, thermal gravimetric analysis（TGA） and magnetic characterization, which explored the properties of the microspheres thoroughly.（4） Au-PDA hollow microspheres and Fe₃O₄-PDA hollow microspheres were employed as catalysts in the reduction of methylene blue and in the peroxidase mimetic catalysis experiments, respectively. The experimental process was explored by UV-Vis spectrum in different concentration of the catalysts, and the corresponding rate constant k was calculated. Moreover, we repeated the catalytic experiments for several times to examine their service life. As a comparison, the PDA/Au composites and PDA/Fe₃O₄ composites were also synthesized with surface-loaded structure.Results showed that the catalysts with hollow embedded structure show better catalytic activity and higher recyclability, which can be used as a good catalyst to solve environmental pollution.